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29 octobre 2026

Séminaire · invité par Benoit Cottereau

Integration of motion signals in amblyopia and pathways for new therapies

Alexandre Reynaud
McGill University

Jeudi 29 octobre 2026 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Amblyopia is a neurodevelopmental disorder that affects monocular and binocular visual functions. It affects how the visual signals from the two eyes are integrated over time which is critical for motion perception. In the first part of the talk, I will present how we used visual illusions to investigate how the amblyopic brain extrapolates, corrects and integrates motion signals. In the second part, I will present a novel digital therapy to train the amblyopic brain to combine the two eyes' images.
20 octobre 2026

Conférence CerCo

Neural Signatures of Motor Planning during Rapid Decision-Making

Leonardo Cano
Maitre de Conférences Invité

Mardi 20 octobre 2026 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Goal-directed actions can be prepared within a few hundred milliseconds, requiring the rapid integration of predictive, sensory, and motor information. Yet, the neural organization supporting rapid motor planning remains incompletely understood. Does the brain rely on a common architecture for preparing actions, or can different sensorimotor strategies support the same behavioral goal?
This talk presents evidence that motor planning under temporal uncertainty is not implemented through a single neural architecture. Using high-density EEG and EMG during goal-directed upper-limb tasks, we combined behavioral decomposition of reaction time, corticomuscular coherence, and graph-theoretical analyses of brain connectivity to investigate how motor planning is organized across effectors.
Two dissociable patterns emerged. Planning with the non-dominant hand was associated with direct brain?muscle communication, whereas planning with the dominant hand involved a distributed interhemispheric frontoparietal network whose connectivity scaled with planning duration. These findings suggest that similar motor goals can be supported by different neural organizations, challenging the idea of a single, fixed sensorimotor architecture.
This talk leaves an open question: whether decisions cause actions, or whether both emerge from the underlying sensorimotor processes. The sense?decide?act model has shaped how cognitive neuroscience designs experiments and interprets data. However, if decisions are nonphysical descriptions rather than physical causes, then studying movement in ecological, agent-driven environments?where participants actively sense and continuously update their actions?may not simply refine our models of decision-making. It may redefine what we think decision-making is.
6 octobre 2026

Conférence CerCo

Neuropsychology and imaging of the perception and memory of time

Thomas Hinault
NIMH, Université de Caen-Normandie

Mardi 6 octobre 2026 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Advancing age is associated with changes in the perception of time and in the temporal structuring of memory. However, the brain mechanisms underlying the reported changes in various aspects of temporal processing (order and rhythm processing, duration processing, felt passage of time, mental time travel) remain poorly known. We hypothesize that a disruption in synchronized brain communications could be associated with changes in temporal processing with age and that it may be predictive of longitudinal trajectories in older individuals. As part of the TIMES project, healthy young (20-35 years) and older (60-85 years) volunteers are currently performing a series of tasks assessing temporal processing while undergoing simultaneous electroencephalography and functional magnetic resonance imaging (EEG-fMRI) recordings. Preliminary results show distinct patterns of duration processing performance across groups, and differences in both brain regions and oscillatory activity engaged. A longitudinal follow-up will also aim at clarifying the association between these changes and individual cognitive trajectories. The application of multi-level modeling (EEG-fMRI) to the study of the dynamics of networks associated with temporal processing could provide new insights into the evolution of the neural bases of temporal processing with age and the cognitive heterogeneity in older individuals. In addition, the ongoing development of the CHRONOS battery, a short assessment of the four aspects of time, aims at specifying the distinct profiles of temporal abilities changes in healthy and pathological aging.
6 octobre 2026

Conférence CerCo

Neuropsychology and imaging of the perception and memory of time

Thomas Hinault
NIMH, Université de Caen-Normandie

Mardi 6 octobre 2026 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Advancing age is associated with changes in the perception of time and in the temporal structuring of memory. However, the brain mechanisms underlying the reported changes in various aspects of temporal processing (order and rhythm processing, duration processing, felt passage of time, mental time travel) remain poorly known. We hypothesize that a disruption in synchronized brain communications could be associated with changes in temporal processing with age and that it may be predictive of longitudinal trajectories in older individuals. As part of the TIMES project, healthy young (20-35 years) and older (60-85 years) volunteers are currently performing a series of tasks assessing temporal processing while undergoing simultaneous electroencephalography and functional magnetic resonance imaging (EEG-fMRI) recordings. Preliminary results show distinct patterns of duration processing performance across groups, and differences in both brain regions and oscillatory activity engaged. A longitudinal follow-up will also aim at clarifying the association between these changes and individual cognitive trajectories. The application of multi-level modeling (EEG-fMRI) to the study of the dynamics of networks associated with temporal processing could provide new insights into the evolution of the neural bases of temporal processing with age and the cognitive heterogeneity in older individuals. In addition, the ongoing development of the CHRONOS battery, a short assessment of the four aspects of time, aims at specifying the distinct profiles of temporal abilities changes in healthy and pathological aging.
5 octobre 2026

Conférence CerCo

Temporal interference stimulation of the striatum for motivation and learning

Pierre Vassiliadis
Max Planck Centre for Computational Psychiatry and Ageing Research; University College London

Lundi 5 octobre 2026 · 10h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Reward processing is central to adaptive behaviour. Retrospectively, reward outcomes are used to update action values and support learning; prospectively, expected rewards are weighed against anticipated costs to determine whether an action is worth pursuing. The striatum plays a key role in both processes, yet establishing its causal contribution in humans remains challenging. Conventional non-invasive brain stimulation techniques cannot selectively target deep striatal structures, while invasive approaches are restricted to specific clinical populations and anatomical targets.
Transcranial temporal interference stimulation (tTIS) has recently emerged as a promising approach for non-invasive neuromodulation of deep brain regions. In this talk, I will present initial human data supporting the safety, feasibility, and utility of the technique for addressing causal questions about deep-brain physiology. In particular, I will present two examples in which tTIS was used to investigate complementary roles of the human striatum in reward processing. In a first study, we found frequency-specific effects of striatal tTIS on reinforcement motor learning, associated with selective changes in striatal activity and frontostriatal connectivity. In a second study, we found behavioural, computational, and physiological evidence for distinct?and in some cases opposite?effects of different striatal tTIS protocols on effort-reward decision-making. Finally, I will discuss recent technological developments aimed at optimizing tTIS which may facilitate its wider scientific and clinical deployment. Together, these findings highlight tTIS as a promising tool for investigating the causal role of deep brain regions in human cognition.
15 septembre 2026

Conférence CerCo

From cortical columns to distributed networks:
how brain state controls sensory information flow

Pierre-marie Garderes
UC Berkeley

Mardi 15 septembre 2026 · 16h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Interaction with the environment requires the brain to transform local sensory signals into representations that can guide behavior, while flexibly adapting this transformation to behavioral state and task demands. Yet the circuit mechanisms controlling when local sensory activity is broadcast to other brain regions remain unclear. In this seminar, I will describe my work using the rodent tactile system as a model for investigating how computations across cortical columns and layers give rise to large-scale electrical dynamics during decision-making. Our initial studies showed that individual cortical columns in the primary sensory cortex contain reliable and causally relevant representations of sensory evidence, while ongoing multi-area recordings examine how this information becomes progressively shared across primary and secondary sensory cortices during behavior. I will then present a complementary approach combining high-density micro-electrocorticography (µECoG) with layer-specific optogenetics. These experiments reveal that high-gamma and low-frequency components of cortical surface-evoked potentials (CSEPs) arise preferentially from layer 5 and layer 2/3 circuits, respectively, providing biomarkers of distinct stages of columnar processing. Ongoing studies further suggest that arousal and task engagement selectively recruit layer 5 output and high-frequency activity in sensory cortex, promoting the broadcast of sensory information to downstream areas. These findings support a model in which behavioral state and task demands regulate sensory information flow by controlling layer 5 output from cortical columns. I will conclude by outlining a future research program investigating how cortical and thalamocortical networks dynamically route sensory information and organize continuous sensory input into discrete, behaviorally relevant events.
15 septembre 2026

Conférence CerCo

From cortical columns to distributed networks:
how brain state controls sensory information flow

Pierre-marie Garderes
UC Berkeley

Mardi 15 septembre 2026 · 16h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Interaction with the environment requires the brain to transform local sensory signals into representations that can guide behavior, while flexibly adapting this transformation to behavioral state and task demands. Yet the circuit mechanisms controlling when local sensory activity is broadcast to other brain regions remain unclear. In this seminar, I will describe my work using the rodent tactile system as a model for investigating how computations across cortical columns and layers give rise to large-scale electrical dynamics during decision-making. Our initial studies showed that individual cortical columns in the primary sensory cortex contain reliable and causally relevant representations of sensory evidence, while ongoing multi-area recordings examine how this information becomes progressively shared across primary and secondary sensory cortices during behavior. I will then present a complementary approach combining high-density micro-electrocorticography (µECoG) with layer-specific optogenetics. These experiments reveal that high-gamma and low-frequency components of cortical surface-evoked potentials (CSEPs) arise preferentially from layer 5 and layer 2/3 circuits, respectively, providing biomarkers of distinct stages of columnar processing. Ongoing studies further suggest that arousal and task engagement selectively recruit layer 5 output and high-frequency activity in sensory cortex, promoting the broadcast of sensory information to downstream areas. These findings support a model in which behavioral state and task demands regulate sensory information flow by controlling layer 5 output from cortical columns. I will conclude by outlining a future research program investigating how cortical and thalamocortical networks dynamically route sensory information and organize continuous sensory input into discrete, behaviorally relevant events.
7 septembre 2026

Conférence CerCo

Is My Red Your Red? A novel structural / mathematical approach to study Qualia (conscious experience)

Nao Tsuchiya
Monash University

Lundi 7 septembre 2026 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Recently, theories of consciousness have proliferated, partly because traditional empirical approaches focusing on neural correlates of consciousness (NCC) offer limited constraints. Unlike most traditional studies, which use binary paradigms (e.g., ?seen? vs. ?unseen?), a structural approach aims to characterize qualia and their physical substrates through relationships among qualia and between qualia and neural mechanisms. We present recent structural experiments and analyses that map properties of qualia (e.g., color, motion, sound, face, emotion) onto neural connectivity and activity. This framework may eventually yield a systematic catalogue of qualia?substrate relationships, akin to a ?periodic table of qualia,? providing a necessary step toward dissolving the hard problem of consciousness.
3 juillet 2026

Conférence CerCo

Animal fMRI for translational study

Tomokazu Tsurugizawa
AIST, Tsukuba, Japan

Vendredi 3 juillet 2026 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Animal fMRI for translational study
24 juin 2026

Soutenance de thèse

Soutenance de Thèse "Biomarqueurs IRM, Pupillaires et Cognitifs de la structure et la fonction du Locus Coeruleus dans le vieillissement humain"

Marie Fourteau
CerCo

Mercredi 24 juin 2026 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Résumé : Le vieillissement cognitif est un processus hétérogène, marqué par une vulnérabilité accrue de la mémoire épisodique et des fonctions
exécutives, tandis que d'autres fonctions sont relativement préservées. Ces différences s'accompagnent de modifications cérébrales variables et
de trajectoires individuelles distinctes, pouvant évoluer vers des formes pathologiques.
Dans ce contexte, le noyau Locus Coeruleus (LC), principale source de noradrénaline du cerveau, constitue une structure clé du vieillissement
cérébral. Il se caractérise par un réseau de projections particulièrement dense et diffus, qui l'implique dans de nombreux processus cognitifs de
haut niveau, et a été identifié comme le premier site d'accumulation de la protéine tau hyperphosphorylée, un marqueur cellulaire
caractéristique de la maladie d'Alzheimer. Deux biomarqueurs principaux permettent d'étudier le LC in vivo : le ratio de contraste en IRM sensible
à la neuromélanine, utilisé comme indicateurstructurel de son intégrité, et la réponse pupillaire, considérée comme un marqueur indirect de son
activité neuronale. L'activité électrophysiologique du LC repose sur une activité tonique, associée au niveau d'éveil général, et une activité
phasique caractérisée par des décharges transitoires en réponse à des stimuli saillants. La méthodologie d'imagerie du LC reste toutefois
hétérogène, reposant sur différentes séquences IRM, sensibles à la neuromélanine pondérées en T1 ou de transfert d'aimantation, ainsi que sur
des approches de segmentation manuelles, semi-automatiques ou automatiques pourl'estimation du ratio de contraste.
Ce travail de thèse vise à caractériser les biomarqueurs structurels et fonctionnels du LC et leurs corrélats cérébraux, cognitifs et
comportementaux, dans une cohorte de 101 sujets âgés asymptomatiques (72,2 ± 7,1 ans), à travers un protocole multimodal combinant IRM
sensible à la neuromélanine, IRM fonctionnel de repos, pupillométrie, évaluations cognitives standardisées et écologiques, et mesures des
habitudes de vie, en collaboration avec la cohorte INSPIRE, IHU HealthAge.
Les résultats montrent un déclin significatif du ratio de contraste du LC (LCCR) avec l'âge, associé à une réduction du volume du cortex
entorhinal, première cible corticale de la pathologie tau indépendamment de l'âge, ainsi qu'à une augmentation du volume de liquide
cérébrospinal et à une réduction de la connectivité fonctionnelle du LC vers l'hippocampe et vers les régions frontales en IRMf de repos. Une
association négative significative est observée entre les fluctuations spontanées du diamètre pupillaire basal et le LCCR, indépendamment de
l'âge, résultat inédit établissant pour la première fois un lien entre intégrité structurelle du LC et mesures pupillaires de repos. Le LCCR est
également associé positivement aux performances en mémoire de travail (tâche 2-back), domaine dépendant de la noradrénaline avant tout
déficit mnésique épisodique. Enfin, le LCCR est positivement associé au score de réserve cognitive (LEQ), la réserve cognitive modulant les
projections fonctionnelles du LC et les performances en mémoire de travail.
En conclusion, ce travail démontre que des signes précoces d'altération du système noradrénergique sont détectables chez des sujets âgés
asymptomatiques à l'aide d'outils non invasifs et complémentaires. Ces résultats ouvrent plusieurs perspectives, tant sur le plan de la recherche
fondamentale que dans le cadre des parcours de dépistage précoce en pratique clinique. L'analyse des données longitudinales permettra de
préciser la valeur prédictive de ces marqueurs et d'en évaluer la portée clinique.
24 juin 2026

Soutenance de thèse

Soutenance de Thèse "Biomarqueurs IRM, Pupillaires et Cognitifs de la structure et la fonction du Locus Coeruleus dans le vieillissement humain"

Marie Fourteau
CerCo

Mercredi 24 juin 2026 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
Résumé : Le vieillissement cognitif est un processus hétérogène, marqué par une vulnérabilité accrue de la mémoire épisodique et des fonctions
exécutives, tandis que d'autres fonctions sont relativement préservées. Ces différences s'accompagnent de modifications cérébrales variables et
de trajectoires individuelles distinctes, pouvant évoluer vers des formes pathologiques.
Dans ce contexte, le noyau Locus Coeruleus (LC), principale source de noradrénaline du cerveau, constitue une structure clé du vieillissement
cérébral. Il se caractérise par un réseau de projections particulièrement dense et diffus, qui l'implique dans de nombreux processus cognitifs de
haut niveau, et a été identifié comme le premier site d'accumulation de la protéine tau hyperphosphorylée, un marqueur cellulaire
caractéristique de la maladie d'Alzheimer. Deux biomarqueurs principaux permettent d'étudier le LC in vivo : le ratio de contraste en IRM sensible
à la neuromélanine, utilisé comme indicateurstructurel de son intégrité, et la réponse pupillaire, considérée comme un marqueur indirect de son
activité neuronale. L'activité électrophysiologique du LC repose sur une activité tonique, associée au niveau d'éveil général, et une activité
phasique caractérisée par des décharges transitoires en réponse à des stimuli saillants. La méthodologie d'imagerie du LC reste toutefois
hétérogène, reposant sur différentes séquences IRM, sensibles à la neuromélanine pondérées en T1 ou de transfert d'aimantation, ainsi que sur
des approches de segmentation manuelles, semi-automatiques ou automatiques pourl'estimation du ratio de contraste.
Ce travail de thèse vise à caractériser les biomarqueurs structurels et fonctionnels du LC et leurs corrélats cérébraux, cognitifs et
comportementaux, dans une cohorte de 101 sujets âgés asymptomatiques (72,2 ± 7,1 ans), à travers un protocole multimodal combinant IRM
sensible à la neuromélanine, IRM fonctionnel de repos, pupillométrie, évaluations cognitives standardisées et écologiques, et mesures des
habitudes de vie, en collaboration avec la cohorte INSPIRE, IHU HealthAge.
Les résultats montrent un déclin significatif du ratio de contraste du LC (LCCR) avec l'âge, associé à une réduction du volume du cortex
entorhinal, première cible corticale de la pathologie tau indépendamment de l'âge, ainsi qu'à une augmentation du volume de liquide
cérébrospinal et à une réduction de la connectivité fonctionnelle du LC vers l'hippocampe et vers les régions frontales en IRMf de repos. Une
association négative significative est observée entre les fluctuations spontanées du diamètre pupillaire basal et le LCCR, indépendamment de
l'âge, résultat inédit établissant pour la première fois un lien entre intégrité structurelle du LC et mesures pupillaires de repos. Le LCCR est
également associé positivement aux performances en mémoire de travail (tâche 2-back), domaine dépendant de la noradrénaline avant tout
déficit mnésique épisodique. Enfin, le LCCR est positivement associé au score de réserve cognitive (LEQ), la réserve cognitive modulant les
projections fonctionnelles du LC et les performances en mémoire de travail.
En conclusion, ce travail démontre que des signes précoces d'altération du système noradrénergique sont détectables chez des sujets âgés
asymptomatiques à l'aide d'outils non invasifs et complémentaires. Ces résultats ouvrent plusieurs perspectives, tant sur le plan de la recherche
fondamentale que dans le cadre des parcours de dépistage précoce en pratique clinique. L'analyse des données longitudinales permettra de
préciser la valeur prédictive de ces marqueurs et d'en évaluer la portée clinique.
24 juin 2026

Conférence CerCo

Neuroimaging the regulation of sleep and wakefulness and links with neurodegeneration

Gilles Vandewalle
GIGA-CRC Human Imaging, University of Liège

Mercredi 24 juin 2026 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Sleep and wakefulness are regulated through interactions between cortical and subcortical structures. This complex interplay has mostly been established in animal models, however, and translation to human beings is not straightforward. The presentation is intended to provide an overview of the recent work we conducted in our lab using MRI, PET and EEG, genetic and/or cognitive tests to gain novel insights on the regulation of sleep and wakefulness and its importance for brain health in humans.

Light exposure is a simple means to affect the subcortical circuits of sleep and wakefulness, and the first part of the presentation will focus on recent studies using 7 Tesla MRI to dissect in part the impact of light on subparts of the hypothalamus and amygdala and on the locus coeruleus.

The second part of the presentation will summarize studies interested in the emerging bidirectional detrimental links between sleep quality and neurodegeneration. We recently reported that sleep electrophysiology markers are associated with amyloid beta burden, as assessed though PET scans, and with the polygenic risk for developing neurodegenerative diseases, up to 3 to 5 decades prior to the typical onset of disease symptoms.

The final part of the presentation, we focus mainly, again, on the locus coeruleus as it may be key to the links between neurodegeneration and sleep. We recently reported that the activity and structure of the LC are associated with features of both rapid eye movement (REM) and non-REM sleep.
3 juin 2026

Séminaire · invité par Benoit Cottereau

Hardware-Aware Neural Architecture Search for Energy Efficient Edge AI

Bo Wang
Singapore University of Technology and Design (SUTD)

Mercredi 3 juin 2026 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Designing DNN models that run fast and use little energy on edge AI devices?like smartphones, wearables, or sensors?is a tough job. Engineers need to balance how well the model performs with how efficiently the hardware can run it. Traditional methods to find the best design choices take substantial time and computational costs. Hardware-Aware Neural Architecture Search (HW-NAS) provides an automated approach to design optimal neural network architectures together with hardware configurations for specific workloads. However, evaluating candidate networks can involve extensive training, which requires significant time and resources. While training-free NAS can reduce the evaluation costs, existing approaches still face major challenges such as poor performance, exponential growth of the joint design space, and non-trivial runtime. In this talk, we present three training-free NAS frameworks
that systematically address these challenges. We highlight how each framework improves performance, scalability, and evaluation efficiency, culminating in a practical and effective pathway for energy-efficient AI on edge platforms.
19 mai 2026

Séminaire · invité par Leila Reddy

A learning-evoked slow-oscillatory architecture paces population activity for offline reactivation across the human medial temporal lobe

Adrien Causse
Univ. Oxford

Mardi 19 mai 2026 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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24 avril 2026

Conférence CerCo

What does it take to wait?

Anne Giersch
Neurosciences & psychiatrie translationnelles, Université de Strasbourg

Vendredi 24 avril 2026 · 9h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
My work has been conducted in the framework of a clinical question: why do patients with schizophrenia report a disruption of the feeling of time continuity? This question led our team to question the way we predict events at different timescales. There is no doubt that we can prepare to process information in the near future. At least in some cases we are able to be precise at the level of milliseconds. However, does it mean that we constantly verify information at the level of milliseconds when we prepare for an event that will occur only in the next hundreds of milliseconds? A verification mechanism at the level of milliseconds might sub-tend our sense of continuity, but would be costly. We investigated how patients with schizophrenia prepare to process events at both timescales, and I will shortly summarize the data showing that they are impaired at both levels. To tackle the question of the interaction between the timescales, I will additionally show some data in neurotypicals relying on a new illusion. The results suggest that prediction at the level of milliseconds affects the prediction at a longer time scale and can be modulated, by means of a theta-burst stimulation on the cerebellum. I will tentatively propose a model of how prediction at different timescales may be integrated.
24 avril 2026

PhD defense

Jugements temporels multisensoriels audiovisuels :
des bases cérébrales aux performances comportementales

Solène Leblond

Vendredi 24 avril 2026 · 13h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Cette thèse porte sur les jugements temporels audiovisuels, depuis la perception de la
synchronie jusqu?à l?estimation du temps avant contact (TTC).
Dans un premier temps, elle s?intéresse à la fenêtre temporelle d?intégration (TBW),
définie comme l?intervalle temporel au sein duquel des stimuli auditifs et visuels sont
perçus comme synchrones et peuvent être intégrés en une seule représentation
perceptive.
Le premier objectif de cette thèse était d?identifier les bases cérébrales de la TBW
audiovisuelle à l?aide d?approches causales. Les participants ont réalisé une tâche de
jugement de simultanéité (SJ) lors de laquelle ils devaient déterminer si des stimuli
auditifs et visuels présentés avec différents délais étaient synchrones ou asynchrones,
tandis que deux méthodes complémentaires étaient utilisées : la stimulation magnétique
transcrânienne (TMS) et la stimulation électrique directe (DES) en chirurgie éveillée.
L?étude en TMS, grâce à une stimulation à différents délais post-stimulus, a montré une
implication précoce du gyrus temporal supérieur (STG) droit et du sillon intrapariétal
(IPS) gauche dans le traitement de la synchronie ainsi qu?une implication plus tardive du
STG bilatéral dans le jugement de l?asynchronie. L?étude en chirurgie éveillée a, quant à
elle, révélé l?implication causale d?un réseau fronto-pariétal droit, incluant notamment
l?IPS et de la SMA. Ensemble, ces résultats suggèrent une organisation hiérarchique du
traitement temporel audiovisuel avec des mécanismes perceptifs précoces médiés par le
STG et l?IPS gauche et des processus plus tardifs de haut niveau reposant sur le réseau
fronto-pariétal droit.
Le second objectif de cette thèse était d?étudier le rôle de cette intégration
multisensorielle dans des jugements temporels plus complexes du quotidien : le temps
avant contact (TTC). L?étude a comparé les performances d?estimation du TTC en
modalités visuelle, auditive et audiovisuelle à vitesse constante et accélérée. Les résultats
montrent que les indices auditifs entraînent une sous-estimation du TTC, pouvant
compenser une surestimation visuelle, notamment en condition accélérée, mais accentuer
l?erreur lorsque l?estimation visuelle est déjà sous-estimée comme pour les TTC longs.
Pris ensemble, ces résultats suggèrent que l?utilisation des indices auditifs est modulée
par le contexte dynamique et les performances perceptives de base, possiblement via un
contrôle top-down exercé par le réseau fronto-pariétal.
24 avril 2026

Conférence CerCo

A taxonomy for visual time perception

Pascal Mamassian
Laboratoire des Systèmes Perceptifs, École Normale Supérieure (ENS), Paris

Vendredi 24 avril 2026 · 10h15 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
There are a large variety of visual time phenomena, but researchers have mostly studied them in isolation. The ambition of this presentation is to offer a principled way to categorize these phenomena into twelve categories. The main distinction is between two super-ordinate concepts, the perception of succession of events from that of instantaneity. For each of these categories, I'll present briefly the main methodologies that have been used to investigate these phenomena.
16 avril 2026

Séminaire · invité par Antoine Grimaldi

Working Memory in Recurrent Spiking Neural Networks With Heterogeneous Synaptic Delays

Laurent Perrinet
Insitut de Neurosciences de la Timone, Marseille

Jeudi 16 avril 2026 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Working memory ? the capacity to retain and retrieve precise temporal sequences of neural activity ? remains a major challenge for spiking neural networks (SNNs). We introduce a recurrent SNN in which every synapse is endowed with a rich set of heterogeneous transmission delays. By representing the full collection of delays as a three?dimensional weight tensor and training the network end?to?end with surrogate?gradient back?propagation through time, the model learns to store and recall arbitrary spike patterns. Each target pattern is decomposed into a chain of overlapping ?spiking motifs?: short, contiguous windows that uniquely predict the spikes at the next time step. On a synthetic benchmark comprising eight distinct temporal patterns encoded in a network of 512 neurons over 1?000 time steps, recall of the stored sequences emerges first within the initial clamped window and then propagates forward through the network dynamics, the final trained system achieves a mean F1 score of 0.97. These findings demonstrate that heterogeneous synaptic delays constitute an efficient substrate for implementing working memory in SNNs, paving the way for low?power, edge?compatible neuromorphic applications.
15 avril 2026

Conférence CerCo

Génération Myopie :
Enrayer l?épidémie mondiale grâce à l?innovation

Guillaume Giraudet
EssilorLuxottica

Mercredi 15 avril 2026 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
La myopie infantile, trouble de la réfraction entraînant une vision floue de loin, connaît une progression mondiale rapide : elle touche déjà plus d?un tiers des jeunes et pourrait concerner 50% de la population en 2050, avec des taux particulièrement élevés en Asie. Pourquoi la prévalence de la myopie augmente-t-elle aussi rapidement, partout dans le monde ? Même si les connaissances restent incomplètes, les chercheurs s?accordent sur le rôle prépondérant de l?environnement dans la survenue de ce défaut visuel. La réduction du temps passé en extérieur, l?usage intensif des écrans et la prédominance des activités en vision rapprochée seraient des facteurs impliqués dans le développement de la myopie infantile. Au-delà de la gêne visuelle qu?elle engendre, une myopie précoce accroît le risque de complications graves à l?âge adulte, comme le décollement de rétine, le glaucome, la cataracte et la maculopathie myopique, pouvant mener à une perte visuelle irréversible. Heureusement, des solutions existent pour freiner cette épidémie. Parmi les produits actuellement présents sur les marchés, le verre de lunettes Essilor® Stellest® constitue une option thérapeutique de premier choix. Il permet de ralentir la progression de la myopie de 67% en moyenne, sur 2 ans, sans aucun effet secondaire. Ce séminaire, animé par Guillaume Giraudet, présentera la méthodologie adoptée par les équipes de recherche d?EssilorLuxottica, leader mondial des solutions ophtalmiques, pour concevoir ce verre innovant Essilor® Stellest®. Il détaillera les principes optiques sous-jacents et les essais cliniques ayant permis de démontrer son efficacité dans le contrôle de la progression myopique juvénile.
15 avril 2026

Conférence CerCo

Génération Myopie :
Enrayer l?épidémie mondiale grâce à l?innovation

Guillaume Giraudet
EssilorLuxottica

Mercredi 15 avril 2026 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
La myopie infantile, trouble de la réfraction entraînant une vision floue de loin, connaît une progression mondiale rapide : elle touche déjà plus d?un tiers des jeunes et pourrait concerner 50% de la population en 2050, avec des taux particulièrement élevés en Asie. Pourquoi la prévalence de la myopie
augmente-t-elle aussi rapidement, partout dans le monde ? Même si les connaissances restent incomplètes, les chercheurs s?accordent sur le rôle prépondérant de l?environnement dans la survenue de ce défaut visuel. La réduction du temps passé en extérieur, l?usage intensif des écrans et la prédominance des activités en vision rapprochée seraient des facteurs impliqués dans le développement de la myopie infantile. Au-delà de la gêne visuelle qu?elle engendre, une myopie précoce accroît le risque de complications graves à l?âge adulte, comme le décollement de rétine, le glaucome, la cataracte et la maculopathie myopique, pouvant mener à une perte visuelle irréversible. Heureusement, des solutions existent pour freiner cette épidémie. Parmi les produits actuellement présents sur les marchés, le verre de lunettes Essilor® Stellest® constitue une option thérapeutique de premier choix. Il permet de ralentir la progression de la myopie de 67% en moyenne, sur 2 ans, sans aucun effet secondaire. Ce séminaire, animé par Guillaume Giraudet, présentera la méthodologie adoptée par les équipes de recherche d?EssilorLuxottica, leader mondial des solutions ophtalmiques, pour concevoir ce verre innovant Essilor® Stellest®. Il détaillera les principes optiques sous-jacents et les essais cliniques ayant permis de démontrer son efficacité dans le contrôle de la progression myopique juvénile.
9 avril 2026

Conférence CerCo

Multimodal dynamics of brain-body neuroscience

Daniel Kluger
Institute for Biomagnetism and Biosignal Analysis, Münster

Jeudi 9 avril 2026 · 11h Salle de conférence (Pavillon Baudot), Visioconférence

Affiche
19 mars 2026

Séminaire · invité par Antoine Grimaldi

Neuropharmacology of psychedelic substances DMT and 5-MeO-DMT:
from mechanisms to modulating factors

Romain Hacquet
CRCA

Jeudi 19 mars 2026 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Psychedelic substances, such as LSD or psilocybin, are gaining renewed interest for their potential therapeutic applications. Among them, DMT and 5-MeO-DMT produce brief subjective effects, while potentially inducing lasting antidepressant effects. However, their mechanisms of action remain incompletely understood, and individual and contextual factors (?set and setting?) surrounding administration appear to play a key role. To explore these questions, we conducted translational research from mice to humans.


In mice, these compounds showed rapid antidepressant-like effects associated with neuroplasticity mechanisms, likely involving the serotonergic system, particularly the 5-HT1A and 5-HT2A receptors. In addition, modulation of the administration context (setting) enhanced the antidepressant effects and the underlying plasticity, while limiting anxiety-like effects.


In humans, a systematic review of the literature characterized the adverse effect profile of DMT and 5-MeO-DMT, highlighting the role of setting and certain vulnerability factors in the occurrence of adverse events. In addition, the French translation and validation of the psychometric scale 5D-ASC in 800 participants allowed the assessment of the quality and intensity of psychedelic experiences. This survey also showed that experience intensity is associated with estimated dose, intention, and age. Finally, exploratory approaches conducted in our group suggest stable epigenetic modifications of genes related to neuroplasticity, angiogenesis, and immunity, while an ongoing study at CerCo is examining subacute brain activity after psychedelic use and its relationship with psychological state.


Overall, these findings suggest potential lasting therapeutic benefits and an acceptable risk profile in clinical settings, while emphasizing the heterogeneity of effects depending on individual and contextual factors. This variability represents a major challenge for the development and clinical integration of these compounds as potential therapeutic agents.
9 mars 2026

Conférence CerCo

Traveling waves of neural activity shape computation across sensory maps

Lyle Muller
Department of Mathematics, Western University

Lundi 9 mars 2026 · 15h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
New technologies now enable simultaneous measurement of neural activity across single cortcal
regions with high spatial and temporal resolution. Using computational techniques we developed
for these data, we found that visual stimuli evoke waves traveling outward from the
point of input in primary visual cortex (Muller et al., Nature Communications, 2014). This is a
spatiotemporally structured pattern of neural activation, analogous to ?the wave? in a stadium,
but where only a subset of fans stand at each point. During controlled visual detection tasks,
these neural traveling waves (nTWs) dynamically modulate both neural excitability and visual
perception (Davis*, Muller*, et al., Nature, 2020). nTWs thus actively affect visual processing ?
but what could be their computational role? In recent work, we developed a recurrent neural
network (RNN) architecture where brief input sequences trigger wave patterns that forecast upcoming
inputs (Benigno et al., Nature Communications, 2023). Analyzing this model mathematcally
demonstrates nTWs can enable predictive spatiotemporal computation by embedding continuous
structures that unfold across maps of sensory space. These findings lead to a general
framework for computation with spatiotemporal dynamics in topographically organized RNNs
(Budzinski*, Busch* et al., Communications Physics, 2024; Liboni*, Budzinski*, Busch* et al.,
PNAS, 2025).
5 mars 2026

Séminaire · invité par Antoine Grimaldi

Peer presence modulates cortico-subcortical networks of inhibitory control in cocaine and alcohol use

Damiano Terenzi
Université de Nîmes

Jeudi 5 mars 2026 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Addictive behaviors are strongly shaped by interpersonal context, yet the neurobiological mechanisms through which peer presence influences inhibitory control remain insufficiently understood. Animal studies highlight a key role of the Subthalamic Nucleus (STN) in mediating peer-related modulation of drug intake, reducing cocaine consumption while increasing alcohol use. Translating these findings to humans, we investigated how peer presence and substance-related cues interact to influence inhibitory control and its neural substrates in cocaine and alcohol use.

Using functional magnetic resonance imaging (fMRI) and a novel Social Stop-Signal Task, we examined individuals with cocaine use disorder (CUD), heavy drinkers (HD), and matched control groups while participants performed inhibitory control trials either alone or in the presence of a peer, and while exposed to drug- or alcohol-related versus neutral cues.

In cocaine use disorder, cocaine cues paradoxically enhanced stopping performance compared to neutral cues. Critically, peer presence reversed cue-related neural effects within the right STN, right inferior frontal gyrus, and bilateral orbitofrontal cortex, highlighting a strong modulation of inhibitory control circuits by interpersonal context. In contrast, heavy drinkers showed improved inhibitory control when alone, but this advantage diminished in the presence of a peer. Greater alcohol use severity was associated with poorer inhibition in response to alcohol cues. Peer presence strengthened functional connectivity between the STN and frontal?insular control regions specifically during alcohol cue exposure in heavy drinkers.

Together, these findings demonstrate that peer presence dynamically reshapes inhibitory control networks in substance use, with substance-specific patterns for cocaine and alcohol. The results underscore the importance of incorporating interpersonal context into addiction neuroscience and further support the STN as a promising neuromodulatory target for intervention.
3 mars 2026

Séminaire · invité par Benoit Cottereau

Hardware-Aware Neural Architecture Search for Energy Efficient Edge AI

Bo Wang
Singapore University of Technology and Design (SUTD)

Mardi 3 mars 2026 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Designing DNN models that run fast and use little energy on edge AI devices-like smartphones, wearables, or sensors?is a tough job. Engineers need to balance how well the model performs with how efficiently the hardware can run it. Traditional methods to find the best design choices take substantial time and computational costs. Hardware-Aware Neural Architecture Search (HW-NAS) provides an automated approach to design optimal neural network architectures together with hardware configurations for specific workloads. However, evaluating candidate networks can involve extensive training, which requires significant time and resources. While training-free NAS can reduce the evaluation costs, existing approaches still face major challenges such as poor performance, exponential growth of the joint design space, and non-trivial runtime. In this talk, we present three training-free NAS frameworks
that systematically address these challenges. We highlight how each framework improves performance, scalability, and evaluation efficiency, culminating in a practical and effective pathway for energy-efficient AI on edge platforms.
24 février 2026

Soutenance d'HDR · invité par Isabelle Berry

soutenance d'HDR

Safouane Hamdi
CERPOP équipe BIOETHICS (futur associé à NemoCog)

Mardi 24 février 2026 · 13h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
En tant que futur associé à NemoCog pour voir comment les facteurs hormonaux modulent l'activité cognitive, je vous invite à ma soutenance d'HDR

RESUME

L?infertilité masculine (IM) touche entre 10 et 16 % de la population masculine générale et est responsable d?environ 50 % de toutes les infertilités de couple. Bien que les premières recommandations concernant l?exploration et la prise en charge de l?IM aient été publiées par l?OMS en 2000, les experts constatent que les progrès en andrologie sont insuffisants par rapport à ceux réalisés dans d'autres champs de la santé. Les principales raisons en sont le déficit d'exploration encore important des hommes infertiles, l'insuffisance de la recherche et la faible sensibilisation de la société. Le manuscrit et la soutenance présenteront dix années de recherche en andrologie, et plus particulièrement sur le potentiel des biomarqueurs dans des situations physiopathologiques pour lesquelles des lacunes de connaissances ont été identifiées. Il s'agit notamment de l'exposition à la chaleur, des anomalies congénitales du système urinaire et génital (cryptorchidie, agénésie des voies séminales) ou des troubles fonctionnels acquis. Ces travaux ont permis d'identifier comment les biomarqueurs, et plus particulièrement leur combinaison, pouvaient éclairer la physiopathologie, stratifier les patients en sous-groupes distincts, aider au diagnostic étiologique ou à la prédiction des risques chez le partenaire masculin des couples infertiles. Ils ont également contribué à une synthèse sur le développement embryologique du tractus génital mâle et sur l?ontogenèse hormonale gonadotrope. En conclusion de ce travail essentiellement phénotypique, il apparaît que la combinaison des outils numériques avec les explorations génétiques et épigénétiques sera source de progrès majeurs en andrologie, au bénéfice des couples infertiles mais aussi pour la santé de l?homme en général.
Mots-Clés :
Santé reproductive, andrologie, infertilité
19 février 2026

Séminaire · invité par Antoine Grimaldi

Mastering learning about relations:
A honeybee perspective

Aurore Avarguès-weber
CRCA

Jeudi 19 février 2026 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Categories and concepts are instrumental in shaping our analytical mind. While humans excel in manipulating abstract relations in link with language development, this ability is built upon biological roots shared with non-human primates. Surprisingly, accumulated evidence suggest that an insect brain possesses similar relational concept learning capacities. I will present studies showing that honeybees indeed use spatial configurations to classify and recognise objects, extract relational rules and statistics from visual inputs or possess a sense of number. Such intriguing cases of evolutionary convergences raise fundamental questions upon the evolution of intelligence and its link with brain size.
8 janvier 2026

Conférence CerCo

From Exploration to Structured Navigation:
Learning Dynamics of Freely Moving Marmosets during Foraging

Nada El Mahmoudi
Peyrache lab, The Neuro (Montreal Neurological Institute), McGill University, Canada

Jeudi 8 janvier 2026 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Spatial memory plays a crucial role in guiding navigation and optimizing foraging efficiency. While extensive research has explored navigation strategies in rodents, how these strategies emerge and evolve in freely moving non-human primates remains poorly understood. Here, we conducted a longitudinal study to investigate the dynamics of spatial learning and navigation strategies in freely moving common marmosets (Callithrix jacchus) performing a foraging task in a semi-naturalistic environment. Marmosets were trained to collect rewards from eight spatially distributed dispensers. Using behavioral and computational analyses, we examined how their navigation strategies evolved over time. Our results reveal a progressive improvement in performance, accompanied by an increasing structuring of movement patterns. Initially, marmosets exhibited exploratory behaviors, with high transition variability between dispensers. As training progressed, their navigation became more structured, with the emergence of recurrent transition patterns and a shift towards route-based navigation. However, despite this increasing regularity, their navigation retained a degree of flexibility, allowing them to dynamically adapt their routes rather than following a fixed sequence. These findings demonstrate that marmosets develop structured yet flexible navigation strategies through experience, balancing efficiency and adaptability. Our study provides novel insights into spatial memory development in primates and highlights the value of semi-naturalistic paradigms for studying navigation strategies and spatial learning in freely moving animals.
2025 24
18 décembre 2025

Soutenance de thèse

Restauration des fonctions auditives et cognitives chez les enfants sourds implantés cochléaires

Yann Lemaire
CerCo

Jeudi 18 décembre 2025 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
18 décembre 2025

Séminaire · invité par Gregor Thut

Nouvelle technique au CerCo :
Stimulation cérébrale profonde non-invasive par ultrasons

Thomas Tiennot (sonomind) Et Gregor Thut

Jeudi 18 décembre 2025 · 11-12 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
We will present a new technique that will be available at CerCo/P Baudot: low-intensity transcranial focus ultrasound (li-tFUS) which has a subcortical reach and hence allows for non-invasive deep brain stimulation. We will present an introduction to the technique (Thomas) and place it in the local context (projects and opportunities) (Gregor). All welcome
16 décembre 2025

Conférence CerCo

The voice as a window into the brain

Pauline Larrouy-maestri
Max Planck Institute for Empirical Aesthetics. Frankfurt am Main. Germany

Mardi 16 décembre 2025 · 15h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The voice is a multifaceted tool that is central to human experience. To identify a speaker, understand their message, or enjoy a singing performance, listeners map acoustic properties and meaning(s). This talk investigates how the strength and nature of these acoustics-meaning mappings might reveal underlying cognitive and neural architecture.

Pauline Larrouy-Maestri is a senior researcher at the Max Planck Institute for Empirical Aesthetics in Frankfurt, Germany. With a background in pedagogy, psychology, piano performance, speech-language pathology, and a PhD in cognitive sciences, Pauline investigates how we categorize acoustic information and make sense of sounds, with a particular focus on vocalizations.
11 décembre 2025

Soutenance de thèse

Multimodal Grounding in Reinforcement Learning for Robotic Navigation and Manipulation Using a Global Workspace Architecture

Leopold Maytié
CerCo

Jeudi 11 décembre 2025 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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9 décembre 2025

Conférence CerCo

Biologically Inspired Neural Networks as Mechanistic Models of Cognition and Its Disorders

Anthony Strock

Mardi 9 décembre 2025 · 16h Salle de conférence (Pavillon Baudot), Visioconférence

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Résumé
How can neural network models help us understand both healthy cognition and its disruption in brain disorders? I will present two modeling studies that approach this question from different angles. First, I will show how recurrent neural networks with short-term synaptic depression can reproduce key attentional electrophysiological responses (MMN and P300) in oddball paradigms, suggesting a unified mechanism for automatic and controlled attention and offering insights into how synaptic changes can alter these responses. Second, I will describe an investigation of the neurophysiological mechanisms underlying learning disabilities based on biologically inspired neural networks tailored to individual children?s behavioral performance. Models fitted to children with learning disabilities not only reproduce their lower accuracy and slower learning but also display the same neural representational deficits and point to neuronal hyperexcitability as a potential causal driver of these impairments.
4 décembre 2025

Conférence CerCo

Vers une compréhension intégrée du système vestibulaire efférent :
du modèle rongeur au primate non humain

Guillaume Rastoldo
VESTIMED Team, Centre de Recherche en Psychologie et Neurosciences (CRPN) CNRS - Aix-Marseille Université

Jeudi 4 décembre 2025 · 16h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Guillaume will present us his project of application for a CR CNRS position this year (section 28), in SV3M team.
1 décembre 2025

Soutenance de thèse

Deep learning approaches to model single-unit neural responses in the auditory system

Ulysse Rançon
CerCo

Lundi 1 décembre 2025 · 9h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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1 décembre 2025

Conférence CerCo

How does the brain construct auditory space?

Jennifer Bisley
University College London, The Ear Institute

Lundi 1 décembre 2025 · 15h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The position of a sound source must be computed using sound localisation cues, that arise principally from the separation of the two ears on the head. These cues are extracted by dedicated brainstem nuclei, yet auditory cortex is required for accurate sound localisation, raising the question of what the role of auditory cortex is. I will review recent electrophysiology work from our lab that suggests that one role of auditory cortex may be to map sounds into listener independent (?world-centered?) reference frames, and present some unpublished work in which we attempt to take a more naturalistic approach to studying sound localisation.
1 décembre 2025

Conférence CerCo

Temporal integration in the auditory cortex across cortical areas and vigilance states

Yves Boubenec
ENS / Institut de l'Audition

Lundi 1 décembre 2025 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
How does auditory cortex integrate sound over time to support perception of natural, temporally structured stimuli? Natural sounds span tens to hundreds of milliseconds, yet it remains unclear whether how auditory cortex neurons integrate across multiple scales and flexibly adapt their integration depending on context or internal state.
We recorded neural activity with microelectrode arrays across primary and non-primary auditory fields in awake ferrets, and quantified each site's temporal integration window using a context-invariance approach. Integration windows were largely fixed, ranged from ~15 to >150 ms, and increased systematically along the cortical hierarchy and across layers. Their duration did not change with stimulus information rate, indicating multiscale integration arises from a division of labor across neuronal populations.
To examine how internal state shapes these timescales, we monitored physiological signals and transitions across wakefulness, natural sleep, and sedation. While spontaneous fluctuations in arousal modulated response gain, they did not alter integration windows. In contrast, sedation reliably lengthened integration timescales; ongoing work tests whether similar changes emerge during sleep.
These results suggest that temporal integration is a stable and hierarchical property of auditory cortex, robust across natural wake?sleep states and sensitive only to major state transitions.
27 novembre 2025

Conférence CerCo

Bio-inspired self-supervised learning of visual representations

Arthur Aubret
candidat concours CR NeuroAI

Jeudi 27 novembre 2025 · 10h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Despite recent advances in self-supervised visual deep learning, humans develop more robust representations with much fewer data. A key difference is that humans learn by moving, looking and manipulating objects, rather than from a static image datasets. In this talk, I will show how such embodied learning mechanisms can shape visual representation learning. I will first provide computational evidence that the temporal structure of humans' experience favors the emergence of semantic object representations. Then, I will introduce a self-supervised visual learning model that integrates eye saccades and object manipulation. The model reveals that egocentric actions can broadly boost visual learning and challenges common assumptions about children's cognitive strategies in classical object recognition tasks. Together, these findings suggest that the embodied nature of human visual experience may be key to reproducing the exceptional visual development observed in humans.
19 novembre 2025

Conférence CerCo

Cortical Plasticity Following Visual Field Loss:
From Animal Models to Human Rehabilitation

Kalina Burnat, Phd
Laboratory of Brain Imaging, Nencki Institute, Warsaw, Poland

Mercredi 19 novembre 2025 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Visual perception relies on both central and peripheral inputs, with bright slow-motion stimuli primarily processed centrally and fast dark-motion stimuli peripherally. To investigate these mechanisms, we developed a motion-based acuity test that simultaneously evaluates shape and motion perception using bright or dark motion patterns.
In a cat model of age-related macular degeneration (AMD), central retinal lesions led to reduced white matter integrity in visual and associative regions, including V5, dLGN, hippocampus, caudate nucleus, and optic tract. Rapid visual training based on motion-acuity task promoted functional recovery and structural reorganization, highlighting the potential of peripheral stimulation to support neural plasticity.
Extending these findings to humans, we tested 31 retinitis pigmentosa (RP) patients with chronic peripheral vision loss and healthy controls with transiently restricted peripheral vision. RP patients exhibited decreased activation in primary peripheral visual areas (V1?V3), MT+/V5, and salience networks. Controls with temporary peripheral restriction showed compensatory cortical engagement, illustrating the flexible adaptation of perceptual strategies in response to reduced visual input. We also tested Stargardt patients with juvenile congenital AMD.
Together, these results underscore the remarkable capacity for cortical plasticity following both transient and chronic visual field loss, positioning motion-based acuity assessment as a promising tool for diagnostic and rehabilitative strategies in ophthalmology.
Selected References:
· Ninghetto M, et al. J Vis Exp. 2024;204.
· Kozak A, et al. Behav Brain Funct. 2024;20(1):13.
· Ninghetto M, et al. Sci Rep. 2024;14(1):26264.
13 novembre 2025

Séminaire · invité par Jean-baptiste Durand, Alexandra Séverac Et Sarah Marchand

Mini-symposium Jury de thèse de Sarah Marchand-talk2 // Cross-modal association and Semantic Coding in the Macaque Cortex:
from Context to Concepts

Suliann Ben Hamed
Institut des Sciences Cognitives Marc Jeannerod, Lyon

Jeudi 13 novembre 2025 · 10h45 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Social communication requires the association of auditory and visual information into coherent, meaning-based representations. Using fMRI in awake macaques, we identified a fronto-temporal network in which species-specific vocalizations are enhanced or suppressed depending on their congruence with the visual social context, as defined by facial expressions or social scenes. This cortical network is tightly coupled with a subcortical ensemble including the amygdala, pulvinar, and claustrum, which modulate context-dependent gating and the salience of social information, suggesting that semantic integration relies on dynamic interactions between associative cortical areas and deep structures orchestrating emotional and attentional relevance. In the superior temporal sulcus (STS) and the prefrontal cortex (area 45a), neuronal activity patterns revealed amodal encoding of social context rather than sensory features, with mixed-selectivity neurons sustaining context-specific representations across trials and dynamically biasing sensory processing?indicating a top-down semantic control over audio-visual integration. Together, these results reveal a hierarchical social-semantic network in which the prefrontal cortex drives sensory processing in temporal and lateral sulcus cortical areas as well as in a specialized subcortical social network. This integrative architecture appears conserved across species and suggests that the neural foundations of conceptual coding and proto-syntactic organization emerged from the progressive coupling of perceptual, emotional, and executive systems in the primate brain.
13 novembre 2025

Conférence CerCo

Mini-symposium Jury de thèse de Sarah Marchand-talk1 // The Perception?Action Loop:
a Framework for Anticipating movement Intentions

Annalisa Bosco
Département des Sciences Biomédicales et Neuromotrices, Université de Bologna

Jeudi 13 novembre 2025 · 10h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Perception and action are deeply interwoven processes that shape how humans and animals interact with their environment. Increasing evidence highlights that action planning can influence perceptual processing, suggesting a continuous bidirectional exchange between motor intentions and sensory input. Differences in perception can emerge even before movement begins, and actions such as reaching or grasping can subsequently alter the way objects are experienced. At the neural level, these dynamics are thought to rely on perception?action interfaces supported by the parieto-frontal network. Understanding how action modulates perception not only provides insights into fundamental brain mechanisms but also offers promising avenues for designing AI systems that can better anticipate and adapt to action intentions.
12 novembre 2025

Soutenance de thèse · invité par Sarah Marchand

Investing space:
visual and vestibular stimulations to study the cortical integration of self-motion in human and non-human primates

Sarah Marchand
CNRS

Mercredi 12 novembre 2025 · 16h Auditorium du CBI, Université Paul Sabatier

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Résumé
The aim of this thesis work is to identify and characterize the cortical networks involved in visuo-vestibular integration in human and non-human primates, using functional magnetic resonance imaging (fMRI), in order to gain a better understanding of the neural mechanisms involved in the multisensory processing of spatial information. Inscribed in the field of cognitive neuroscience and neuroimaging, this project adopts a comparative approach to explore the integration processes essential to spatial orientation, balance and perception of self-motion. It also seeks to validate the rhesus macaque as a relevant model in this field, and to fill gaps on the neural substrates of visuo-vestibular integration, complementing behavioral, postural, oculometric and electrophysiological studies.
We conducted three studies. The first one, in humans, explored the directional and congruence effects between galvanic vestibular stimulation (GVS) and forward/backward optic flow, targeting five cortical areas sensitive to visual self-motion (V6, VIP, MT+, PIC, CSv). The second one compared vestibular activations in response to lateral GVS and visual (global optic flow) stimulation in macaque monkeys, to identify areas of overlap between the two modalities. The third study analyzed directional preferences to optic flow (forward/backward/left/right) in both species. Despite several technical challenges, such as adapting the GVS material to MRI and the complex training of macaques to the fixation task in the scanner, the data obtained enabled us to meet our objectives. Area V6, in humans, was characterized by a dual specialization: on the one hand, its sensitivity to visuo-vestibular congruence, and on the other, its preference for forward movement. In the macaque, notable functional overlaps were observed between vestibular and visual activations, with an organization similar to that of humans, although certain regions (e.g., VIP) showed differences in directional specialization. The final protocol confirmed the directional preference of V6 in macaques for forward flow, even in purely visual stimulation.
This project demonstrates the feasibility of a comparative fMRI approach to visuo-vestibular networks. It contributes to the characterization of the cortical multisensory integration network, to a better understanding of the specialization of certain regions in the perception of self-motion, and to the validation of the rhesus macaque as a relevant model due to functional homology with humans. This work paves the way for electrophysiological studies in non-human primates, to explore in greater detail the dynamics of the regions identified. It also lays the foundations for new experimental protocols integrating oculometric measurements to address the perceptual dimension of multisensory integration. In humans, this research could be extended to the study of the impact of gravity or aging, opening up clinical prospects for the diagnosis and rehabilitation of vestibular disorders.
12 novembre 2025

PhD defense · invité par Sarah Marchand

Investing space:
visual and vestibular stimulations to study the cortical integration of self-motion in human and non-human primates

Sarah Marchand
CNRS

Mercredi 12 novembre 2025 · 16h Auditorium du CBI, Université Paul Sabatier

Affiche
Résumé
The aim of this thesis work is to identify and characterize the cortical networks involved in visuo-vestibular integration in human and non-human primates, using functional magnetic resonance imaging (fMRI), in order to gain a better understanding of the neural mechanisms involved in the multisensory processing of spatial information. Inscribed in the field of cognitive neuroscience and neuroimaging, this project adopts a comparative approach to explore the integration processes essential to spatial orientation, balance and perception of self-motion. It also seeks to validate the rhesus macaque as a relevant model in this field, and to fill gaps on the neural substrates of visuo-vestibular integration, complementing behavioral, postural, oculometric and electrophysiological studies.
We conducted three studies. The first one, in humans, explored the directional and congruence effects between galvanic vestibular stimulation (GVS) and forward/backward optic flow, targeting five cortical areas sensitive to visual self-motion (V6, VIP, MT+, PIC, CSv). The second one compared vestibular activations in response to lateral GVS and visual (global optic flow) stimulation in macaque monkeys, to identify areas of overlap between the two modalities. The third study analyzed directional preferences to optic flow (forward/backward/left/right) in both species. Despite several technical challenges, such as adapting the GVS material to MRI and the complex training of macaques to the fixation task in the scanner, the data obtained enabled us to meet our objectives. Area V6, in humans, was characterized by a dual specialization: on the one hand, its sensitivity to visuo-vestibular congruence, and on the other, its preference for forward movement. In the macaque, notable functional overlaps were observed between vestibular and visual activations, with an organization similar to that of humans, although certain regions (e.g., VIP) showed differences in directional specialization. The final protocol confirmed the directional preference of V6 in macaques for forward flow, even in purely visual stimulation.
This project demonstrates the feasibility of a comparative fMRI approach to visuo-vestibular networks. It contributes to the characterization of the cortical multisensory integration network, to a better understanding of the specialization of certain regions in the perception of self-motion, and to the validation of the rhesus macaque as a relevant model due to functional homology with humans. This work paves the way for electrophysiological studies in non-human primates, to explore in greater detail the dynamics of the regions identified. It also lays the foundations for new experimental protocols integrating oculometric measurements to address the perceptual dimension of multisensory integration. In humans, this research could be extended to the study of the impact of gravity or aging, opening up clinical prospects for the diagnosis and rehabilitation of vestibular disorders.
7 octobre 2025

Soutenance de thèse · invité par Tim Masquelier

PhD defense:
improving learning in spiking neural networks

Ilyass Hammouamri

Mardi 7 octobre 2025 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Computation in the brain relies on a multitude of complex neural mechanisms. While these mechanisms have been extensively studied from a neuroscience perspective, their integration into artificial neural network models to enhance learning capabilities remains underexplored. Current state-of-the-art models achieve remarkable performance on various tasks by employing complex mechanisms that differ from those found in the brain and are instead tailored to current hardware, which requires increasingly expensive computational resources. We argue that the mechanisms observed in biological neural systems could enable comparable performance while offering improved efficiency, robustness, and other benefits. Although some theoretical work has explored the computational capabilities of neural mechanisms such as synaptic transmission delays, there is a clear need for practical methods that enable the learning of these mechanisms in spiking neural networks within a machine learning context.

In this thesis, we introduce novel methods and algorithms for incorporating neural mechanisms?specifically threshold modulation and synaptic transmission delays?into spiking neural networks. We demonstrate how these mechanisms can be implemented as trainable parameters and propose methods for their learning. Our experimental results show that the inclusion of these biologically inspired mechanisms can significantly enhance the learning capacity and functional performance of SNNs across various tasks.
23 septembre 2025

Conférence CerCo

Efficient neural coding of complex sounds:
evidence from intracranial recordings during naturalistic listening

Jeremie Ginzburg
Centre for Research in Brain, Language and Music (CRBLM), and International Laboratory for Brain Music and Sound Research (BRAMS), Montreal, Canada

Mardi 23 septembre 2025 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Humans effortlessly distinguish speech from music, but the neural basis of this categorization remains debated. Here, we combined intracranial recordings in humans with behavioral categorization of speech or music taken from a naturalistic movie soundtrack to test whether the encoding of spectrotemporal modulation (STM) acoustic features is sufficient to categorize the two classes. We show that primarily temporal and primarily spectral modulation patterns characterize speech and music, respectively, and that non-primary auditory regions robustly track these acoustic features over time. Critically, cortical representations of STMs predicted perceptual judgments gathered in an independent sample. Finally, speech-and music-related STM representations showed stronger tracking of category-specific acoustical features in the left versus right non-primary auditory regions, respectively. These findings support a domain-general framework for auditory categorization, such that perceptual categories emerge from efficient neural coding of low-level acoustical cues, highlighting the computational relevance of STMs in shaping auditory representations that support behavior.
9 septembre 2025

Conférence CerCo

Confidence in multi-attribute choice

Oleg Solopchuk
University Medical Center Hamburg-Eppendorf

Mardi 9 septembre 2025 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Choices that balance multiple attributes involve mixed feelings. However, how this ambivalence is reflected in confidence judgments is unclear. For example, after making an exploratory choice that involves sacrificing an immediate gain, subjects might be confident that they chose a better option for long-term rewards, but not confident that it was a better option for immediate reward. Confirming previous studies, we found a significant increase in exploration with increasing trial horizon, but, contrary to our predictions, we found no difference between confidence in immediate or total reward.

We then tested how people judge separate confidence dimensions corresponding to different choice attributes in the face of a (more explicit) conflict between approach and avoidance. We found confidence judgments to be partially dissociated, with the information about aversive consequences leaking into the confidence of the appetitive dimension of a choice. We also found that choice confidence regarding pain decreases the perception of pain and choice confidence regarding reward increases momentary happiness, suggesting the need to refine accounts of affective judgments.
10 juillet 2025

Conférence CerCo

Multimodal EEG-fNIRS neurofeedback for motor imagery

Camille Muller
CerCo

Jeudi 10 juillet 2025 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Recently, the combination of several neuroimaging methods to characterize brain activity has sparked growing interest in the context of neurofeedback, i.e., guiding users to learn how to self-regulate their brain activity. In particular, integrating various portable recording techniques that measure electrical activity with EEG (electroencephalography) or hemodynamic activity with fNIRS (functional near-infrared spectroscopy) could enhance characterization of brain signals and ultimately improve neurofeedback performance. Our aim was to assess the potential of multimodal EEG-fNIRS neurofeedback for motor imagery, focusing on motor targets in the brain to stimulate neuroplasticity. The presentation will introduce the fully developed experimental platform for multimodal neurofeedback, as well as the study protocol conducted to evaluate the advantages of combining EEG and fNIRS for neurofeedback in the context of motor imagery.
30 juin 2025

Séminaire · invité par Isabelle Berry

Secure NeuroImaging in the Cloud, the SIESTA project

Robert Oostenveld /cyril Pernet/adrien Marque/arnaud Delorme/scott Makeig/camille Maumet

Lundi 30 juin 2025 · 10h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
SIESTA explores how cloud computing can revolutionize neuroimaging research. By leveraging scalable infrastructure and standardized workflows, we make complex MRI, EEG, and MEG analysis more accessible, reproducible, and efficient. This session will showcase how automated pipelines, containerized environments, and cloud-based data sharing streamline neuroimaging studies across different platforms and operating systems.

Join us on June 30th in Toulouse to see how cutting-edge computing can power your research, simplify collaboration, and push the boundaries of medical imaging.
Registration

There?s no fee, but if you would like to get a (free) lunch, please email Adrien.

Location and date

June 30th, 2025, Toulouse CerCo laboratory, Baudot building, first floor conference room (not ground floor)Program

10:00 ? Isabelle Berry ? Opening statements

10:05 ? Robert Oostenveld ? Introduction to the SIESTA project

10:20 ? Cyril Pernet ? Data privacy in neuroimaging

11:00 ? Adrien Marque and Nathalie Vaysierre ? An example fMRI pipeline in the SIESTA framework

11:40 ? Arnaud Delorme ? EEG pipelines and the SIESTA, and BrainLife cloud computing solutions

12:00 ? Scott Makeig ? NEMAR, HED, and NSG cloud computing solutions

12:20 ? Lunch (included for participants but email Adrien)

1:20 ? Camille Maumet (remotely) ? Reproducible NeuroImaging - a case for automated pipelines (to be confirmed)

1:50 ? Jan-Mathijs Schoffelen and Marcel Zwiers (remotely) ? SIESTA advanced methods and tips and tricks

2:20 ? Round table and general discussion led by Robert Oostenveld

3:00 ? Close
27 juin 2025

Conférence CerCo

Exploring motor planning efficiency though functional connectivity analyses

Leonardo Cano
Laboratory of Neurosciences and Applied Technologies - National University of Tucumán

Vendredi 27 juin 2025 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
This lecture will present a study using a bivariate analysis method to assess functional connectivity with EEG and EMG signals, applied to the field of motor control. The primary aim was to identify reliable biomarkers that quantify the relationship between motor decision-making and motor planning efficiency. To achieve this, an experimental paradigm involving both simple and complex motor reaction tasks was developed, in which participants responded with hand movements toward devices displaying visual stimuli of varying colors. Corticomuscular coherence (CMC) was computed to evaluate connectivity between motor cortical regions and the muscles involved during task preparation and execution. In this presentation, we will explore how different phases of reaction time can be identified, how the communication mechanisms between the brain and muscles involved in motor planning can be quantified, and finally, how the relationship between planning efficiency and functional connectivity can be modeled.
Leonardo Cano is a researcher and professor from Argentina with a strong passion for movement and sport sciences. He holds a BSc in Physical Education and a PhD in Biological Sciences. He currently teaches Anatomy at the National University of Tucumán and conducts research at the Laboratory of Neurosciences and Applied Technologies (LINTEC). His work focuses on the study of motor control through electrophysiological biomarkers, aiming to monitor, quantify, and assess motor activity in the context of motor decision-making.
26 juin 2025

Conférence CerCo

A walkthrough of the editorial processes and tips on how to write a good paper

Troby Ka-yan Lui
Springer/Nature Heidelberg

Jeudi 26 juin 2025 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Disseminating your work through scientific publishing is a vital part of research. However, scientific publishing can appear daunting when one is not familiar with the underlying editorial and peer review processes.
In this presentation, I will explain the role of a scientific editor and walk you through the editorial processes at a journal, using Communications Psychology and its sister Nature Portfolio journals (including Nature, Nature Human Behaviour, Nature Neuroscience, Nature Communications, and Scientific Reports) as examples. What do editors look for in the papers we want to publish, and how do we make decisions? We will delve into what role the journals want to play in promoting open research and what policies we put into place for that purpose. You will also get tips on how to write a paper for submission, and how to navigate peer review.
22 mai 2025

Conférence CerCo

Recent developments in transcranial alternating current stimulation (en visio)

Christoph S. Herrmann
Carl von Ossietzky, University of Oldenburg

Jeudi 22 mai 2025 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Transcranial alternating current stimulation (tACS) is a non-invasive method to modulate brain oscillations in humans. Traditionally, electrical sine waves of a certain frequency are applied via a pair of electrodes in order to elevate the amplitude of brain oscillations at that frequency. Here, we will explain three recent developments in this area. 1) In order to modulate components of the event-related potential, tACS can be temporally aligned to sensory stimuli resulting in so-called ERP-aligned tACS. 2) The spectrum of EEG activity comprises oscillatory (periodic) as well as aperiodic activity, referred to as 1/f activity. We will introduce the notion of disentangling these two types of activity and report how tACS interferes them. 3) Recently, temporal interference stimulation (TIS) has been developed in order to stimulate deep brain regions without stimulating superficial regions more strongly. This method applies two different sinusoidal electric oscillations (e.g. 1000 and 1010 Hz) via two pairs of electrodes and is thought to modulate brain activity at the difference of the two frequencies (beat frequency, 10 Hz). This would allow to remove the artefact of electrical stimulation with a low-pass filter in order to investigate the EEG during stimulation. We will demonstrate that this requires the absence of non-linearities which are common in some setups.
10 avril 2025

Conférence CerCo

Conference with Multiple presenters from IRIT - Institut de Recherche en Informatique de Toulouse

Intertoulouse Exchanges (ite) - Irit
CerCo & IRIT (Institut de Recherche en Informatique de Toulouse)

Jeudi 10 avril 2025 · 10h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Programme prévisionnel

10h - Dynamic Epistemic Logic - Exploring asynchrony and proofs by Clara Lerouvillois

10h45 - Rational Capability in Concurrent Games by Yinfeng Li

11h30 -Minimal change in Modal Logic S5 by Carlos Aguilera Ventura

12h20 - Lunch Break

14h - Analogy for Frame Semantics - Van Duy NGO

14h45 - Explainability in Spiking Neural Networks - Aditya Kar
2024 38
19 décembre 2024

Soutenance de thèse · invité par Isabelle Berry Souhaite Vivement Votre Venue

Classification d'images augmentées par apprentissage et géométrie de l'information.

Adrien Marque
CerCo et ENAC

Jeudi 19 décembre 2024 · 17h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Les images augmentées sont des images dont les pixels sont des matrices symétriques définies positives. En machine learning et statistique, les algorithmes les plus pertinents, les plus efficaces pour classifier des images sont les réseaux de neurones convolutionnels (CNN) mais ils ne s?appliquent qu?à des images classiques. Aussi nous avons dû implémenter notre propre réseau de neurones (en CUDAC++) avec l?originalité d?une étape de pré-traitement des données spécialement basée sur la géométrie de l?information.
En effet, en calculant le logarithme naturel de l?ensemble des matrices symétriques définies
positives cela remet les données dans un espace Euclidien acceptable par un CNN que nous avons ensuite appliqué à des exemples
- météorologique (faisabilité d?une trajectoire de drone en fonction de la carte des vents),
- aéronautique (prédiction de l?évolution du trafic aérien en fonction d?actions sur sa complexité)
- médical (prédiction précoce d?évolution des images de sclérose en plaques en situation d?essai thérapeutique)
19 décembre 2024

Conférence CerCo

conference (in english) about AI and medical imaging

Nidhal C.bouaynaya
ROWAN University - first Associate Vice-President for Artificial Intelligence (AI) - Prof of Electrical and Computer engineering

Jeudi 19 décembre 2024 · 11h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Dr. Bouaynaya's research interests are in Big Data Analytics, Machine Learning, Artificial Intelligence and Mathematical Optimization.
6 décembre 2024

Soutenance d'HDR

Soutenance d'HDR

Sylvain Crémoux

Vendredi 6 décembre 2024 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Résumé :
Mes travaux de recherche s?articulent autour de deux thématiques abordées jusqu?à présent de manière séparée : la compréhension des corrélats neuro-biomécaniques de l?action motrice et celle des corrélats neurocognitifs de la perception pour l?action. Une rétrospective de ces travaux est présentée dans les deux premiers chapitres. L?influence réciproque de l?action et de la perception invite à combiner ces deux approches afin de mieux comprendre les mécanismes neuro-biomécaniques engagés dans le couplage perception-action. Dans cette perspective, le troisième chapitre présente une approche originale se basant sur les théories du codage prédictif, qui considèrent que l?environnement est perçu au travers des conséquences sensorielles d?une action afin de minimiser l?erreur de prédiction sensorielle. Cependant, une même action motrice peut-être réalisée à partir d?une infinité d?activations musculaires. Afin d?en simplifier le contrôle, le système nerveux regroupe les activations musculaires sous la forme de primitives d?action, i.e., des modules fonctionnels de base permettant de générer un large répertoire de mouvement. Bien qu?évoqué dans la littérature, aucun modèle neurocognitif du couplage perception-action ne détermine les conséquences sensorielles de l?action à partir de ces primitives d?action. Nos prochains travaux de recherche viseront à mettre en ?uvre cette nouvelle approche théorique et méthodologique afin de construire un modèle neuro-biomécanique du couplage perception-action permettant de mieux comprendre l?interaction entre notre capacité à construire des représentations de notre environnement et notre capacité à y agir.

Jury:
Bastien Berret, Professeur des Universités Université Paris Saclay Rapporteur
Aymeric Guillot, Professeur des Universités Université Claude Bernard Lyon 1, Rapporteur
Raphael Zory, Professeur des Universités, Université Côte d?Azur, Rapporteur
Isabelle Loubinoux, Directrice de Recherche INSERM, Université de Toulouse, Examinatrice
Jessica Tallet, Maitresse de Conférences - HDR, Université de Toulouse, Marraine


Cordialement,
2 décembre 2024

Conférence CerCo

Quantum based sensors:
application to neurophysiological and pathological activities

Dr Etienne Labyt
CMO MAG4Health

Lundi 2 décembre 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Parmi les méthodes utilisées pour étudier les activités neurophysiologiques et les maladies neurologiques, la MagnetoEncéphaloGraphie (MEG) est un outil de choix pour enregistrer les champs magnétiques liés aux activités neuronales. Le MEG offre une très haute résolution temporelle et est capable de localiser avec précision les sources cérébrales. Contrairement à l?électroencéphalographie (EEG), la MEG n?est pas affectée par la résistivité du crâne et des sinus, qui interfère avec les signaux de l?EEG. Pour cette raison, le MEG est largement utilisée en chirurgie de l?épilepsie et dans la cartographie fonctionnelle pré-chirurgicale mais aussi en neurosciences. Il y a un intérêt croissant de la MEG pour le diagnostic et le suivi de la maladie de Parkinson, la maladie d?Alzheimer et les démences apparentées, les troubles psychiatriques...
Jusqu?à il y a quelques années, le MEG était uniquement basée sur une technologie de détection cryogénique, imposant de fortes contraintes techniques et des coûts élevés, limitant son utilisation. De nouveaux capteurs ne nécessitant pas de cryogénie, appelés magnétomètres à pompage optique (OPM), peuvent désormais être utilisés pour la MEG. Les OPM à base d?alcalins doivent être chauffés (au-dessus de 100 °C) mais peuvent être portés proche du cuir chevelu.
MAG4Health a développé un OPM à base d?hélium (HeOPM) qui ne nécessite ni chauffage ni refroidissement, et qui peut être porté confortablement sur le cuir chevelu, de la même manière que des électrodes EEG, même pour des enregistrements de longue durée. Cela simplifie grandement l?utilisation du MEG et la rend plus abordable. Actuellement, les dispositifs HeOPM MEG sont disponibles pour la recherche et actuellement, l?approbation de la FDA et la certification CE pour les utilisations cliniques sont en cours d?examen.
Nous avons utilisé l?HeOPM MEG pour enregistrer diverses activités cérébrales ainsi que des pointes épileptiques. Chez un patient, nous avons enregistré une activité épileptique simultanément à l?EEG intracerebral. Au-delà de l?exploration de l?activité cérébrale, l?HeOPM MEG a également été utilisée pour enregistrer les activités cardiaques ou musculaires. En effet, comme les HeOPMs sont des capteurs portables qui peuvent être placés n?importe où sur le corps, ils peuvent être utilisés pour enregistrer tous les champs magnétiques liés aux activités bioélectriques du corps telles que celles provenant de la rétine, des nerfs périphériques, du tractus gastro-intestinal, du c?ur et du cerveau f?tal, etc....
26 novembre 2024

Conférence CerCo

Workshop on oscillations and traveling waves

Several Speakers - See Abstract
CerCo, INT (Marseille), Université Lyon, Université Paris Cité

Mardi 26 novembre 2024 · 9h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
This workshop will be about oscillations and traveling waves, and it will take place from 14h30 to 18h30 on Monday 25th, and from 9h30 to 12h30 on Tuesday 26th. The goal is to have a very informal environment with plenty of interactions during the talks. The speakers are: Laura Dugué and Kirsten Petras (Paris); Matteo di Volo (Lyon); Frederic Chavane (Marseille); Mehdi Senoussi (CLLE); Jakob Schwenk, Martina Pasqualetti and Gregor Thut (CerCo).

In addition, on the evening of the 25th, from 17h30 to 18h30, we'll have two round table sessions:
17h30 to 18h00 : "Growing up in Science" - aimed to students but also PIs, to talk about career possibilities in academia with Laura Dugué and Fredo Chavane, both ex members of the section 26 of the CNRS;
18h00 to 18h30 : "handling a research group", to talk about issues and problematic when dealing with the management of a research group (open to young PIs, but also students and senior PIs).
25 novembre 2024

Conférence CerCo

Workshop on oscillations and traveling waves

Several Speakers - See Abstract
CerCo, INT (Marseille), Université Lyon, Université Paris Cité

Lundi 25 novembre 2024 · 9h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
This workshop will be about oscillations and traveling waves, and it will take place from 14h30 to 18h30 on Monday 25th, and from 9h30 to 12h30 on Tuesday 26th. The goal is to have a very informal environment with plenty of interactions during the talks. The speakers are: Laura Dugué and Kirsten Petras (Paris); Matteo di Volo (Lyon); Frederic Chavane (Marseille); Mehdi Senoussi (CLLE); Jakob Schwenk, Martina Pasqualetti and Gregor Thut (CerCo).

In addition, on the evening of the 25th, from 17h30 to 18h30, we'll have two round table sessions:
17h30 to 18h00 : "Growing up in Science" - aimed to students but also PIs, to talk about career possibilities in academia with Laura Dugué and Fredo Chavane, both ex members of the section 26 of the CNRS;
18h00 to 18h30 : "handling a research group", to talk about issues and problematic when dealing with the management of a research group (open to young PIs, but also students and senior PIs).
25 novembre 2024

Conférence CerCo

Workshop on oscillations and traveling waves

Several Speakers - See Abstract
CerCo, INT (Marseille), Université Lyon, Université Paris Cité

Lundi 25 novembre 2024 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
This workshop will be about oscillations and traveling waves, and it will take place from 14h30 to 18h30 on Monday 25th, and from 9h30 to 12h30 on Tuesday 26th. The goal is to have a very informal environment with plenty of interactions during the talks. The speakers are: Laura Dugué and Kirsten Petras (Paris); Matteo di Volo (Lyon); Frederic Chavane (Marseille); Mehdi Senoussi (CLLE); Jakob Schwenk, Martina Pasqualetti and Gregor Thut (CerCo).

In addition, on the evening of the 25th, from 17h30 to 18h30, we'll have two round table sessions:
17h30 to 18h00 : "Growing up in Science" - aimed to students but also PIs, to talk about career possibilities in academia with Laura Dugué and Fredo Chavane, both ex members of the section 26 of the CNRS;
18h00 to 18h30 : "handling a research group", to talk about issues and problematic when dealing with the management of a research group (open to young PIs, but also students and senior PIs).
7 novembre 2024

Séminaire · invité par Cpu

Mind-body connection:
how does perception shape the course of physical fatigue?

Pierre-marie Matta
CerCo - CNRS

Jeudi 7 novembre 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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5 novembre 2024

Séminaire · invité par Young Scientists Talks (yst)

A casual introduction to epistemic logic

Quentin Gougeon
Institut de Recherche en Informatique de Toulouse (IRIT)

Mardi 5 novembre 2024 · 1400 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Epistemic logic is a symbolic framework that aims to capture the formal properties of knowledge, belief, and related concepts. In this talk, I will give an overview of the history of the field, its key aspects, and highlight its connection to artificial intelligence, philosophy and cognition. I will also give a few words about recent research and promising directions.
22 octobre 2024

Séminaire · invité par Young Scientists Talks (yst)

Courting conflict:
understanding Drosophila reproduction in an intense aggressive context

Anthony Defert
Centre de Recherches sur la Cognition Animale (CRCA), Toulouse

Mardi 22 octobre 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
In the wild, resources such as food, territory, and reproductive partners are the focus of intense competition among animals. These resources play a crucial role in an individual's survival and fitness, leading animals to adopt various strategies to overcome competition. In the context of reproduction, and in line with Bateman's principle, males and females engage in this competition differently: females select males with the best adaptive traits, while males compete among themselves to secure offspring. This rivalry is widespread across many living organisms, and insects are no exception. In insects, male-male sperm competition occurs at several stages: before, during, and after mating. Typically, before mating, males display aggressive behaviors, ranging from threatening rivals to physical attacks, in order to gain access to females. During and after mating, males employ mate-guarding strategies to prevent their mate from copulating with other males, thus ensuring the paternity of their offspring. While some studies have shown that the most aggressive males secure preferential access to females and, consequently, reproduction, few of them have explored the potential impact of aggression on mate-guarding strategies. Therefore, we aim to investigate whether a high level of aggression provides an advantage not only in obtaining mating partners but also in preventing them from mating with others. To address this question, we study the reproductive behavior of a strain of Drosophila melanogaster selected for its highly intense aggressive traits.
22 octobre 2024

Séminaire · invité par Young Scientists Talks (yst)

Courting conflict:
understanding Drosophila reproduction in an intense aggressive context

Anthony Defert
Centre de Recherches sur la Cognition Animale (CRCA)

Mardi 22 octobre 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
In the wild, resources such as food, territory, and reproductive partners are the focus of intense competition among animals. These resources play a crucial role in an individual's survival and fitness, leading animals to adopt various strategies to overcome competition. In the context of reproduction, and in line with Bateman's principle, males and females engage in this competition differently: females select males with the best adaptive traits, while males compete among themselves to secure offspring. This rivalry is widespread across many living organisms, and insects are no exception. In insects, male-male sperm competition occurs at several stages: before, during, and after mating. Typically, before mating, males display aggressive behaviors, ranging from threatening rivals to physical attacks, in order to gain access to females. During and after mating, males employ mate-guarding strategies to prevent their mate from copulating with other males, thus ensuring the paternity of their offspring. While some studies have shown that the most aggressive males secure preferential access to females and, consequently, reproduction, few of them have explored the potential impact of aggression on mate-guarding strategies. Therefore, we aim to investigate whether a high level of aggression provides an advantage not only in obtaining mating partners but also in preventing them from mating with others. To address this question, we study the reproductive behavior of a strain of Drosophila melanogaster selected for its highly intense aggressive traits.
18 octobre 2024

Conférence CerCo

Le Système Nerveux Autonome, de l'évaluation clinique à la recherche dans le domaine spatial // The Autonomic Nervous System, from clinical assessment to research in the space field

Anne Pavy-le Traon
CHU Toulouse // MEDES

Vendredi 18 octobre 2024 · 12h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
A l'occasion de la présentation de ses travaux de recherche, Anne Pavy-Le Traon présentera les techniques d'exploration du Système Nerveux Autonome (SNA) en clinique et son intérêt diagnostic et pronostic. Un focus sera ensuite fait sur les modifications neuro-ophtalmologiques en microgravité et le rôle possible de la Pression intracrânienne sur l'activité sympathique.

On the occasion of the presentation of her research activities, Anne Pavy-Le Traon will present the techniques of exploration of the Autonomic Nervous System (ANS) in clinic and its diagnostic and prognostic interest. A focus will then be made on the neuro-ophthalmological modifications in microgravity and the possible role of intracranial pressure on sympathetic activity.
17 octobre 2024

Séminaire · invité par Rufin Vanrullen

The shape of life:
learning qualitative representations of biological dynamical systems

Matt Ricci
Hebrew University of Jerusalem

Jeudi 17 octobre 2024 · 11h Salle de réunion 2eme (Pavillon Baudot), Hôpital Purpan

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Résumé
Contemporary machine learning has delivered important insights into the structure and function of complex biological systems. Easily available tools help us decode how electrical activity propagates in a neural circuit, how a network of genes interacts, and how cells communicate in a section of tissue. But what happens when neurons in that circuit die, one of those genes mutates, or the tissue changes shape? If we cannot generalize our knowledge to these new scenarios, then we are left only with a series of isolated examples instead of a comprehensive understanding of biological function and its relation to health and disease. In this talk, I describe an ongoing research program that tackles this challenge by using tools from data science, dynamical systems theory and applied topology to predict how living systems behave under conditions of changing parameters. Particular attention is given to predicting when these systems undergo qualitative shifts in function: when the ?shape? of their behavior alters fundamentally. Throughout, we will consider the realistic case of noisy data generated from systems whose underlying equations are unknown. I first describe work which uses learned universal embeddings of low-dimensional dynamical systems to classify simple circuits by their function. Next, I demonstrate how augmenting dynamical data with topologically equivalent samples can help build a robust detector of oscillations which is then applied to the classification of proliferation vs differentiation dynamics in single-cell data of the pancreas. We then generalize to the case of spatiotemporal dynamics, where I outline recent work on building reduced-order parametric models of partial differential equations, with applications to spatial patterning in the ocellated lizard. I will conclude with some future directions, especially our goal of ?closing the loop? back to biology with the development of biologically-realistic learning algorithms.
11 octobre 2024

Soutenance de thèse

Restauration des fonctions cognitives et perceptives chez l'enfant sourd implanté cochléaire :
étude comportementale en fNIRS

Anne Lasfargues Delannoy
CerCo

Vendredi 11 octobre 2024 · 13h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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7 octobre 2024

Conférence CerCo

Les processus cognitifs en situation extrême.

Prof. Vincent Bounes
Chef de pôle médecine d'urgences CHU Purpan

Lundi 7 octobre 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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7 octobre 2024

Conférence CerCo

Les processus cognitifs en situation extrême

Prof. Vincent Bounes
Chef de pôle médecine d?urgences CHU Purpan

Lundi 7 octobre 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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30 septembre 2024

Conférence CerCo

David Dupret (oxford)

Lundi 30 septembre 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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24 septembre 2024

Soutenance de thèse · invité par Tim Masquelier

PhD defense:
Optical flow estimation from event-based cameras and spiking neural networks

Javier Cuadrado
CERCO

Mardi 24 septembre 2024 · 9h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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10 juillet 2024

Conférence CerCo

The Gestural Origin of Language Specialization of the brain :
Insight from Primatology

Adrien Meguerditchian
CRPN, CNRS/Université Aix-Marseille, Marseille

Mercredi 10 juillet 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Language is an unique communicative system involving hemispheric lateralization of the brain. To discuss the question of its origins, I will highlight the works on the communicative gestures in our primate cousins and their brain correlates. Indeed, nonhuman primates communicate mostly communicate not only with a rich vocal repertoire but also with manual and body gestures. In the last 20 years, we investigated this gestural system in the baboons Papio anubis, an Old World monkey species, as well as its lateralization and cortical correlates across development, using both ethological, psychology and longitudinal noninvasive in vivo brain imaging approach (MRI). In the present talk, I will summarize our main findings showing similar key intentional, referential ?domain general? properties of language as well as some similar underlying structural hemispheric specialization including Broca, the Planum Temporale and the STS. I will also present our recent MRI longitudinal work documenting their brain ontogeny from birth and how they pave the way for the further emergence of gesture lateralization across development.
25 juin 2024

Conférence CerCo

What vs where in electromagnetic brain imaging

Alain De Cheveigné
ENS Paris, Laboratoire des Systèmes Perceptifs

Mardi 25 juin 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
To understand the brain, we need to observe the nature and dynamics of the activity (the ?what?), and the location or distribution of its sources (the ?where?). I'll present a new approach in which these two elements are derived in parallel from separate columns of a data-driven analysis matrix. A subset of columns enhances the activity of interest, and its complement defines spatial filters (?null filters?) that suppress that activity . Each null filter is combined with an anatomy-dependent source model to estimate a set of locations within the sources space in which the source might reside (the ?zero set? of that filter) and the final estimate is derived from the intersection of zero sets. There is no theoretical limit to the accuracy with which the location of a source can be estimated in this way, but practical limits may arise from noise in the data, imperfect calibration, or an incomplete or inaccurate source model.
13 juin 2024

Séminaire · invité par Cpu Seminar

Age-related differences in noradrenergic function assessed with cognitive pupillometry

Adrian Ruiz-chiapello
CerCo - Presage team

Jeudi 13 juin 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The locus coeruleus (LC) is a brainstem nucleus located in the dorsal part of the pons. It is the major source of noradrenaline (NA) in the central nervous system, and the sole source in the forebrain. NA modulates arousal, attention, inhibitory control, cognitive flexibility, memory encoding and retrieval, and also autonomic functions like blood pressure and pupil dynamics. LC neurons are the very first site of hyperphosphorylated tau aggregates, which are one of the hallmarks of Alzheimer's disease (AD). Early pathology in the LC might result in NA release imbalance and therefore in impairment of NA-regulated cognitive processes. Pupillometry is used in our study as a non-invasive marker of NA release and LC activity. Pupil size was measured in 98 healthy participants (49 young: age = 23.0 years ± 2.6 , 49 older: age = 69.3 ± 6.8) who underwent a 2-minute passive gaze fixation task and a visual object categorization task, where various objects embedded in scenes were presented during 100ms. Their ability to recognize these images was measured the day after. We found that pupil size was smaller in older individuals, and that task-evoked pupil dilation was altered with age. Moreover pupil dilation during scene encoding was higher when scenes were successfully recollected the day after, in young but not older individuals. Our work is coherent with previous hypotheses concerning age-related alterations in encephalic NA levels, and suggests a link between these alterations and memory decline. We propose that pupillometry could be used as a tool to evaluate noradenergic imbalance in aging, which may be related with neuronal tau pathology.
13 juin 2024

Séminaire · invité par Cpu Seminar

Age-related differences in noradrenergic function assessed with cognitive pupillometry

Adrian Ruiz-chiapello
CerCo - Presage team

Jeudi 13 juin 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The locus coeruleus (LC) is a brainstem nucleus located in the dorsal part of the pons. It is the major source of noradrenaline (NA) in the central nervous system, and the sole source in the forebrain. NA modulates arousal, attention, inhibitory control, cognitive flexibility, memory encoding and retrieval, and also autonomic functions like blood pressure and pupil dynamics. LC neurons are the very first site of hyperphosphorylated tau aggregates, which are one of the hallmarks of Alzheimer's disease (AD). Early pathology in the LC might result in NA release imbalance and therefore in impairment of NA-regulated cognitive processes. Pupillometry is used in our study as a non-invasive marker of NA release and LC activity. Pupil size was measured in 98 healthy participants (49 young: age = 23.0 years ± 2.6 , 49 older: age = 69.3 ± 6.8) who underwent a 2-minute passive gaze fixation task and a visual object categorization task, where various objects embedded in scenes were presented during 100ms. Their ability to recognize these images was measured the day after. We found that pupil size was smaller in older individuals, and that task-evoked pupil dilation was altered with age. Moreover pupil dilation during scene encoding was higher when scenes were successfully recollected the day after, in young but not older individuals. Our work is coherent with previous hypotheses concerning age-related alterations in encephalic NA levels, and suggests a link between these alterations and memory decline. We propose that pupillometry could be used as a tool to evaluate noradenergic imbalance in aging, which may be related with neuronal tau pathology.
23 mai 2024

Soutenance de thèse · invité par Robin Baures Et Sylvain Cremoux

Influence de l'action sur notre perception temporelle:
apport d'une tâche d'extrapolation du mouvement visuel

Xuening Li
Soutenance de thèse

Jeudi 23 mai 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Visual motion extrapolation (VME), i.e. the ability to predict object motion when occluded, is supposed to rely on a cortical network involving motor cortices. In daily life, VME is almost always carried out concurrently to other tasks, especially, motor action, known to distort the visual perception. In this thesis, three experiments were carried out to better understand action?s influence on VME and the underlying neural mechanism. The first two experiments used a prediction-motion task to reveal that VME was biased only when action was performed during the occlusion period. Third experiment used EEG to investigate underlying neural mechanisms. Beta power recorded over the sensorimotor cortex decreased until action time, which associated with action related information and attention allocation. Beta power recorded over the premotor and supplementary motor cortex increased before the target?s reappearance. Such results are supposed to reflect temporal prediction. Significantly, modulation of low frequency bands power recorded in the visual cortex is linked to the encoding and propagation of prediction errors from the predictive coding point of view.
In conclusion, motor action and VME may share the common structures as motor and visual cortical structures, which biased influence of the motor action task on the temporal estimation in a VEM task.

Jury:
Jennifer Coull
Julien Bastin
Luca Battaglini
Jerome Barral
23 mai 2024

Soutenance de thèse · invité par Robin Baures Et Sylvain Cremoux

Influence de l'action sur notre perception temporelle:
apport d'une tâche d'extrapolation du mouvement visuel

Xuening Li
Soutenance de thèse

Jeudi 23 mai 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Visual motion extrapolation (VME), i.e. the ability to predict object motion when occluded, is supposed to rely on a cortical network involving motor cortices. In daily life, VME is almost always carried out concurrently to other tasks, especially, motor action, known to distort the visual perception. In this thesis, three experiments were carried out to better understand action?s influence on VME and the underlying neural mechanism. The first two experiments used a prediction-motion task to reveal that VME was biased only when action was performed during the occlusion period. Third experiment used EEG to investigate underlying neural mechanisms. Beta power recorded over the sensorimotor cortex decreased until action time, which associated with action related information and attention allocation. Beta power recorded over the premotor and supplementary motor cortex increased before the target?s reappearance. Such results are supposed to reflect temporal prediction. Significantly, modulation of low frequency bands power recorded in the visual cortex is linked to the encoding and propagation of prediction errors from the predictive coding point of view.
In conclusion, motor action and VME may share the common structures as motor and visual cortical structures, which biased influence of the motor action task on the temporal estimation in a VEM task.


Jury:
Jennifer Coull
Julien Bastin
Luca Battaglini
Jérome Barral
23 mai 2024

Conférence CerCo

Principles of predictive representation learning in biological neural networks

Friedemann Zenke
Friedrich Miescher Institute for Biomedical Research

Jeudi 23 mai 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Discriminating distinct objects and concepts from sensory stimuli is essential for survival. Our brains perform this processing in deep sensory networks shaped through plasticity. However, our understanding of the underlying plasticity mechanisms remains rudimentary. I will introduce Latent Predictive Learning (LPL), a plasticity model prescribing a local learning rule that combines Hebbian elements with predictive plasticity. I will show that deep neural networks equipped with LPL develop disentangled object representations without supervision. The same rule accurately captures neuronal selectivity changes observed in the primate inferotemporal cortex in response to altered visual experience. Finally, our model generalizes to spiking neural networks and naturally accounts for several experimentally observed properties of synaptic plasticity, including metaplasticity and spike-timing-dependent plasticity (STDP). LPL thus constitutes a plausible normative theory of representation learning in the brain while making concrete testable predictions.
22 mai 2024

Conférence CerCo

Perceptual Learning and Hemianopsia:
Considerations from Literature and Experimental Studies

Luca Battaglini
university of padova

Mercredi 22 mai 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Homonymous hemianopsia is a condition characterized by the loss of vision in the same half of the visual field in both eyes, resulting from a post-chiasmal lesion, often localized in the occipital cortex. This visual deficit leads to increased difficulty in daily tasks, such as watching videos, compared to individuals with normal vision. Over the years, various authors have proposed visual training aimed at reducing the size of the scotoma, exploiting perceptual learning and synaptic plasticity. In this contribution, the neurovisual training proposed in the literature will be examined, analyzing their strengths and weaknesses. In addition, the results of new experimental data collected at the Neurovisus unit of Padua will be presented, highlighting promising outcomes in the treatment of homonymous hemianopsia. These findings challenge the traditional notion of the condition as irreversible, suggesting potential therapeutic opportunities to improve vision in affected patients.
7 mai 2024

Conférence CerCo

The cost of cognition:
exploring the role of information, time & energy

Alexandre Zénon
'Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA) - CNRS

Mardi 7 mai 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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7 mai 2024

Conférence CerCo

The cost of cognition:
exploring the role of information, time & energy

Alexandre Zénon
'Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA) - CNRS

Mardi 7 mai 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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29 avril 2024

Conférence CerCo

Impact of a low glycemic index diet on metabolic disorders and cognitive decline during aging.

Lionel Carneiro
IRSD-INSERM U 1220, Toulouse

Lundi 29 avril 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Modern societies are characterized by an increase in life expectancy. This prolonged lifespan is accompanied by an increase in the number of people suffering from metabolic diseases and from cognitive decline. In fact, it is well established that diabetes and obesity are associated with worsening cognitive decline during aging. Consistent with this interaction, low glycemic index (GI) diets, developed to help diabetic people to control their blood sugar, have also been observed to benefit cognitive functions. Among the anticipated effects of these diets, the involvement of a gut-brain axis is one of the most common hypotheses. Indeed, low GI diets promote the production of ketone bodies by the liver, as well as short-chain fatty acids by the intestinal microbiota which are suggested as participating in the beneficial effects on cognition. The hypothetical mechanisms involve mitochondria, Redox balance, or even epigenetics. Noteworthily, all of these mechanisms are also described in the control of metabolism and can therefore explain the interaction between metabolic regulation and cognition. Thus, our hypothesis is that low GI diets promote the production of signals of digestive origin which participate in the brain control of metabolism via mechanisms which can also alter cognitive functions.
We therefore want to test the impact of the low GI diet on health in brain mechanisms involved in metabolic regulation and cognitive functions via the production of signals of digestive origin.
21 mars 2024

Conférence CerCo

TBA

Rachel Debs
Unité d'explorations neurophysiologiques - consultation spécialisée sommeil

Jeudi 21 mars 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
présentation suivi d'un buffet organisé par l'équipe DYNAMO
21 mars 2024

Conférence CerCo

TBA

Rachel Debs
Unité d'explorations neurophysiologiques - consultation spécialisée sommeil

Jeudi 21 mars 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Présentation suivie d'un déjeuner organisé par l'équipe Dynamo
15 mars 2024

Soutenance de thèse · invité par Tim Masquelier

PhD Defense:
Dilated Convolution with Learnable Spacings

Ismail Khalfaoui
CERCO

Vendredi 15 mars 2024 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Jury:
Nicolas Thome (rapporteur)
Emre Neftci (rapporteur)
Sylvie Chambon (examinatrice)
Gaël Richard (examinateur)
Fisher Yu (examinateur)
Tim Masquelier (directeur de thèse)
7 mars 2024

Conférence CerCo

Exploring grasp-related functions across primate species:
behavioral and electrophysiological insights

Banty Tia
RiKEN Center for Biosystems Dynamics Research (Kobe, Japon)

Jeudi 7 mars 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Exploring grasp-related functions across primates: behavioral and electrophysiological insights
Hand specialization is one of the most distinctive traits of primates. In this presentation, I will discuss research that explores the behavioral and electrophysiological correlates of grasping in humans, macaques, marmosets, and lemurs. Precision grip is generally considered a marker of dexterity, relying on both anatomical (e.g., carpal-metacarpal joint, thenar muscles) and neurophysiological features (e.g., monosynaptic corticospinal projections). However, few studies have examined its differences across species. To address this question, we designed an experimental protocol to compare human and macaque precision grip dynamics. We highlighted species-general and species-specific adjustments in kinematics and forces, along with a higher performance in humans, consistent with anatomical differences. Unlike Old World monkeys, most New World monkeys lack the ability to perform independent finger movements. To examine neuronal mechanisms in New World species and compare them with existing literature in Old World monkeys, we recorded electrocorticographic activity of sensorimotor cortex in common marmosets while they grasped and pulled various object shapes, constraining their hand configuration. Our findings demonstrated object-specific modulation of cortical activity and connectivity, indicating that fundamental control mechanisms are conserved across primates despite striking differences in dexterity. Beyond object manipulation, a significant factor influencing hand specialization is locomotion. Considering that substrate orientation drastically modifies grasping biomechanics during arboreal locomotion, we sought to characterize the neuronal counterpart of these locomotor adjustments. We examined electrocorticographic activity of frontal motor regions in common marmosets moving on a horizontal or vertical pole, revealing different contributions of cortical oscillations. Gamma (75-100 Hz) closely tuned to task dynamics, while beta (16-35 Hz) more likely reflected sensorimotor processes for postural maintenance. A similar experiment in mouse lemurs supported this hypothesis for the beta band, with motor cortex power modulation by substrate orientation at rest. Building on this evidence, my current research focuses on the integration of body axis orientation and motor commands for grasping, with the hypothesis that dynamic interactions between parietal and frontal areas mediate this process. We are conducting this research in macaques, an ideal model for this study as they allow the experiment to be repeated across different levels of dexterity. Future projects will address visuomotor functions for complex behavioral tasks in naturalistic settings, employing a cross-species comparative approach.
6 février 2024

Conférence CerCo

The encoding of abstract representations by the hippocampal-cortical complex

Timo Van Kerkoerle
Donders University

Mardi 6 février 2024 · 10h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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18 janvier 2024

Séminaire · invité par Rufin Vanrullen

Reverse Engineering Human Generalization using Artificial Intelligence

Victor Boutin
Cerco - CNRS

Jeudi 18 janvier 2024 · 10h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Although nearly every pair of objects we encounter is unique, we can consistently infer their properties based on knowledge acquired from previous experiences. This ability to transfer knowledge to new situations is called generalization and is pervasive in cognitive science. How do we generalize? In this presentation, I summarize my prior research work, underscore current results, and outline future perspectives, offering valuable insight to address this question. Cognitive scientists suggest a generalization circuit in the brain that i) extracts a disentangled and versatile representation of the sensory stimuli and ii) learns a powerful generative model of its environment. In my work, I use state-of-the-art deep learning algorithms to model those two aspects of brain computation. These models are validated through human/machine comparison on tasks inspired by cognitive science. As a case in point, I recently compared the generalization abilities of modern generative AI systems against those of humans on the one-shot drawing tasks. I demonstrate that the gap between humans and machines has started to close since the introduction of diffusion models, but that qualitative differences remain. Those differences are explainable by discrepancies in visual strategies between humans and current AI systems. The unique scientific method of my work not only allows me to uncover the computational mechanisms underpinning human generalization but also provides me with a principled path to create AI systems that are better aligned with human behavior.
17 janvier 2024

Conférence CerCo

Symposium:
from traveling waves and brain oscillations to bayesian inference and predictive coding

Frederic Chavane, Peggy Series, Martin Vinck

Mercredi 17 janvier 2024 · 9h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
In this symposium, preceding Andrea's HDR in the afternoon, three members of his jury will present their recent works. Each speaker will present for 40 minutes + 5 minutes questions. The symposium, starting at 9:30, will finish at noon.

Frederic Chavane is research director at the Institut de Neuroscience de la Timone (Marseille). His scientific interests involve Voltage Sensitive Dye Imaging (VSDI) in non-human primates, investigating horizontal connections in early sensory regions (i.e., V1) and traveling waves.

Peggy Seriès is a professor in Computational Psychiatry at the University of Edinburgh. She uses the framework of Bayesian inference and Reinforcement learning to understand the mechanisms behind several psychiatric illnesses (such as schizophrenia or depression).

Martin Vinck is a research group leader at the Ernst Struengmann Institute in Frankfurt and an International Max Planck Research School member. His work, combining electrophysiological recordings and computational modeling, focuses on understanding information processing and learning at the neuronal and brain regions levels.
17 janvier 2024

Soutenance d'HDR

Surfing cognition like a traveling wave:
from unconscious learning to predictive coding

Andrea Alamia
CerCo - CNRS

Mercredi 17 janvier 2024 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
This manuscript summarizes my previous work in cognitive neuroscience and delineates the short-term steps and the global vision for my future research interests. The overarching goal of my research career is to investigate human cognition using different tools and methods. Inter- and multi- disciplinarity are two key aspects that characterize my scientific journey, and it?s essential to keep these elements in mind when navigating through this manuscript. Several topics and methods sparkled my scientific curiosity, from unconscious learning to brain oscillations, from computational modeling to neural networks. Besides my neverending interest in human cognition, the pole star that has always set the course is the quest to find a comprehensive framework to understand the human mind. I started my journey during my phd when I explored unconscious and sequence learning, running several experiments on healthy humans (often medicine students). After establishing a methodologically sound framework to investigate unconscious processes, I explored how these influence eye movements, pupil size, and EEG recordings. Next, I set the course toward more computational shores, investigating how predictive coding could give rise to neural oscillations and traveling waves during my postdocs. Moving through differential equations and neural networks, I compared the performance of models with humans in different tasks, such as visual reasoning or artificial grammar learning. In the next years, combining all I learned along the way, I will dive into brain dynamics at different scales, understanding whether predictive coding could be the critical framework for understanding brain dynamics or, at least, traveling waves. In the long term, I plan to set sail toward more clinical-oriented applications, exploring the fascinating new world of computational psychiatry.
11 janvier 2024

Conférence CerCo

The evolution of the frontal cortex in primates :
what the sulci organization tells us.

Céline Amiez
Stem Cell And Brain Research Institute, Lyon - team : Neurobiology of executive functions

Jeudi 11 janvier 2024 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Although the relative expansion of the frontal cortex in primate evolution is generally accepted, the nature of its scaling and inter-species anatomo-functional comparisons of the frontal areas remain controversial. Indeed, a large literature has emphasized the link between the extent of gyrification, the rapid expansion of the cerebral cortex, and the complexity of the computational processing performed in a given brain. Although important, these discussions of cortical gyrification have not considered another major dimension of sulcal pattern organization, i.e. its variability. I present here results showing how the medial and the lateral frontal cortical sulcal organization has evolved through the primate order. By performing within- and across-species comparison of sulcal morphological variability based on neuroimaging anatomical scans, I provide evidences that both regions are comparable anatomically and functionally from Old World monkeys to Hominoidea, at the sole exception of the ventrolateral prefrontal cortex. In this latter region, although chimpanzees display the precursor of the human ascending sulcus rostrally limiting Broca?s area (Area 44), this precursor does not join the insula as in human. This lack of opercularization prevents the formation of the prefrontal extent of the frontal operculum, and consequently prevents the formation of the sulci featuring the pars triangularis and therefore the formation of a full Broca?s complex. These discoveries, together with recent paleontological studies suggesting that the frontal operculum appears only in Neanderthals concomitantly with modern language abilities suggests that the frontal operculum might be key to support speech functions.
2023 19
21 décembre 2023

Conférence CerCo

Multimodal units fuse-then-accumulate evidence across channels

Marcus Ghosh
Imperial College

Jeudi 21 décembre 2023 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
We continuously detect sensory data, like sights and sounds, and use this information to guide our behaviour. However, rather than relying on single sensory channels, which are noisy and can be ambiguous alone, we merge information across our senses and leverage this combined signal. In biological networks, this process (multisensory integration) is implemented by multimodal neurons which are often thought to receive the information accumulated by unimodal areas, and to fuse this across channels; an algorithm we term accumulate-then-fuse. However, it remains an open question how well this theory generalises beyond the classical tasks used to test multimodal integration. Here, we explore this by developing novel multimodal tasks and deploying probabilistic, artificial and spiking neural network models. Using these models we demonstrate that multimodal units are not necessary for accuracy or balancing speed/accuracy in classical multimodal tasks, but are critical in a novel set of tasks in which we comodulate signals across channels. We show that these comodulation tasks require multimodal units to implement an alternative fuse-then-accumulate algorithm, which excels in naturalistic settings and is optimal for a wide class of multimodal problems. Finally, we link our findings to experimental results at multiple levels; from single neurons to behaviour. Ultimately, our work suggests that multimodal neurons may fuse-then-accumulate evidence across channels, and provides novel tasks and models for exploring this in biological systems.
18 décembre 2023

Soutenance d'HDR

De l'humain dans l'espace à la perception humaine de l'espace :
j'avance donc je suis.

Alexandra Séverac Cauquil

Lundi 18 décembre 2023 · 13h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Jury :
- Suliann Ben Hamed, DR CNRS (Lyon)
- Christian Chabbert, DR CNRS (Marseille)
- Anne Charpiot, PU-PH (Strasbourg)
- Mathieu Marx, PU-PH (UT3-Toulouse)
- Yves Trotter, DR CNRS (Toulouse)
12 décembre 2023

Conférence CerCo

La voie lactée:
Influences de la composition du lait maternel sur le développement et le vieillissement neurocognitif

Florent Pittet
Neuroscience and Behavior Unit - California National Primate Research Center, University of California Davis, USA

Mardi 12 décembre 2023 · 16h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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30 novembre 2023

Séminaire · invité par Benoît Cottereau

Functional networks for social communication in the common marmoset

Audrey Dureux, Post-doc
Robarts Research Institute, Laboratory for Neural Circuits and Cognitive Control - Western University - London, Canada

Jeudi 30 novembre 2023 · 15h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Primate social communication relies on intricate neural mechanisms that allow the processing of a wide array of social cues, encompassing facial expressions, vocalizations, and complex cognitive tasks such as theory-of-mind (ToM) abilities. This presentation integrates my findings that delve into these mechanisms in the marmoset brain. Given the critical importance of such processing in primate communication, understanding this neural architecture is essential.

In my presentation, I'll delve into the marmoset's facial and vocal communication, highlighting functional networks that process these signals, both individually and conjointly. Using whole-brain ultra-high field fMRI, I investigated how marmosets process dynamic facial expressions as well as associated vocal cues. Notably, I revealed that dynamic facial expressions activate face-selective patches in occipitotemporal and frontal areas. These patches exhibited higher responses for negative faces, mirrored by the marmosets' increased respiration rates. This suggests that the perception of changeable facial expressions, vital for social communication, recruits face-selective brain patches also engaged in face detection processing. Furthermore, my work reveals that marmoset vocalizations activated auditory 'voice patches' and specific areas of the frontal cortex.
A deeper exploration into multimodal cues revealed that the combination of facial and vocal stimuli enhanced brain activity that extended beyond the sum of responses from the individual cues, recruiting additional regions. These results highlight an intricate neural network within the marmoset brain adept at processing and integrating both facial and vocal modalities.

Further into the presentation, I will shed light on the marmoset's potential ability to attribute mental states using the Frith-Happé animations. These animations depict triangles either moving randomly or suggesting that one triangle is reacting to the other triangle?s mental states. A comparison of gaze patterns and brain activations in both marmosets and humans revealed comparable brain networks and viewing patterns during the observation of ToM animations. This indicates that marmosets might attribute mental states in a way comparable to humans.

Collectively, these findings underscore the multifaceted nature of marmoset social cognition. They enhance our comprehension of the neural substrates underlying their communicative behaviors and draw evolutionary parallels between marmosets and humans. This research emphasizes the marmoset's potential as a robust nonhuman primate model for studying the nuances of social communication.
16 novembre 2023

Séminaire · invité par Cerco

Audiovisual Training in Virtual Reality Improves Auditory Spatial Adaptation in Unilateral Hearing Loss Patients

Mariam Alzaher
CerCo

Jeudi 16 novembre 2023 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
https://doi.org/10.3390/jcm12062357
9 novembre 2023

Soutenance de thèse

Traitement des indices visuels de locomotion chez les patients atteints de dégénérescence maculaire

Jade Guenot
CerCo

Jeudi 9 novembre 2023 · 15h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
8 novembre 2023

Séminaire · invité par Jade Guenot

The pupil :
a complex hub witnessing cognitive functions and visual diseases. An overview

Jean Lorenceau
INCC

Mercredi 8 novembre 2023 · 15h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
In this presentation, I shall offer a survey of the numerous recent findings concerned with pupillary activity elicited by light and/or cognitive activity, with regards to the discovery of melanopsin and intrisically photosensitive retinal ganglion cells. I'll then describe a method relying on multifocal Frequency Tagging designed to map Pupillary Response Fields in a short amount of time, and shall summarize the results of clinical studies conducted on neuropathies and retinopathies, using pupillary responses as an objective biomarker of these diseases.
30 août 2023

PhD defense

Répétition soutenance de thèse

Rachel Poulain
Multisensorialité et Mouvement en Profondeur dans le Continuum Autistique : Etude Comportementale et Neurophysiologique

Mercredi 30 août 2023 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Le fonctionnement sensoriel nous permet d?interagir avec le monde extérieur, il est ainsi
étroitement lié au développement de fonctions plus complexes notamment cognitives ou
sociales. Le Trouble du Spectre de l?Autisme (TSA) se caractérise par des difficultés dans les
interactions sociales, la présence de comportements stéréotypés et plus récemment, par des
particularités sensorielles qui s?expriment généralement par des hypo/hypersensibilités
sensorielles. Puisque la sensorialité des sujets TSA pourrait contribuer à l?intensité, voire à
l?émergence de la symptomatologie autistique, une littérature grandissante y perçoit un
potentiel étiologique. Ces particularités sensorielles ont été essentiellement caractérisées à
partir d?informations unisensorielles (e.g., visuelles ou auditives). Cependant, les informations
qui nous entourent impliquent généralement plus d?une modalité sensorielle à la fois et sont
rarement statiques. Ainsi, une attention particulière est à allouer à la manière dont les sujets
TSA intègrent des informations multisensorielles (e.g., audiovisuelles) en mouvement. Nous
avons plus particulièrement choisi d?étudier le mouvement en profondeur (en approche et en
éloignement). Celui-ci permet notamment d?éviter une menace, de poursuivre une cible et tient
un rôle important dans nos interactions sociales (e.g., s?approcher pour interagir). En outre, le
modèle dimensionnel appliqué au TSA propose une extension du spectre dans la population
générale, qui s?exprime par des traits de personnalité autistique. Ainsi, tout individu TSA et
non-TSA se placerait sur une distribution/un continuum de traits autistiques.
Ainsi, l?objectif de la présente thèse était de caractériser, sur la base d?indicateurs
comportementaux et cérébraux, l?intégration multisensorielle (IMS) de mouvement en
profondeur tout au long du continuum autistique (dans la personnalité autistique et dans le
TSA). Afin de contrôler la composante sociale, des stimuli non sociaux ont été utilisés.
Les données comportementales ont révélé davantage d'indices d?IMS dans le groupe à
personnalité autistique élevée et dans le groupe TSA, ce qui suggérerait des mécanismes d?IMS
communs à ces deux groupes. Toutefois, des comportements d?hyperréactivité face au
mouvement audiovisuel ont été retrouvés spécifiquement dans la personnalité autistique élevée
comparativement aux sujets à faible personnalité autistique. Cette hyperréactivité n'a pas été
retrouvée dans le TSA, laissant ainsi entrevoir que certains processus ne s?exprimeraient pas de
façon linéaire le long du continuum. Les données neurophysiologiques ont révélé des
différences intergroupes au niveau des composantes unisensorielles reflétant des niveaux
précoces de traitement de l?information. Concernant l?IMS, des différences dès 50 ms poststimulus ont été mises en évidence ainsi qu?un réseau de l?IMS moins étendu chez les sujets
ayant une personnalité autistique élevée comparativement aux sujets ayant une faible
personnalité autistique.
Les résultats de la présente thèse suggèrent ainsi des particularités dès les premières étapes de
traitement de l?information uni et multisensorielle pour l?ensemble du continuum autistique. Ce
travail de thèse étaye les théories grandissantes proposant un rôle crucial du fonctionnement
sensoriel dans le continuum autistique et marque l?ouverture d?un débat concernant
l?application du modèle dimensionnel au TSA.
19 juin 2023

Conférence CerCo

Thought-controlled exoskeletons for stroke rehabilitation

Imran Khan Niazi

Lundi 19 juin 2023 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
Stroke is the leading cause of adult disability in the world, and with limited effect of the current therapies, a great body of research has been conducted over the last years to find new innovative techniques to promote motor recovery in stroke rehabilitation. Brain-computer interfaces (BCIs) can potentially reestablish the disrupted motor control; likely through Hebbian mechanisms where somatosensory feedback from e.g. exoskeletons or functional electrical stimulation (FES) is casually linked with motor cortical activity. To obtain this causality, the intention to move the affected body part must be detected slightly before the movement onset to account for the time to activate e.g. the exoskeleton and for the conduction time of the feedback. Movement prediction can be obtained by detecting movement-related cortical potentials (MRCPs) that are observed prior the movement onset in the ongoing brain activity. In addition, movement-related parameters such as force and speed are encoded in the MRCP. By decoding this, it is possible to improve the control of a BCI by introducing more degrees of freedom to systems that can detect movement intentions. It could be used for providing meaningful feedback (replicated movements) to match the movement intention and/or introducing task variability in the training to maximize the retention and generalization of relearned movements.In this talk, I will outline how voluntary brain activity can be decoded and used for control of external devices (brain-computer interfaces ? BCIs). The focus will be on BCI for stroke rehabilitation.
7 juin 2023

Conférence CerCo

What can we learn from South Africa about human origins?

Dr Mirriam Tawane
Paleoanthropologist and curator, Ditsong National Museum of Natural History, Pretoria, South Africa

Mercredi 7 juin 2023 · 18h30 , Hôpital Purpan

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Résumé
The conference (in English) will take place at the Auditorium of the Museum de Toulouse, 35 allées Jules Guesde, Toulouse.

The South African fossil collection is one of the major sources of scientific information for research on the human evolutionary history in Sub-Sahara Africa and worldwide. It is among the world?s most requested natural history collection items, attracting an ever-growing stream of scholars, requesting access to original fossils hominins (i.e., our ancestors and relatives) and faunal remains. Technological advancements in the field of Palaeosciences have enabled ground-breaking research to be performed in the most fragile, distorted and incomplete fossil remains. In particular, Dr Mirriam Tawane is developing a project for creating a digital dataset of the palaeontology collection from Ditsong National Museum of Natural History of Pretoria; make available onsite and remotely the digital dataset to researchers and the general public; and print 3D models of casts for research and educational purposes.
Dr Tawane served as a council member for the National Heritage Council of South Africa. She has a Bachelor of Science degree, Honours degree and Master of Science degree in Palaeontology, and a PhD degree in Palaeoanthropology from the University of the Witwatersrand. She is the first black South African female palaeoanthropologist and she has been the source of inspiration of many young scientists in South Africa. Dr Tawane is involved in several multi-disciplinary projects in palaeoanthropology and in outreach projects. Besides being the recipient of a National Research Foundation grant for creating a digital database at the museum, she has also developed a project for taking paleosciences to the rural of areas of Taung, where she was born and where the very first fossil hominin specimen was found in Africa.
2 juin 2023

Soutenance d'HDR

Rhythmic neural and perceptual dynamics in the auditory system

Benedikt Zoefel
CerCo Toulouse

Vendredi 2 juin 2023 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
2 juin 2023

Conférence CerCo

Prediction tendencies and eye movements in support of speech tracking

Nathan Weisz
Paris-Lodron Université Salzburg

Vendredi 2 juin 2023 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Making sense of speech crucially depends on our ability to transduce the underlying physical into neural signals, that the brain can process. Damages to hearing are thus detrimental to speech perception, and pose an increasing health challenge. However, how well individuals can listen to speech is highly variable, especially when conditions become challenging. This variability is not only driven by the hearing status of the individual. In my talk, I want to illustrate recent work by my lab showing how an individual?s disposition to engage in anticipatory auditory predictions modulates measures of neural speech tracking. Additionally, I will introduce new attempts by my lab to understand the link between visuo-motor processes and speech processing. In the discussion, I intend to synthesize the results into a framework that includes multiple ?top-down systems? to support listening.
2 juin 2023

Conférence CerCo

The Perceptual And Cerebral Representation Of Natural Sounds

Bruno Giordano
Institut de Neurosciences de la Timone Marseille

Vendredi 2 juin 2023 · 10h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Every day, we are exposed to largely diverse natural sounds (e.g., whooshes, chirps, impulses, rapidly modulated harmonic signals) and recognise sound generating objects and events in the environment (e.g., a gust of wind, birds, a nail being hammered, someone speaking). Understanding their perception and neural representation has been the goal of my research since the beginning of my career. I will start this talk with a brief overview of my research portfolio ranging from the psychophysics of impacted and walked-upon objects and of musical timbre, to the neuroimaging of multisensory processes (MEG) and of emotions in voices (fMRI+MEG). I will then present two studies aiming to disentangle the relative importance of acoustic and semantic information in the perception and neuroimaging (fMRI) of natural sounds. Finally, I will describe in detail a recent analysis of behavioural and neuroimaging (fMRI) data that contrasted the representation of a wide range of computational models, ranging from acoustics to natural language processing models, to sound-to-event deep neural networks.
2 juin 2023

Conférence CerCo

The Perceptual And Cerebral Representation Of Natural Sounds

Bruno Giordano
Institut de Neurosciences de la Timone Marseille

Vendredi 2 juin 2023 · 10h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
Every day, we are exposed to largely diverse natural sounds (e.g., whooshes, chirps, impulses, rapidly modulated harmonic signals) and recognise sound generating objects and events in the environment (e.g., a gust of wind, birds, a nail being hammered, someone speaking). Understanding their perception and neural representation has been the goal of my research since the beginning of my career. I will start this talk with a brief overview of my research portfolio ranging from the psychophysics of impacted and walked-upon objects and of musical timbre, to the neuroimaging of multisensory processes (MEG) and of emotions in voices (fMRI+MEG). I will then present two studies aiming to disentangle the relative importance of acoustic and semantic information in the perception and neuroimaging (fMRI) of natural sounds. Finally, I will describe in detail a recent analysis of behavioural and neuroimaging (fMRI) data that contrasted the representation of a wide range of computational models, ranging from acoustics to natural language processing models, to sound-to-event deep neural networks.
16 mai 2023

Soutenance d'HDR · invité par Pascal Barone

Cellular underpinnings of hierarchical processing in the primate brain

Julien Vezoli
Ernst Strüngmann Institute (ESI) for Neuroscience

Mardi 16 mai 2023 · 10h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
1 mai 2023

Séminaire · invité par Moi

TEST

Moi
moi

Lundi 1 mai 2023 · 15h Salle de conférence (Pavillon Baudot), Faculté de médecine de Rangueil

Affiche
Résumé
test appli SEMINAIRES
1 mai 2023

Séminaire · invité par Moi

TEST

Moi
moi

Lundi 1 mai 2023 · 15h Salle de conférence (Pavillon Baudot), Faculté de médecine de Rangueil

Affiche
Résumé
test appli SEMINAIRES
17 janvier 2023

Conférence CerCo

Symposium:
from traveling waves and brain oscillations to bayesian inference and predictive coding

Frederic Chavane, Peggy Series, Martin Vinck

Mardi 17 janvier 2023 · 9h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
In this symposium, preceding Andrea's HDR in the afternoon, three members of his jury will present their recent works. Each speaker will present for 40 minutes + 5 minutes questions. The symposium, starting at 9:30, will finish at noon.
Frederic Chavane is research director at the Institut de Neuroscience de la Timone (Marseille). His scientific interests involve Voltage Sensitive Dye Imaging (VSDI) in non-human primates, investigating horizontal connections in early sensory regions (i.e., V1) and traveling waves.
Peggy Seriès is a professor in Computational Psychiatry at the University of Edinburgh. She uses the framework of Bayesian inference and Reinforcement learning to understand the mechanisms behind several psychiatric illnesses (such as schizophrenia or depression).
Martin Vinck is a research group leader at the Ernst Struengmann Institute in Frankfurt and an International Max Planck Research School member. His work, combining electrophysiological recordings and computational modeling, focuses on understanding information processing and learning at the neuronal and brain regions levels.
16 janvier 2023

Séminaire · invité par Tim Masquelier

Open the box of digital neuromorphic processor:
Towards effective algorithm-hardware co-design

Amir Yousefzadeh
IMEC

Lundi 16 janvier 2023 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Sparse and event-driven spiking neural network (SNN) algorithms are the ideal candidate solution for energy-efficient edge computing. Yet, with the growing complexity of SNN algorithms, it isn't easy to properly benchmark and optimize their computational cost without hardware in the loop. Although large-scale digital neuromorphic processors have been widely adopted to benchmark SNN algorithms, their black-box nature is problematic for algorithm-hardware co-optimization. In this talk, we open the black box of the digital neuromorphic processor for algorithm designers. For convenient benchmarking and optimization, we provide the energy cost of the essential neuromorphic components in SENeCA, including neuron models and learning rules. Overall, we present a practical approach to enable algorithm designers to accurately benchmark SNN algorithms and pave the way toward effective algorithm-hardware co-design.
2022 22
20 décembre 2022

Soutenance de thèse · invité par Céline Cappe

Intégration multisensorielle :
implications du thalamus et du cortex

Anne-laure Vittek
CerCo

Mardi 20 décembre 2022 · 13h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Notre perception de l?environnement est multisensorielle. Le réseau anatomique impliqué dans
l?intégration multisensorielle est multiple. L?objectif de cette thèse était d?étudier le rôle potentiel du
gyrus cingulaire postérieur, une région corticale, et du pulvinar médian, une structure sous-corticale,
dans l?intégration multisensorielle. Pour cela, des enregistrements électrophysiologiques (single-units
et local field potentials, LFP) ont été réalisés dans ces deux zones, chez deux macaques, pendant une
tâche de fixation avec présentation de stimuli auditifs, visuels et audiovisuels de différentes natures
(serpent, macaque, bruit).
Concernant le gyrus cingulaire postérieur, l?analyse des single-units précédemment réalisée avait
révélé la présence de neurones auditifs, visuels et audiovisuels. Plusieurs types de neurones
audiovisuels ont été identifiés : neurones classiques (neurones bimodaux et modulateurs) et
complexes, ces derniers n?ayant pas été décrits dans la littérature jusque-là. Les neurones audiovisuels
complexes sont des neurones dont la réponse sensorielle dépend du stimulus présenté. Ils peuvent,
par exemple, se comporter comme un neurone auditif pour un stimulus (serpent) et comme un
neurone visuel pour un autre stimulus (macaque). Nous avons montré que les neurones audiovisuels
dans le gyrus cingulaire postérieur sont principalement sub-additifs. L?analyse des LFP révèle que cette
région reçoit des informations auditives, visuelles et audiovisuelles. L?analyse dans le domaine
fréquentiel indique que ces informations sont partiellement séparées selon les bandes de fréquences.
Notamment, l?information multisensorielle est largement majoritaire dans les basses fréquences,
tandis qu?on retrouve plus d?informations unisensorielles à hautes fréquences.
Concernant le pulvinar médian, l?analyse des single-units révèle la présence de neurones unisensoriels
et multisensoriels (classiques et complexes), réalisant de l?intégration multisensorielle. L?analyse des
LFP indique que cette structure reçoit les trois informations sensorielles considérées (auditive, visuelle,
audiovisuelle), l?information multisensorielle étant majoritaire dans les basses fréquences. De plus, les
différences de proportion de signaux multisensoriels en entrée (LFP) et en sortie (single-units) du
pulvinar médian confirment que ce noyau thalamique traite l?information avant de la renvoyer, et que
son rôle ne se résume pas à un simple rôle de relai mais qu?il joue un rôle intégratif. La présence de
neurones multisensoriels qualifiés de complexes, tout comme la séparation des informations
sensorielles entre les bandes de fréquences sont à mettre en relation avec de possibles améliorations
de l?information disponible et de sa transmission entre les différentes régions du cerveau. En effet,
répartir différentes informations sur divers canaux (les fréquences) d?un seul signal (les LFP) permet
de transmettre simultanément davantage d?information, voire de cibler les régions auxquelles chaque
information est transmise si ces dernières n?utilisent que certains canaux.
12 décembre 2022

Soutenance de thèse · invité par Benoit Cottereau

Modélisation du traitement visuel de l?information lors de la locomotion à l?aide de réseaux de neurones impulsionnels bioinspirés

Paul Fricker
CerCo

Lundi 12 décembre 2022 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Le domaine de l?intelligence artificielle est en plein essor depuis de nombreuses années et définit la base de tout apprentissage s?effectuant par des systèmes informatiques. Au cours des dernières années, les réseaux de neurones se sont de plus en plus complexifiés avec un nombre de paramètres et une consommation énergétique toujours plus élevés. Certains types de réseaux de neurones artificiels restent néanmoins plus ancrés dans la biologie, les réseaux de neurones impulsionnels (SNN).

Ces réseaux reposent sur des mécanismes de communication observés entre les neurones biologiques. Une première étude se penche sur la création d?un tel réseau pour l?apprentissage des composantes de flux optique. En interfaçant ce SNN avec des entrées de données événementielles d?abord simulées, il a pu être mis en évidence les performances du réseau pour l?estimation des différentes composantes du flux optique à travers différentes conditions de bruit et de vitesse. Le même réseau a par la suite été entrainé à partir de données de navigation réelles capturées à l?aide d?une caméra événementielle.

Une seconde étude s?intéresse à la création d?un jeu de données par numérisation 3D d?environnements pour l?apprentissage du réseau. Les premiers résultats montrent que les neurones du réseau après apprentissage deviennent sélectifs aux différentes composantes du flux optique tout en restant invariant aux propriétés spatiales.
12 décembre 2022

PhD defense · invité par Tim Masquelier

PhD defense:
Theoretical framework for Time-To-First-Spike coding in Spiking Neural Networks

Lina Bonilla

Lundi 12 décembre 2022 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
7 décembre 2022

Soutenance de thèse

How to train your Global Workspace? Evaluating, and efficiently Learning Multimodal Representations

Benjamin Devillers
Thesis defense

Mercredi 7 décembre 2022 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
When learning about the world, inputs can come in various ways: images when we look around, text describing objects and their properties, audio during conversations, etc. Most of these inputs are not annotated and come together asynchronously to build a joint representation of the external world. With the recent advent of contrastive learning, state-of-the-art multimodal models heavily rely on the natural occurrence of synchronous data online: social media, Wikipedia, discussion websites, art communities, news websites, etc., have users posting multimodal publications with, in particular, text and image content. This data is produced by humans, for humans, who are assumed to have prior knowledge to understand the publications (for example, slang vocabulary, references to history and current events, pop culture, or inside knowledge of specialized communities). With recent breakthroughs in how computing chips are built and used, large models have left the world astonished with their abilities. Besides, their full potential is not fully known, and many evaluations and analyses will be required to discover all their aptitudes. While these models solely rely on the availability of online annotation, unlabeled datasets are readily available in all shapes and forms (image, video, sound, text, etc.). They could be used as an additional source of information. In parallel, neuroscientists have been studying the brain for several decades, and cognitive theories backed by experimental studies are a precious source of inspiration for artificial intelligence research. In particular, Baars? theory of the Global Workspace has recently gained popularity and provides hindsight on a multimodal integration framework.
In this thesis, we will first introduce the basis of multimodal learning; then, we will focus on already existing multimodal networks and see how they compare to unimodal networks in terms of generalization. In light of these results, we will take inspiration
from the Global Workspace cognitive theory to design a semi-supervised multimodal learning framework, which requires fewer annotations than previous frameworks for equivalent performance.
7 décembre 2022

Soutenance de thèse

How to train your Global Workspace? Evaluating, and efficiently Learning Multimodal Representations

Benjamin Devillers
Thesis defense

Mercredi 7 décembre 2022 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
When learning about the world, inputs can come in various ways: images when we look around, text describing objects and their properties, audio during conversations, etc. Most of these inputs are not annotated and come together asynchronously to build a joint representation of the external world. With the recent advent of contrastive learning, state-of-the-art multimodal models heavily rely on the natural occurrence of synchronous data online: social media, Wikipedia, discussion websites, art communities, news websites, etc., have users posting multimodal publications with, in particular, text and image content. This data is produced by humans, for humans, who are assumed to have prior knowledge to understand the publications (for example, slang vocabulary, references to history and current events, pop culture, or inside knowledge of specialized communities). With recent breakthroughs in how computing chips are built and used, large models have left the world astonished with their abilities. Besides, their full potential is not fully known, and many evaluations and analyses will be required to discover all their aptitudes. While these models solely rely on the availability of online annotation, unlabeled datasets are readily available in all shapes and forms (image, video, sound, text, etc.). They could be used as an additional source of information. In parallel, neuroscientists have been studying the brain for several decades, and cognitive theories backed by experimental studies are a precious source of inspiration for artificial intelligence research. In particular, Baars? theory of the Global Workspace has recently gained popularity and provides hindsight on a multimodal integration framework.
In this thesis, we will first introduce the basis of multimodal learning; then, we will focus on already existing multimodal networks and see how they compare to unimodal networks in terms of generalization. In light of these results, we will take inspiration
from the Global Workspace cognitive theory to design a semi-supervised multimodal learning framework, which requires fewer annotations than previous frameworks for equivalent performance.
22 novembre 2022

Conférence CerCo

Attentional control of visual input in the human brain:
On the mechanistic role of posterior brain oscillations in perception and attention

Pr Gregor Thut
directeur centre de Neuro-Imagerie Cognitive de GLASGOW

Mardi 22 novembre 2022 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
A key question in cognitive neuroscience is how brain activity orchestrates brain function. This talk will focus on the functional roles of brain oscillations. This type of brain activity is thought to reflect the assembly of neuronal elements into functional networks and can be measured using electro-/magnetoencephalography (EEG/MEG). The focus of my talk will be on those brain oscillations that relate to attentional control of visual input and perception, and how this endogenous brain-perception relationship can be controlled externally through non-invasive transcranial brain stimulation. The talk will cover work that originated with the observation that brain oscillations in the alpha frequency band (over occipito-parietal areas) at baseline predict upcoming perception. Follow-up studies explored how the different features of this alpha oscillation (frequency, amplitude, phase) relate to different aspects of perception (visual sensitivity, subjective awareness), how they are modulated by attention, how they may relate to mechanisms of information processing (sampling, gating, evidence accumulation) and whether they play a causal (mechanistic) role or represent simple correlates (epiphenomena) of perception. While situated in models of cognition and human electrophysiology, these studies also bridge to neurotechnology with the aim of developing the existing brain stimulation techniques into more powerful neuroscience tools (and clinically effective protocols), to manipulate and better understand the brain-behaviour relationship and the neural processes driving it.
22 novembre 2022

Conférence CerCo

Attentional control of visual input in the human brain:
On the mechanistic role of posterior brain oscillations in perception and attention

Pr Gregor Thut
directeur centre de Neuro-Imagerie Cognitive de GLASGOW

Mardi 22 novembre 2022 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
Résumé
A key question in cognitive neuroscience is how brain activity orchestrates brain function. This talk will focus on the functional roles of brain oscillations. This type of brain activity is thought to reflect the assembly of neuronal elements into functional networks and can be measured using electro-/magnetoencephalography (EEG/MEG). The focus of my talk will be on those brain oscillations that relate to attentional control of visual input and perception, and how this endogenous brain-perception relationship can be controlled externally through non-invasive transcranial brain stimulation. The talk will cover work that originated with the observation that brain oscillations in the alpha frequency band (over occipito-parietal areas) at baseline predict upcoming perception. Follow-up studies explored how the different features of this alpha oscillation (frequency, amplitude, phase) relate to different aspects of perception (visual sensitivity, subjective awareness), how they are modulated by attention, how they may relate to mechanisms of information processing (sampling, gating, evidence accumulation) and whether they play a causal (mechanistic) role or represent simple correlates (epiphenomena) of perception. While situated in models of cognition and human electrophysiology, these studies also bridge to neurotechnology with the aim of developing the existing brain stimulation techniques into more powerful neuroscience tools (and clinically effective protocols), to manipulate and better understand the brain-behaviour relationship and the neural processes driving it.
22 novembre 2022

Conférence CerCo

Attentional control of visual input in the human brain:
On the mechanistic role of posterior brain oscillations in perception and attention

Pr Gregor Thut
directeur centre de Neuro-Imagerie Cognitive de GLASGOW

Mardi 22 novembre 2022 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
A key question in cognitive neuroscience is how brain activity orchestrates brain function. This talk will focus on the functional roles of brain oscillations. This type of brain activity is thought to reflect the assembly of neuronal elements into functional networks and can be measured using electro-/magnetoencephalography (EEG/MEG). The focus of my talk will be on those brain oscillations that relate to attentional control of visual input and perception, and how this endogenous brain-perception relationship can be controlled externally through non-invasive transcranial brain stimulation. The talk will cover work that originated with the observation that brain oscillations in the alpha frequency band (over occipito-parietal areas) at baseline predict upcoming perception. Follow-up studies explored how the different features of this alpha oscillation (frequency, amplitude, phase) relate to different aspects of perception (visual sensitivity, subjective awareness), how they are modulated by attention, how they may relate to mechanisms of information processing (sampling, gating, evidence accumulation) and whether they play a causal (mechanistic) role or represent simple correlates (epiphenomena) of perception. While situated in models of cognition and human electrophysiology, these studies also bridge to neurotechnology with the aim of developing the existing brain stimulation techniques into more powerful neuroscience tools (and clinically effective protocols), to manipulate and better understand the brain-behaviour relationship and the neural processes driving it.
17 novembre 2022

Séminaire · invité par Emmanuel Barbeau

Emma Delhaye
Impact of objects' semantics on their episodic recognition and underlying neural substrates

Jeudi 17 novembre 2022 · 11h Salle de réunion 2eme (Pavillon Baudot), Hôpital Purpan

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Résumé
For several decades, episodic and semantic memory have been studied as two independent memory systems. Yet, recent research started to question this dissociation and to show interdependency between episodic and semantic memory. In terms of brain regions, common neural substrates have been evidenced while being historically associated with separate episodic/semantic functions, notably within the anterior temporal lobe (ATL), comprising the perirhinal cortex. I will present two studies in which the semantic properties of objects were manipulated in terms of their conceptual confusability during episodic recognition memory while using a variety of neuroimaging techniques. Study 1 used functional Magnetic Resonance Imaging (MRI) while Study 2 used structural MRI in patients presenting lesions of the perirhinal cortex (patients with Alzheimer?s disease). Across these two studies, we show evidence of an implication of the ATL in episodic memory, specifically for conceptually confusable objects. Based on results, we suggest that the role of this region may be better understood in terms of fine-grained, item-specific, processing, rather than in terms of the memory system it supports.
25 octobre 2022

Conférence CerCo

Contribution of adult-born neurons to hippocampal population dynamics.

Prof. David Dupret
Oxford University

Mardi 25 octobre 2022 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
To process information in memory, the hippocampus uses sparse population activity whereby only a small proportion of neurons are active at any point in time. The dentate gyrus (DG) supports this process by gating sensory information to the hippocampus, decorrelating these inputs into non-overlapping patterns. Intriguingly, the DG produces new excitatory neurons throughout adulthood. These adult-born dentate granule cells (abDGCs) integrate to the hippocampal circuitry within a few weeks and support various hippocampal-dependent behaviours. However, the network-level contribution made by abDGCs to hippocampal firing dynamics is unclear. In this talk, I will present recent work showing that abDGCs promote sparser hippocampal population spiking during mnemonic processing of novel stimuli. By combining triple-(DG-CA3-CA1) ensemble recordings and optogenetic interventions in behaving mice, we show that abDGCs constitute a subset of high-firing rate neurons with enhanced activity responses to novelty and strong modulation by theta oscillations. Selectively activating abDGCs in their 4-7-week post-birth period increases sparsity of hippocampal population patterns, whereas suppressing abDGCs reduces this sparsity, increases principal cell firing rates and impairs novel-object recognition with reduced dimensionality of the network firing structure, without affecting single-neuron spatial representations. Accordingly, I will discuss that adult-born granule cells transiently support sparser hippocampal population activity structure for higher-dimensional responses relevant to effective mnemonic information processing.
20 octobre 2022

Soutenance de thèse

Deep Learning and Neuroscience - a match made in heaven?

Bhavin Choksi
CerCo

Jeudi 20 octobre 2022 · 14h 15 (CEC : Centre de Enseignement et Congrès), Hôpital Purpan

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19 octobre 2022

Séminaire · invité par Rufin Vanrullen

Goals and relevance in the processing of natural scenes

Andrea De Cesarei
University of Bologna (Italy)

Mercredi 19 octobre 2022 · 11h Salle de réunion 2eme (Pavillon Baudot), Hôpital Purpan

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19 septembre 2022

Séminaire · invité par Benedikt Zoefel

Modulating human brain oscillations with transcranial alternating current stimulation

Florian Kasten
CerCo Toulouse

Lundi 19 septembre 2022 · 15h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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13 septembre 2022

Conférence CerCo

Transitional states between sleep and wake in physiological and pathological situations

Laure Peter-derex
Hospices civils de Lyon - CNRL

Mardi 13 septembre 2022 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
"Etats transitionnels entre sommeil et veille en situation physiologique et pathologique."

Trois états de vigilance sont habituellement décrits chez l?Homme: la veille, le sommeil lent et le sommeil paradoxal. Cependant, certaines situations cliniques comme les parasomnies ou l?inertie de sommeil, ainsi que des travaux expérimentaux chez l?animal et chez l?homme, suggèrent la possibilité d?inhomogénéités spatio-temporelles dans les états de vigilance. Nous avons abordé cette question en étudiant les périodes transitionnelles entre sommeil et veille, en condition physiologique et pathologique. Ces travaux reposent pour la plupart sur des enregistrements intra-cérébraux réalisés chez des patients épileptiques pharmaco-résistants bénéficiant d?un bilan pré-chirurgical stéréo-électro-encéphalographique.
En analysant l?activité de régions saines non épileptiques, nous avons observé que le processus de transition du sommeil vers la veille était un phénomène graduel, progressif, local, asynchrone, et parfois discordant, certaines régions cérébrales étant susceptibles de présenter des réactions d?éveil alors que d?autres renforcent le sommeil simultanément. Nous avons aussi montré que l?étude du phénomène de réveil était pertinente pour comprendre certaines parasomnies et quantifier l?inertie dans les hypersomnies. Dans la continuité de ces travaux, nous nous sommes intéressés à l?impact d?une activité neuronale pathologique, l?activité épileptique, sur la microstructure du sommeil et en particulier sur les réactions d?éveil. Nous avons pu montrer que l?activité paroxystique ictale et interictale perturbait la continuité du sommeil et que cette fragmentation du sommeil contribuait réciproquement à renforcer l?activité épileptique.
Ces travaux montrent la grande labilité spatiotemporelle des états de vigilance et des patterns EEG qui les caractérisent, artificiellement figés par la vision parcellaire captée par l?EEG de scalp, par l?analyse visuelle que l?on peut en faire, et par les règles de codage des stades de sommeil. Ils suggèrent aussi que les caractéristiques des périodes transitionnelles entre états de vigilance, zones frontières fragiles, sont susceptibles de constituer des marqueurs de pathologies du sommeil ou de maladies neurologiques plus généralement. Ils ouvrent enfin des perspectives en termes de compréhension des corrélats cognitifs de ces états intermédiaires et de ces micro-états locaux.


"Transitional states between sleep and wake in physiological and pathological situations."

Three states of vigilance are recognized in humans: wakefulness, rapid-eye movement sleep and non-rapid-eye-movement sleep. However, several clinical conditions such as parasomnias, para-physiological experiences such as sleep inertia, as well as experimental works in animals and humans, suggest that spatio-temporal inhomogeneity may occur within these apparently distinct vigilance states. We aimed to address this issue by studying the transitional states between sleep and wakefulness, including micro-arousals and micro-sleeps, in physiological and pathological conditions. Most of these works rely on intracerebral stereo-electro-encephalography recordings performed in patients with drug-resistant epilepsy in the context of pre-surgical workup.
By analyzing the activity of healthy non-epileptic brain areas, we have demonstrated that the transition from sleep to wake was a gradual, progressive, local, and asynchronous process, with possible discrepancies between regions showing wake-like activity and others simultaneously reinforcing sleep-like patterns. We have also shown that the study of awakening was relevant to understand some parasomnia and to quantify sleep inertia in hypersomnia. Finally, we have explored the impact of a pathological brain activity, the epileptic activity, on sleep microstructure. We were able to show that paroxysmal ictal and interictal activity disrupted sleep continuity and that, in turn, sleep fragmentation contributed to reinforce the epileptic activity.
These works show the great spatiotemporal lability of EEG patterns that characterize vigilance states, artificially frozen by the fragmented vision captured by the scalp EEG, by the limitations of visual analysis, and by the sleep scoring rules. They also suggest that the characteristics of transitions periods between vigilance states are fragile boundaries, likely to represent useful biomarkers of sleep disorders or neurological diseases. Finally, they open perspectives for the understanding of cognitive correlates of such transitional states and local microstates.
13 septembre 2022

Conférence CerCo

Predicting and Understanding Speech

Matt Davis
MRC Cognition and Brain Sciences Unit, University of Cambridge

Mardi 13 septembre 2022 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
This talk will focus on the neural mechanisms by which human listeners achieve their remarkable success at perceiving and understanding speech. In line with Bayesian inference, perception of speech is guided by prior knowledge. Neural decoding of fMRI and MEG responses during speech perception shows that sensory representations are changed by informative or uninformative prior knowledge from written text and from linguistic predictions. Our studies show interactions between sensory detail and prior knowledge that are unlike the additive effects seen in perception, or would be expected for direct neural representations of perceptual outcomes. These findings instead support predictive coding views in which evoked neural activity represents sensory prediction errors.
5 septembre 2022

Séminaire · invité par Rufin Vanrullen

Investigating prediction and delay-compensation in the neural encoding of moving objects

William Turner
University of Melbourne, Australia

Lundi 5 septembre 2022 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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5 septembre 2022

Séminaire · invité par Rufin Vanrullen

Investigating prediction and delay-compensation in the neural encoding of moving objects

William Turner
University of Melbourne, Australia

Lundi 5 septembre 2022 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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5 juillet 2022

Séminaire · invité par Caroline Fonta

Skulls to brain:
tracking the fossil hominin cerebral architecture using advanced imaging techniques and 3D modelling

Edwin De Jager, Phd Student
Biological Anthropology, Department of Archaeology, University of Cambridge, UK

Mardi 5 juillet 2022 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
ZOOM possibility :
https://univ-tlse3-fr.zoom.us/j/95718810968?pwd=YWxETlZGVkVXLzFGUFpDbitUbFkyUT09
ID de réunion : 957 1881 0968
Code secret : 547713Reconstructing the timeline and process of cerebral feature derivations in the human lineage offers us a glimpse into the behaviour of our ancestors and relatives. In order to study hominin brain evolution using the fossil record, palaeoneurologists are reliant on endocasts: replicas of the inner table of the bony braincase. The accurate identification of cerebral sulci imprints on endocasts is critical for assessing the topographic extension and structural organisation of cortical regions; however, studying these imprints remains an elusive task. The implementation of modern imaging techniques combined with methods commonly used in population-based brain atlases provides us with a solution: by creating an innovative atlas that documents and visualises sulcal imprints on extant populations, an array of new possibilities becomes available through the creation of a non-invasive and completely observer-independent method for investigating human endocranial structural organisation. This protocol presents a promising perspective for discussing critical hypotheses on the evolution of cognitive abilities among hominins.
24 mai 2022

Conférence CerCo

Perception during visual disruptions

Grace Edwards And Lina Teichmann
NIMH

Mardi 24 mai 2022 · 15h Visioconférence, Visioconférence

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Résumé
Visual perception is perceived as continuous despite frequent disruptions in our visual environment. For example, internal events, such as saccadic eye-movements, and external events, such as object occlusion temporarily prevent visual information from reaching the brain. Combining evidence from these two models of visual disruption (occlusion and saccades), we will describe what information is maintained and how it is updated across the sensory interruption.

Lina Teichmann will focus on dynamic occlusion and demonstrate how object motion is processed through perceptual gaps. Grace Edwards will then describe what pre-saccadic information is maintained across a saccade and how it interacts with post-saccadic processing in retinotopically relevant areas of the early visual cortex.

Both occlusion and saccades provide a window into how the brain bridges perceptual disruptions. Our evidence thus far suggests a role for extrapolation, integration, and potentially suppression in both models. Combining evidence from these typically separate fields enables us to determine if there is a set of mechanisms which support visual processing during visual disruptions in general.
8 mars 2022

Conférence CerCo

Crossmodal plasticity:
Recycling the multisensory scaffolding of functional brain networks

Olivier Collignon
Université de Louvain (Belgique)

Mardi 8 mars 2022 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The study of the functional organization of brain regions deprived of their preferred sensory inputs (eg. the occipital cortex of the blind or the temporal cortex in the deaf) has recently provided unprecedented new insights on the "nature versus nurture" debate on the mind/brain development. More specifically, the observation that temporal regions in the deaf or occipital regions in the blind extend their response to inputs from the remaining senses highlights the role experience plays in shaping the sensory-tuning of brain regions. However, the fact that this crossmodal plasticity follows organizational principles similar to the ones observed in the hearing or sighted brain highlights that intrinsic forces impact the development of the functional organization of the brain. In my talk, I will suggest that crossmodal plasticity builds on the multisensory scaffolding of brain networks and helps maintain the main functional homeostasis of regions deprived of their preferred sensory inputs.
11 février 2022

Conférence CerCo

VERTEX, Vertige Extreme:
a brand new research unit at Caen University on Vertigo and extreme physiology

Stéphane Besnard
Université de Normandie Explorations Fonctionnelles ORL - CHU CAEN

Vendredi 11 février 2022 · 10h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Stéphane Besnard (MD, PhD) est Maître de Conférence-PH en physiologie au CHU de Caen depuis 2007. Il a été chercheur associé à l?UMR 7260 LNCS CNRS à et membre de l?INSERM U1075 COMETE pendant 12 ans. Ses principaux sujets de recherche portent sur le système vestibulaire, l?intégration multisensorielle et le mal des transports chez les patients et dans des environnements extrêmes, ainsi que sur le développement biotechnologique associé. Vendredi il nous présentera la thématique de la toute nouvelle unité de recherche qu'il créé à l'université de Caen, Vertex, et des protocoles qui y sont développés, en particulier DEEP TIME et SENSORIEL 2.
3 février 2022

Séminaire · invité par Céline Cappe

Characterizing the mechanisms supporting cognitive flexibility for task implementation:
from computational modelling to empirical validation, and future directions

Mehdi Senoussi
Department of Experimental Psychology, Ghent University (Ghent, Belgium)

Jeudi 3 février 2022 · 14h Visioconférence, Visioconférence

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Résumé
Whether we are biking to work, writing a seminar abstract or cooking a new recipe, we need to implement sets of rules constituting the task at hand. In such situations, efficient performance depends on flexible adaptation to task demands (e.g. novelty or difficulty of the task). Previous studies have shown that neural oscillations play a critical role in such cognitive processes, but it remains unclear how these mechanisms adapt to task demands. In this seminar, I will present some modelling and empirical (behavior & EEG) work in which we investigated how oscillatory processes, i.e. frontal theta oscillations, flexibly adapt to task demands and affect behavioral performance. I will then briefly present future projects in which I want to study i) how task learning unfolds to allow such flexible adaptation, and ii) how neuromodulatory systems (e.g. noradrenaline) permit to regulate oscillations for optimal task performance.
2021 11
25 octobre 2021

Séminaire · invité par Benedikt Zoefel

The development of envelope-tACS as a hearing aid

Jules Erkens
University of Oldenburg

Lundi 25 octobre 2021 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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20 octobre 2021

Soutenance de thèse

Détection automatique multiéchelle et de grande envergure d?oscillations intracérébrales pathologiques dans l?épilepsie par réseaux de neurones artificiels

Ludovic Gardy
CerCo

Mercredi 20 octobre 2021 · 9h30 Salle de conférence (Pavillon Baudot), Visioconférence

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30 septembre 2021

Séminaire · invité par Caroline Fonta

Mapping the brain of fossil hominins:
the EndoMap project

Amélie Beaudet
Lecturer in Human Origins, Department of Archaeology, University of Cambridge

Jeudi 30 septembre 2021 · 16h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Lieu : Pavillon Baudot, salle de conférences(avec pass sanitaire) + zoom
https://zoom.us/j/92376702340?pwd=ZjYxTy9MN1c4M3l3eVUxQy9FWXdsdz09
ID de réunion : 923 7670 2340
Code secret : qMbCX2

Abstract :The EndoMap project aims to provide new insights into the timing and mode of the structural changes that shaped the human brain evolutionary history. Because brains do not fossilize, paleoneurologists have to rely on visual inspection and palpation of brain imprints preserved on the inner surface of the braincase (i.e., endocasts). As a consequence, long-standing questions on when and how human-like derived cerebral features emerged in our lineage continue to be debated. The main goal of this project is thus to assess the earliest occurrence of the human-like cerebral specificities by developing a new protocol for the computer-assisted recognition of brain imprints on fossil hominin endocasts. This goal will be achieved through the non-invasive analysis of extant human endocasts as well as the investigation of cranial remains from the African fossil hominin record coupled with the use of high-resolution imaging techniques, digital atlases and probability maps. Here we present preliminary results of the EndoMap project with the description of brain imprints in iconic fossil specimens (e.g., ?Little Foot?) and the quantification of the variation pattern in extant humans. Built upon collaborations between neuroscientists, computer scientists and palaeoanthropologists, this multidisciplinary project will provide new insights into the human brain evolutionary history.
28 septembre 2021

Conférence CerCo

In Space and Time:
Network Dynamics of a Memory Representation

David Dupret
Medical Research Council Brain Network Dynamics Unit at the University of Oxford

Mardi 28 septembre 2021 · 11am Visioconférence, Visioconférence

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19 mai 2021

Séminaire · invité par Jean-baptiste Durand

Estimating electrical hearing thresholds using eCAPs as an objective measure in cochlear implanted common marmosets

Amirouche Sadoun
Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Goettingen

Mercredi 19 mai 2021 · 11h Visioconférence, Visioconférence

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16 avril 2021

Conférence CerCo

Predictive Error-driven Learning in the Brain

Randall O'reilly
Department of Psychology, Computer Science, and the Center for Neuroscience, University of California Davis

Vendredi 16 avril 2021 · 9h Visioconférence, Visioconférence

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Résumé
How do humans learn from raw sensory experience? Throughout life, but most obviously in infancy, we learn without explicit instruction. We propose a detailed biological mechanism for the widely-embraced idea that learning is driven by the differences between predictions and actual outcomes (i.e., predictive error-driven learning).
16 avril 2021

Conférence CerCo

Automated text simplification as a reading aid for low-vision individuals

Aurelie Calabrese
INRIA, Sophia-Antipolis

Vendredi 16 avril 2021 · 11h Visioconférence, Visioconférence

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Résumé
In developed countries, the majority of people with visual impairment are legally blind, but not totally blind. Instead, they have what is referred to as low vision, commonly caused by Central visual Field Loss (CFL). This degenerative condition is caused by non-curable retinal diseases, such as Age-related Macular Degeneration (DMLA in French). Patients suffering from such pathologies will develop a blind region called scotoma, located at the center of their visual field and spanning about 20° or more. To better visualize the impact of such a large hole in your visual field, try stretching your index and little finger as far as possible from each other at arm?s length; the span is about 15°. Central vision cannot be restored and difficulty with reading becomes the primary complaint of patients seeking rehabilitation. To help CFL individuals improve their reading performance, it is necessary to investigate the underlying causes of their deficit, to then overcome them with specific adjustments.



In this presentation, I propose to address the issue of reading with CFL from a new perspective, a linguistic one, that takes into account the whole complexity of texts. I will present a series of experiments that investigate what makes a text especially complex when reading with CFL, by assessing the effect of lexical properties on reading speed. We will focus on three word properties: frequency, orthographic similarity and length. I will conclude on the relevance of this work to design text simplification tools, customised to the specific needs of readers with CFL, to be used as efficient reading aids for this population.
9 avril 2021

Conférence CerCo

PhD Defense :
Using connectivity to investigate brain (dys)function

Jakub Kopal
CerCo

Vendredi 9 avril 2021 · 9h Visioconférence, Visioconférence

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29 mars 2021

Conférence CerCo

Integration of neural computations performed across distributed brain areas to support visual perception

Lauri Nurminen
Moran Eye Center, University of Utah, USA

Lundi 29 mars 2021 · 16h Visioconférence, Visioconférence

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26 mars 2021

Conférence CerCo

HDR :
Cognition spatiale chez le primate

Jean Baptiste Durand
CerCo

Vendredi 26 mars 2021 · 10h Visioconférence, Visioconférence

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11 janvier 2021

Conférence CerCo

Interplay between dopamine and prefrontal cortex in self-paced decisions

Jérémie Naudé
UPMC, Paris

Lundi 11 janvier 2021 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Daily decisions are often self-generated, motivated by our goals rather than triggered by a stimulus. The neuromodulator dopamine is classically implicated in the learning of stimulus-triggered actions leading to rewards. Dopamine also affects self-paced decisions, probably through its interaction with frontal areas of the cortex. How self-paced decisions emerge from the dynamics of this meso-cortical circuit remains unclear. We addressed this question in a sequential decision task for mice allowing a combination of multi-site electrophysiological recordings, computational modeling and perturbation techniques. In this talk I will show two lines of results : how a distributed sequence of mesocortical activity may be causally linked to decisions, and how dopamine may exert an online regulation of frontal dynamics.
2020 21
21 décembre 2020

Conférence CerCo

PhD Defense :
The role of brain oscillations in visual perception, attention and consciousness

Canhuang Luo
CerCo

Lundi 21 décembre 2020 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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17 novembre 2020

Conférence CerCo

HDR :
Hétérogénéité du vieillissement cognitif :
marqueurs cérébraux anatomiques et fonctionnels

Florence Rémy El Boustani
CerCo

Mardi 17 novembre 2020 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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22 octobre 2020

Séminaire · invité par Andrea Alamia

Jean Michel Hupé
Scientists in the anthropocene: questions raised by doing research on artificial intelligence

Jeudi 22 octobre 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
'This changes everything' wrote Naomi Klein about climate change. Indeed, following the 2015 Paris Agreement (COP21), European countries committed to reach zero net emission of CO2 by 2050. The challenge is tremendous in a world where CO2 emissions never stopped increasing, due to fossil fuels that constitute 80% of energy consumption and is the engine of economic growth. In France, the law requires that every activity, every organization, reduces drastically its carbon footprint. Research should be no exception. The first step to reduce our footprint is to be aware of the impacts of our activities. Some are direct and easy to measure when involving big infrastructures: the CERN is using as much electicity as Madagascar. Others are indirect and could be reduced by changing the way we do research, like flying to attend conferences and visit international colleagues. Yet other consequences are even more indirect and question the very finality of our research. Indeed, scientific research drives innovations that entail structural changes in our society. The climate emergency, as well as the whole ongoing ecological destructions, call for a systematic evaluation of what scientific and technological innovations may bring in terms of ecological consequences. This leads to a taboo question in research: should scientists be considered accountable for the consequences of their discoveries?
We shall discuss together those fundamental questions by taking the example or artificial intelligence (AI) and by questioning how the European Commission frames its expected outcomes and threats in its 2020 White Paper ?On AI?. ?Artificial Intelligence is developing fast. It will change our lives by improving healthcare (e.g. making diagnosis more precise, enabling better prevention of diseases), increasing the efficiency of farming, contributing to climate change mitigation and adaptation, improving the efficiency of production systems through predictive maintenance, increasing the security of Europeans, and in many other ways that we can only begin to imagine. At the same time, Artificial Intelligence (AI) entails a number of potential risks, such as opaque decision-making, gender-based or other kinds of discrimination, intrusion in our private lives or being used for criminal purposes.?
20 octobre 2020

Conférence CerCo

L?insula au travers de l?exploration intracérébrale des épilepsies

Philippe Kahane
Institut des Neurosciences, équipe Synchronisation et modulation des réseaux neuronaux dans l'épilepsie

Mardi 20 octobre 2020 · 13h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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17 septembre 2020

Conférence CerCo

PhD Defense

Mariam Alzaher
Mismatch Negativity a Neural Marker of Spatial Adaptational Plasticity in Unilateral Hearing Loss Patients

Jeudi 17 septembre 2020 · 16h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
This thesis investigates different spatial hearing functions in 3 types of populations: Normal Hearing Subjects (NHS), Unilateral Hearing Loss patients (UHL) and Bilateral Hearing Loss patients(BHL). To discover the mechanisms underlying the adaptive strategies that are observed in UHL with acquired deafness. The main aim of the thesis is to verify whether spatial Mismatch Negativity (MMN) could be a neuronal marker of spatial auditory plasticity observed in UHL patients, and to verify whether these neural correlates are consistent with the spatial auditory performance.
Supervised by Pascal Barone and Mahieu Marx
Jury Members: Anu SHARMA, Aurélie BIDET CAULET, David BAKHOS, Jean luc PUEL.
7 septembre 2020

Séminaire · invité par Emmanuel Barbeau

Opponent iEEG signals from anterior insula vs. ventromesial prefrontal cortex during decision-making tasks

Julien Bastin
Grenoble Institut des Neurosciences

Lundi 7 septembre 2020 · 11AM Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Everybody welcome.
26 juin 2020

Conférence CerCo

Social Physiology for Precision Psychiatry

Guillaume Dumas
Institut Pasteur

Vendredi 26 juin 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
To understand human cognition in its functioning and dysfunctions, it is necessary to combine multiple scales of observation and related disciplines, from the molecular level in genetics to the behavioural level in psychology. In psychiatry, diagnosis, prognostic evaluation and choice of treatment thus require the integration of multiple pieces of information and their temporal evolution, particularly for neurodevelopmental disorders. In this presentation, I will argue that recent advances in integrative neuroscience and computational biology finally provide all the conceptual and methodological tools to encompass these multiple scales and thus develop the necessary social physiology for precision psychiatry. About integrative neuroscience, I will describe how recent efforts in human-human and human-machine interaction have brought more ecological paradigms to the laboratory for the study of human social cognition and its physiological anchoring. Concerning computational biology, I will present how large longitudinal cohorts can achieve the deep genotyping and phenotyping necessary for modern artificial intelligence tools to move beyond the traditional patient-to-control dichotomy to stratification methods or more dimensional models (e.g. RDoC). In conclusion, I will propose ways to integrate these two approaches in computational psychiatry.
18 juin 2020

Conférence CerCo

TBD

Simon Hanslmayr
Univ. Birmingham, UK

Jeudi 18 juin 2020 · TBD Salle de conférence (Pavillon Baudot), Hôpital Purpan

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16 juin 2020

Conférence CerCo

TBA

Thierry Bal Reporté Au Mardi 16 Juin
Institut des Neurosciences Paris-Saclay

Mardi 16 juin 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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10 juin 2020

Conférence CerCo

Soutenance de thèse :
Spatial and temporal integration of binocular disparity in the primate brain

Yseult Héjja-brichard
Cerco

Mercredi 10 juin 2020 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
TBD
9 juin 2020

Conférence CerCo

TBD

Fadila Hadj-bouziane
INSERM U1028, CNRS UMR5292 Lyon Neuroscience Research Center

Mardi 9 juin 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
TBD
14 mai 2020

Conférence CerCo

TBD

Josh Jacobs
Columbia University, New York.

Jeudi 14 mai 2020 · TBD Salle de conférence (Pavillon Baudot), Hôpital Purpan

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12 mai 2020

Conférence CerCo

TBD

Olivier Collignon
UC Louvain

Mardi 12 mai 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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30 mars 2020

Conférence CerCo

Behavioral and neurophysiological mechanisms following motor imagery training

Celia Ruffino
INSERM U1093 Cognition, Action et Plasticité Sensorimotrice

Lundi 30 mars 2020 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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27 mars 2020

Conférence CerCo

Quantifying perinatal brain maturation using anatomical MRI

Guillaume Auzias
Institut des Neurosciences de la Timone (INT)

Vendredi 27 mars 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Perinatal Magnetic Resonance Imaging has proven to be suitable and efficient for detecting alterations in a growing number of pathologies. Major advances in brain MRI acquisition and processing open the way to quantitative analyses not achievable so far. Recent results highlight the great potential of regional descriptors of the geometry of the cortical surface extracted from anatomical MRI to characterize typical and abnormal maturation trajectories in the perinatal period.
24 mars 2020

Conférence CerCo

Brain connectivity:
promises and pitfalls

Jaroslav Hlinka
Institute of Computer Science, Czech Academy of Sciences

Mardi 24 mars 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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2 mars 2020

Conférence CerCo

Executive functions:
underlying neural correlates and approaches for enhancement

Stefanie Enriquez-geppert
University of Groningen

Lundi 2 mars 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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2 mars 2020

Conférence CerCo

Executive functions:
underlying neural correlates and approaches for enhancement

Stefanie Enriquez-geppert
University of Groningen

Lundi 2 mars 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Stefanie works as an Assistant Professor at the Department of Clinical and Developmental Neuropsychology at the University of Groningen, Netherlands. She focuses on translational research on executive functions. Executive functions are regarded especially imperative for success in daily life and their disturbances are related to clinical neuropsychological findings. The scope of her examinations is the specification of neurocognitive processes underlying executive functions (inhibition, conflict monitoring, task switching and memory updating) via EEG and MRI, as well as the development and application of neuroscientific approaches to enhance these functions. In her talk, she will give an overview about these research areas.
27 février 2020

Conférence CerCo

Faces are made of this? Contribution of Orientation and Spatial frequency when processing faces

Valérie Goffaux
UC Louvain

Jeudi 27 février 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Human visual perception results from a complex chain of processes, starting with the spatial frequency- and orientation-selective encoding of luminance in the primary visual cortex (V1). As the visual signals proceed in the visual system, increasingly more complex shape properties are coded, with several high-level regions specializing for selective categories such as faces, words, natural scenes. We know very little about how such high-level specialization builds upon primary encoding stages in V1. Our work combines multiple investigation techniques: psychophysics, electrophysiology (scalp EEG, ERP and steady-state), as well as neuroimaging (of V1 and high-level visual regions) and suggests that the specialization of face processing, though emerging at high-level stages of visual processing, roots into the processing of selective ranges of the primary orientation and SF information. These findings encourage the adoption of more integrative approaches to face perception, and vision in general, encompassing both low- and high-level visual mechanisms.
31 janvier 2020

Conférence CerCo

Algorithm transparency using emerging technologies

Christophe Hurter
ENAC

Vendredi 31 janvier 2020 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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21 janvier 2020

Conférence CerCo

Multi-scale EEG investigation of human temporal lobe sources

Laurent Koessler
CRAN, Nancy

Mardi 21 janvier 2020 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Until a couple of year ago, the contribution of electrical potentials from brain sources to scalp EEG remained unclear and debated among the neuroscience community. Scalp EEG recording is largely used both in medical diagnosis (especially in epilepsy) and in cognition in order to detect and localize brain sources thanks to its non-invasive way of recording, its low cost and its easy way to use. In Nancy, a program of simultaneous multi-scale EEG investigation in human is developed. During this talk, several results will be presented in order to show that the scalp EEG contribution is not as simple and predictive as one might think and that new electrophysiological biomarkers can be find in scalp EEG signals. A special emphasis will be put on temporal lobe investigations because they involve complex networks either in pathology (epilepsy) or in cognition (the visual ventral stream). We demonstrated that mesial temporal sources remain detectable in scalp EEG despite the blurring effect of overlying cortical areas and their deep localizations (Koessler et al., 2005). At the opposite, we demonstrated that basal temporal sources can sometimes escape scalp EEG despite their proximity to the scalp surface and their contribution in fMRI (Jacques et al., 2019).
2019 40
12 décembre 2019

Conférence CerCo

De la compréhension à l'adaptation, l'apport de la psychophysiologie aux handicaps

Réunion De La Société De Psychophysiologie Et Neurosciences Cognitives (spnc)

Jeudi 12 décembre 2019 · 13h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Inscription gratuite mais obligatoire :
https://evento.renater.fr/survey/reunion-de-la-spnc-toulouse-2019-4idq7c0y

Programme préliminaire

DYSTAC-MAP \"Etude neurocognitive de l\'apprentissage procédural et de la mémoire procédurale dans la Dyslexie et le Trouble de l\'Acquisition de la Coordination
Mélanie Jucla Octogone-Lordat et Jessica Tallet Inserm Tonic Toulouse



Couplage perception/action : étude en oculométrie
Quentin Guillon CRNL Lyon

Vers une psychophysiologie sociale: apports de la neuroimagerie en interactions humain-humain et humain-machine
Guillaume Dumas, Inst. Pasteur Paris

Imagerie des états de conscience chez les patients comateux
Stein Silva Inserm Tonic Toulouse

Cortical plasticity and eye diseases: the influence of experience on spatial vision:.
Benoit Cottereau CerCo Toulouse

Déjà -rêvé : un nouveau type de phénomène expérientiel révélé par la stimulation électrique intracérébrale ?
Emmanuel BarbeauCerCo Toulouse

Surdité unilatérale : approches psychoacoustique, qualité de vie et neuroimagerie fonctionnelle par IRMf.
Nicolas Vannson Cerco Toulouse
12 novembre 2019

Conférence CerCo

The alpha predictor of perception

Prof. Gregor Thut
Institute of Neuroscience and Psychology, University of Glasgow, UK

Mardi 12 novembre 2019 · 11h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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21 octobre 2019

Conférence CerCo

Stratégies d'apprentissage et mémoire à long terme d'associations mot-objet chez le jeune enfant et le chien

Danaé Remon
Soutenance de thèse

Lundi 21 octobre 2019 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Nous faisons tous l?expérience de nous souvenirs d?informations ou d?épisodes de vie vécus il y a fort longtemps. Mais qu?en est-il pour nos jeunes enfants et pour les espèces animales éloignées de nous ? Les enfants et les animaux forment-ils également des souvenirs qui peuvent demeurer intacts durant de longues périodes ? Et si tel est le cas, la formation de leurs souvenirs dépend-elle des mêmes règles que celles actuellement établies chez l?Homme adulte ? Cette thèse s?est intéressée à ces questions dans un contexte d?apprentissage associatif bimodal complexe: le concept mot-objet; chez le jeune enfant et le chien domestique. Pour ces deux modèles d?étude, nous avons exploré certains paramètres susceptibles de faciliter l?encodage et le stockage en mémoire de ce type d?information. Nous avons notamment cherché à savoir si le nombre de présentations de nouvelles associations mot-objets lors de l?apprentissage avait un effet sur la rétention du nom de ces objets après un délai, et avons tenté de déterminer le nombre minimal de présentations nécessaire pour induire une trace mnésique. Enfin, nous avons exploré l?efficacité de deux stratégies d?apprentissage sur la mémorisation de nouveaux noms d?objets et démontrons que l?efficacité des stratégies utilisées chez l?Homme évolue au cours du développement de l?enfant et ne semblent pas s?appliquer aux chiens. En bref, nos résultats apportent des éclaircissements quant à certains principes qui sous-tendent la formation de mémoires sensorielles chez un organisme en développement ainsi que chez une espèce animale non primate, et nous permettent d?émettre des hypothèses quant aux mécanismes cérébraux sous-jacents.
14 octobre 2019

Séminaire · invité par Benoit Cottereau

Fixational eye movements:
Where are we now? Which implications for vision scientists? / A low-vision assistive device using mixed reality and spatial frequency enhancement to facilitate face recognition

Josselin Gautier
UC Berkeley

Lundi 14 octobre 2019 · 11h Salle de réunion 3eme (Pavillon Baudot), Hôpital Purpan

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Résumé
As we scan a scene by moving our eyes, most visual information -especially the fine detail- is acquired during fixational pauses. Even during these fixations, the eyes are never completely still and follow specific and partially controlled movements composed mainly of microsaccades and drifts. In the last decade, mechanisms responsible for the generation of microsaccades and its spatio-temporal consequences in decorrelating the content have been proposed. I will present our studies showing that microsaccades highlight others important joint mechanisms for binocular vision in the accommodation and vergence systems. I will detail an ongoing project aiming at relying on these eye movements to define spatially and temporally two characteristical points on the retina: the Preferred Retinal Locus of Fixation (PRL) and the Peak Cone Density. While acuity appears relatively uniform around a neighborhood, can it first explain in a functional manner the anchoring of PRL in the healthy subjects? An oculomotor definition of the PRL would allow to monitor its development in patients with Central Vision Loss (CVL) such as Age-related Macular Degeneration (AMD). Such a method could in turn highlight the binocular functions involved in Binocular Central Vision Loss and guide new approaches to visual rehabilitation for these individuals. In a second part, a more applied development for these people with CVL (AMD) will be described. A low-vision assistive device aiming at facilitating face recognition through local enhancement and mixed reality was proposed and evaluated on few patients. Preliminary positive results provide important insight on the design, methods and techniques that might one day be implemented in see-though glasses.
27 septembre 2019

Conférence CerCo

Big data EEG, the next frontier

Arnaud Delorme, Dr Cnrs
CerCo

Vendredi 27 septembre 2019 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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25 septembre 2019

Séminaire · invité par Isabelle Berry

"Distance entre distributions :
application à l'Imagerie Médicale et à l'Aéronautique"

Sana Rebbah
thèse en avant-première

Mercredi 25 septembre 2019 · 10h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
\"Dans le domaine médical, au cours des deux dernières décennies, un nombre croissant de méthodes d?analyse d?images quantitatives ont été développées dont l\'analyse par régions d\'intérêt, l\'analyse voxels à voxels et l\'analyse d\'histogrammes. Cette dernière est largement utilisée dans la cadre de la recherche sur la sclérose en plaques afin de quantifier les changements pathologiques diffus particulièrement présents dans cette maladie. Un inconvénient de cette approche est que l?ensemble des informations incluses dans l?histogramme n?est pas exploité ; seules des mesures arbitraires sont choisies pour décrire l?histogramme ; incluant la moyenne, la médiane, les quantiles... Ainsi dans un premier lieu, nous avons proposé d\'intégrer dans un classifieur toute l\'information incluse dans l\'histogramme et non pas seulement quelques descripteurs locaux, dans le but d\'améliorer les performances de classification des populations de sclérose en plaques (groupes dans un essai thérapeutique et in fine groupes de pronostics différents). Par la suite, étant donné que l\'histogramme est une estimation trop simpliste d\'une distribution de probabilité, nous présentons l\'une des applications possibles de la géométrie de l\'information sur les distributions de probabilité et démontrons l\'intérêt de l?utilisation de la géométrie non-euclidienne dans le contexte de la classification des populations de la maladie d\'Alzheimer.
Nous avons notamment fait l\'analogie avec le domaine de l\'aéronautique, plus précisément dans l\'étude des retards aéroportuaires. En effet, l?analyse actuellement réalisée se situe au niveau macroscopique et fournit un indicateur de retard moyen, sans tenir compte des mécanismes intermédiaires pouvant conduire au retard final. Ainsi, dans le cadre de la classification des retards aéroportuaires, tout comme dans les applications médicales, nous avons remplacé l\'indicateur moyen par un modèle statistique paramétrique plus complet : les distributions de probabilité.\"
11 juillet 2019

Conférence CerCo

Neural entrainment influences perceived speech content

Anne Kösem
Lyon Neuroscience Research Center (CNRL)

Jeudi 11 juillet 2019 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
While neural oscillations are known to entrain to the dynamics of speech, it is debated whether this entrainment supports the neural mechanism involved in speech processing. I will first discuss evidence that entrained oscillations build temporal predictions about the duration of speech tokens that affect perception. I will also present recent results suggesting that neural entrainment can also be a marker of speech-specific processes. In this multi-talker study, neural entrainment to a target speech diminishes in the presence of an intelligible distractor, suggesting that entrainment here reflects disrupted linguistic processing of attended speech due to competition.
25 juin 2019

Conférence CerCo

Ultrasounds to study the brain of non-human primates

Pierre Pouget
CNRS - ICM (Paris)

Mardi 25 juin 2019 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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21 juin 2019

Séminaire · invité par Muriel Mescam

Expression-based human induced pluripotent stem cell-derived cardiomyocyte models of electrophysiology

Brian Carlson
University of Michigan - Department of Molecular and Integrative Physiology

Vendredi 21 juin 2019 · 11h Salle de réunion 2eme (Pavillon Baudot), Hôpital Purpan

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Résumé
In this talk I will first present how the function of individual ion channels are linked together to form a computational model of cardiomyocyte electrophysiology (or any other self excitable cell such as a neuron). Then I will discuss how we are using this fundamental formulation to build an expression-based model of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) that can be used as a theoretical platform to understand how cardiomyocytes might respond to possible proarrhythmic drugs.
20 juin 2019

Conférence CerCo

Information geometry highlight scientific synergies between statistics and geometry

Stéphane Puechmorel
Laboratoire de recherche ENAC - Présentation comme chercheur associé au CerCo

Jeudi 20 juin 2019 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The dynamics of this combination is driven by many applications in the field of signal processing (radar, images, ?) , massive data (internet databases, monitoring, ?) and artificial intelligence (machine learning, neural networks ...). While traditional statistics deals mainly with models based on sets of probability laws, parameterized or not, information geometry allows an extra level of description by adding a differential, metric structure. Within this frame, it becomes possible to derive distances between probability densities, to compute Fréchet means and to find best approximations on submanifolds, which is the usual setting for problems with hidden variables. In machine learning, it allows to improve over standard stochastic gradient algorithms by using the metric information. Furthermore, when dealing with complex systems with symmetries, using geometric considerations reduces the dimension of the problem, thus simplifying the learning process. The talk will be divided into two parts:

-> From statistical models to statistical manifolds and back. Important tools coming from geometry will be introduced, with some simple examples. The notion of dual connections, that is the most basic concept in information geometry will be explained in an intuitive manner and a recent result allowing concrete realizations of statistical manifolds as densities families will be briefly stated. Finally, the extension to infinite dimensional geometry, which is an active area of research in our team, will be sketched.
-> A medical imaging application. Some recent results relating information geometry to standard biomarkers in neuroimaging will be detailed. This is an ongoing work, with surprising ramifications in the air traffic management, that has already given promising results.
20 juin 2019

Conférence CerCo

Information geometry highlight scientific synergies between statistics and geometry

Florence Nicol
Laboratoire de recherche ENAC - Présentation comme chercheur associé au CerCo

Jeudi 20 juin 2019 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The dynamics of this combination is driven by many applications in the field of signal processing (radar, images, ?) , massive data (internet databases, monitoring, ?) and artificial intelligence (machine learning, neural networks ...). While traditional statistics deals mainly with models based on sets of probability laws, parameterized or not, information geometry allows an extra level of description by adding a differential, metric structure. Within this frame, it becomes possible to derive distances between probability densities, to compute Fréchet means and to find best approximations on submanifolds, which is the usual setting for problems with hidden variables. In machine learning, it allows to improve over standard stochastic gradient algorithms by using the metric information. Furthermore, when dealing with complex systems with symmetries, using geometric considerations reduces the dimension of the problem, thus simplifying the learning process. The talk will be divided into two parts:
-> From statistical models to statistical manifolds and back. Important tools coming from geometry will be introduced, with some simple examples. The notion of dual connections, that is the most basic concept in information geometry will be explained in an intuitive manner and a recent result allowing concrete realizations of statistical manifolds as densities families will be briefly stated. Finally, the extension to infinite dimensional geometry, which is an active area of research in our team, will be sketched.
-> A medical imaging application. Some recent results relating information geometry to standard biomarkers in neuroimaging will be detailed. This is an ongoing work, with surprising ramifications in the air traffic management, that has already given promising results.
20 juin 2019

Conférence CerCo

Pierre Marechal
Institut de Mathématiques de Toulouse -Présentation comme chercheur associé au CerCo

Jeudi 20 juin 2019 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
We derive an entropy model for diffusion MRI and show that Fenchel duality techniques
make this model tractable. This generalizes a model proposed by Daniel Alexander in 2005, in
which the displacement of particles is confined to a sphere. In order to better suit the physics of the
diffusion process, we propose to relax this constraint. The Kullback-Leibler relative entropy is used
to measure the discrepancy between the probability to be inferred and some reference measure. The
obtained optimization problem is then studied using tools from partially finite convex programming.
17 juin 2019

Conférence CerCo

Scott Makeig, Cyril Pernet, Arnaud Delorme, Robert Oostenveld Et Leila Reddy
Brain Imaging Data Structure

Lundi 17 juin 2019 · 13h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Symposium de 2 heures et demi sur BIDS (Brain Imaging Data Structure) avec les intervenants Scott Makeig, Cyril Pernet, Arnaud Delorme, Robert Oostenveld et Leila Reddy
14 juin 2019

Conférence CerCo

Soutenance d' HDR :
'Vision Spatiale chez le Primate :
une Approche Interdisciplinaire'

Benoit Cottereau
Cerco CNRS UMR 5549

Vendredi 14 juin 2019 · 13h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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13 juin 2019

Conférence CerCo

Motion integration and segmentation:
what needs to be put together (or not) ?

Guillaume Masson
Institut des Neurosciences de la Timone (INT)

Jeudi 13 juin 2019 · 16h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
To estimate the direction and speed of a moving object, the motion processing pathways must solve two conflicting constraints called motion integration and motion segmentation. Recent empirical and computational evidences have challenged the classical two-stage models where a V1-MT cascade first sense local motion signals and second integrate them. I will briefly review some of them to propose that ones must consider simultaneous the interactions between spatiotemporal frequencies and motion direction/speed channels to solve the integration/segmentation problem.
13 juin 2019

Conférence CerCo

Impact of Healthy Aging on Visuo-Spatial Cognition

Angelo Arleo
Institut de la Vision

Jeudi 13 juin 2019 · 15h20 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Ageing leads to gradual changes in the imaging structures of the eye, sensory transduction, neural transmission, and perceptual functions. Age-related cognitive and executive alterations are overlaid on visual perception, as demonstrated through divided-attention and spatial navigation tasks. We study how ageing impacts spatial cognition in ecological-like conditions, which allow daily life situations to be reproduced in controlled experiments. We focus on eye movements mediating active exploration of the environment, which is relevant to the construction of spatial representations and to wayfinding behaviour. Probing age-related effects on spatial cognition can shed light on autonomy loss markers pertinent to the way older adults interact with the world through active visual sensing and goal-oriented navigation. First, this talk will introduce the French cohort study SilverSight, which was launched in 2014 to assess, both cross-sectionally and longitudinally, anatomic and functional changes induced by visual ageing. The goal is understand the relations between retinal cellular changes (e.g., structural modifications measured with high-resolution retina imaging) and visual symptoms, in order to identify functional biomarkers of physiological vs. pathological ageing. Second, this talk will focus on age-related changes in spatial learning during a series of navigation tasks. These changes have been previously characterised in terms of deficits in the use of allocentric strategies in older adults. However, an alternative hypothesis is that navigation difficulties in aged people are associated with visuospatial cue processing rather than with strategic choices per se. We tested this hypothesis by having young and older participants (n=40) navigating a real, ecological environment. Our findings show that older adults reorient preferentially according to geometric cues, whereas young adults preferentially use landmarks. Recordings of both body and eye movements as subjects reoriented in space allowed us to identify specific motion signatures associated with either landmark or geometric spatial coding. In particular, gaze dynamics were predictive of single-subject-single-trial spatial cue preference. Given the extensive use of landmarks during spatial navigation paradigms, these results challenge the traditional view of a specific deficit for allocentric learning in ageing. In addition, these results extend previous findings on geometric cue preference in children and therefore suggest an inverted U-profile of landmark processing across lifespan. We further tested this hypothesis by having children, young, and older adults (n=79) navigating a Y-maze in which we controlled the presence of landmarks and geometric cues. Our results show that, when landmarks are the only available cues, children and older adults are impaired in performing allocentric navigation (expectedly). However, our findings show that when geometric cues are provided by the maze, then both children and older adults become as efficient as young adults in using allocentric strategies. Overall, these results highlight the need for reframing the classical allocentric/egocentric dichotomy with respect to age. They suggest that the so far observed deficiencies of allocentric processing in ageing can result from landmark coding impairments and they predict the recovery of allocentric spatial learning in geometrically polarised environments.
13 juin 2019

Conférence CerCo

Ideal and super-ideal confidence observers

Pascal Mamassian
Laboratoire des Systèmes Perceptifs (Ecole Normale Supérieure)

Jeudi 13 juin 2019 · 14h40 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Visual confidence refers to our ability to predict the correctness of our perceptual decisions. Knowing the limits of this ability, both in terms of biases (e.g. overconfidence) and sensitivity (e.g. blindsight), is clearly important to approach a full picture of perceptual decision making. The measurement of visual confidence with the classical method of confidence ratings presents both advantages and disadvantages. In recent years, we have explored an alternative paradigm based on confidence forced-choice. In this paradigm, observers have to choose which of two perceptual decisions is more likely to be correct. I will review some behavioural results obtained with the confidence forced-choice paradigm. I will also present two ideal observers based on signal detection theory, one that uses the same information for perceptual and confidence decisions, and another one that has access to additional information for confidence. These ideal observers help us quantify the limitations of human confidence estimation.
13 juin 2019

Conférence CerCo

Exploring the processing of spatial frequencies in people with retinal diseases for understanding scene perception

Carole Peyrin
Laboratoire de Psychologie et NeuroCognition (LPNC)

Jeudi 13 juin 2019 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Theories on visual perception agree that scenes are processed in terms of spatial frequencies. Low spatial frequencies (LSF) carry coarse information whereas high spatial frequencies (HSF) carry fine details of the scene. However, how and where spatial frequencies are processed within the brain remain unresolved questions. Along with neuroimaging studies on healthy subjects, patients with retinal disorders constitute pathological models which enable the specific investigation of the role of spatial frequencies during scene perception through the relationship between the location of the lesion on the retina and the processing of spatial frequencies, but also the respective role of central and peripheral vision. We specifically explored the relationship between central retinal damage (age-related macular degeneration), peripheral retinal damage (glaucoma) and the processing of spatial frequencies during scene categorization.
7 juin 2019

Conférence CerCo

Brain-Computer Interfaces:
Learning how to use them, Using them to learn

Camille Jeunet
CLLE Lab, Université Toulouse 2 & CNRS

Vendredi 7 juin 2019 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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5 juin 2019

Conférence CerCo

Taking cognitive testing into the wild to observe cognitive evolution in action

Maxime Cauchoix
IAST & SETE (UT3-CNRS)

Mercredi 5 juin 2019 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
During the last century, comparative cognition and neurosciences have improved our understanding of animal minds while evolutionary ecology has revealed how selection acts on traits through evolutionary time. In this talk, I will describe how cognition can be subject to natural selection like any other biological trait and thus can be studied with evolutionary ecology tools.
In particular, I will emphasis on how:
(1) considering individual differences in cognitive performance
(2) the development of new technologies to measure cognitive abilities in wild animals,
(3) documenting socio-ecological causes and fitness consequences of individual differences
can help us to understand better the evolution of animal cognition.
28 mai 2019

Séminaire · invité par Leila Reddy

Jonathan Curot
Exploring long-term memory and neuronal dynamics in epileptic patients with electrical brain stimulation

Mardi 28 mai 2019 · 10h30 Salle de réunion 2eme (Pavillon Baudot), Hôpital Purpan

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28 mai 2019

Séminaire · invité par Leila Reddy

Ce que peut nous apprendre le syndrome de l?amygdale élargie

Marie Denuelle
CHU Purpan

Mardi 28 mai 2019 · 10h30 Salle de réunion 2eme (Pavillon Baudot), Hôpital Purpan

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22 mai 2019

Conférence CerCo

The role of the hippocampus in recognition memory

Chris Bird
University of Sussex, UK

Mercredi 22 mai 2019 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Declarative memory is the ability to remember or recognize events and facts that we have experienced or learnt in the past. While the hippocampus is known to play a critical role in some declarative memory processes, its specific contribution to recognition memory remains controversial. For example, some studies of humans with hippocampal damage suggest that all declarative memory processes are impaired, whereas other studies in humans and non-human primates indicate the hippocampus is only involved in the recollection of memories. I will argue that the main processing role of the hippocampus is to bind items and spatial / contextual information together and this explains its pervasive role in declarative memory. The recognition of unfamiliar faces represents a rare situation where recognition memory is not dependent on the hippocampus, and it is analogous to tasks in non-human primates that use unfamiliar objects. However, recognition memory supported by regions outside of the hippocampus is inadequate for everyday declarative memory function.
22 mai 2019

Conférence CerCo

Familiarity and recollection in normal and pathological aging:
Studies on underlying mechanisms and neural correlates

Christine Bastin
GIGA-Cyclotron Research Center in vivo imaging University of Liège, Belgium

Mercredi 22 mai 2019 · 10h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
A decreased capacity to remember past events is observed in healthy aging and is the hallmark of Alzheimer?s disease. Cognitive neuroscience research explores the nature of the memory processes that are more specifically affected in normal and pathological aging. Notably, the distinction between recollection (i.e., recall of the encoding context of past events) and familiarity (i.e., judgments of oldness) has allowed to clarify the picture by showing dissociation between these two processes in healthy aging. In the course of Alzheimer?s disease, however, evidence for a dissociation between recollection and familiarity is mixed. Our work aims at understanding the neurocognitive architecture of recollection and familiarity by examining how these processes are modulated during aging and Alzheimer?s disease. Our research includes studies on variables that allow older people to reliably use familiarity to support memory decisions, studies on the source of subjective memory judgments in aging, and factors that may affect familiarity-based recognition memory in early Alzheimer?s disease.
21 mai 2019

Conférence CerCo

Soutenance de thèse (in English) Prior knowledge contribution to declarative learning. A study in amnesia, aging and Alzheimer?s disease

Pierre-yves Jonin
Cerco (UMR5549) & Empenn (UMR6074)

Mardi 21 mai 2019 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The study of human memory has had two historic moments in the last sixty years. 1957
marks the discovery of the role of the medial temporal lobes in conscious or "declarative"
learning. 1997 marks the discovery of two systems of declarative memory, episodic and
semantic memories. Clinical case studies in neuropsychology were critical to these
discoveries, and the present work follows on from this tradition.
We demonstrate the existence of a rapid learning process independent of the
hippocampal system, which can facilitate memorization in amnesia and in aging, but is
selectively impaired in Alzheimer's disease. The perirhinal cortex seems to be at the heart
of this learning process.
Our results highlight the dynamic nature of declarative learning and the entanglement
between "knowing" and "remembering". This thesis offers multiple perspectives to
understand memory deficits in neurological patients, and for the diagnosis of Alzheimer's
disease. Finally, it contributes to the comprehension of learning factors, with potential
applications in the educational field.
23 avril 2019

Conférence CerCo

Soutenance de thèse :
Validation d'une nouvelle électrode hybride intracérébrale comportant des tétrodes dans l'épilepsie pharmaco-résistante

Elodie Despouy
CerCo

Mardi 23 avril 2019 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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16 avril 2019

Conférence CerCo

Reconstructing Faces from fMRI Patterns using Deep Generative Neural Networks

Leila Reddy
CerCo

Mardi 16 avril 2019 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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16 avril 2019

Conférence CerCo

Dynamics of electrophysiological responses to face, gaze and emotion in the human occipito-temporal cortex

Nathalie George
ICM Paris

Mardi 16 avril 2019 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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16 avril 2019

Conférence CerCo

On the linkage between Face Processing, Language Processing and Narrowing during Development

Olivier Pascalis
LNPC Grenoble

Mardi 16 avril 2019 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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16 avril 2019

Conférence CerCo

The strategic display of emotions

Astrid Hopfensiz
IAST Toulouse

Mardi 16 avril 2019 · 9h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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15 avril 2019

Conférence CerCo

Soutenance de thèse :
Traitement des signaux de communication dans le syndrome de Prader-Willi :
aspects descriptifs, analytiques et évolutifs

Jimmy Debladis
CerCo

Lundi 15 avril 2019 · 13h45 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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26 mars 2019

Conférence CerCo

Soutenance d'HDR

Robin Baurès
CerCo

Mardi 26 mars 2019 · 9h30 PPR salle 4, Hôpital Purpan

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Résumé
*************
Due to the flooding of the conference room, the HDR will be in PPR, room 4. The place is limited, please let me know if you intend to come so I can get an estimation of the number.

Robin
*************



Perception du temps avant contact : Bilan et perspectives

Dans cette soutenance d'HDR, je présenterai les travaux menés sur la perception du temps avant contact, c'est-à-dire la capacité qu?a un observateur à déterminer le moment d?arrivée d?un objet. En particulier, j?exposerai mes travaux portant sur la capacité à réaliser une double estimation, si deux objets sont à estimer en même temps, et le rôle de l?attention dans le processus d?estimation.
La soutenance me permettra aussi de présenter mes projets en cours, sur une double approche. En chirurgie éveillée tout d?abord, nous cherchons à déterminer l?implication des aires cérébrales sensori-motrices dans le cas d?une estimation d?un objet sur une trajectoire de collision avec l?observateur. Dans un domaine connexe, nous cherchons à faire apprendre à un réseau de neurones artificiels bio-inspiré à anticiper une trajectoire de balle, tel que peut le faire un expert sur le terrain sportif, afin de mieux modéliser l?apprentissage perceptif.
25 mars 2019

Conférence CerCo

Conférence Pré-HDR

Benoit Bardy / Reinoud Bootsma / Jenny Coull / Laurent Perrinet
Euromov, Montpellier / ISM, Marseille / LNC, Marseille / INT, Marseille

Lundi 25 mars 2019 · 14h , Hôpital Purpan

Affiche
Résumé
*************
Due to the flooding of the conference room, the pre HDR conference will be in PPR, room 4. The place is limited, please let me know if you intend to come so I can get an estimation of the number.

Robin (robin.baures@cnrs.fr)
*************


Benoit Bardy
What your moves say about you: Action-perception dynamics, human synchronization and mental health

Reinoud Boostma
Information d'ordre fractionnaire dans le contrôle du mouvement ?

Jenny Coull
How does the human brain predict time?

Laurent Perrinet
From the retina to action: Predictive processing in the visual system

(I do not have enough space to copy all the abstracts, send me an email if you are willing to know more)
25 mars 2019

Conférence CerCo

Predicting time in the human brain

Jennifer Coull
LNC - Aix-Marseille Université

Lundi 25 mars 2019 · 14h Salle 4, Hôpital Purpan

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Résumé
Being able to predict when relevant events are likely to occur improves how quickly and accurately they are processed. Using fMRI, we have found that left inferior parietal cortex mediates motor and perceptual benefits of temporal predictability. This region is engaged whenever learned temporal cues induce expectations about the time at which a subsequent target will appear. More specifically, it?s activated at the cue, rather than target, stage of the task, indicating its involvement in accessing a stored temporal template of the expected time (the ?prior?) before the target actually appears. Even in the absence of temporal cues, the elapse of time itself can provide predictive information about target onset time (the ?hazard function?), honing performance dynamically across time. fMRI data indicate that activity in right prefrontal cortex, as well as left inferior parietal cortex, tracks the way in which temporal expectations evolve as a function of elapsing time. These data highlight the distinct functional mechanisms needed to implement fixed versus dynamic forms of temporal prediction.

****
Due to a request and for visibility, I am splitting the mini conference announce in 4 different announces, this is however the same event in line with my HDR defense.

Robin

****
25 mars 2019

Conférence CerCo

What your moves say about you:
Action-perception dynamics, human synchronization and mental health

Benoit Bardy
EuroMov, Univ. Montpellier

Lundi 25 mars 2019 · 14h Salle 4, Hôpital Purpan

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Résumé
In this presentation, we will emphasize the informational nature of human synchronization, together with its consequences for the understanding of how the way we move reveals who we are. The notion of Individual Motor Signature (IMS) will be presented, reducing to one low-dimensional variable the interaction of multiple degrees of freedom at various levels of the human body (Slowinski et al., 2016). A novel way to evaluate how these signatures are influenced, when interacting in a dyad or in a group (Alderisio et al., 2017), by physical and movement similarity, social competences and mental deficits, will be introduced. We will present a recently developed digital architecture that modulates IMS in real-time during social interaction with artificial agents (avatars and robots), and we will show how this architecture can be used for the rehabilitation of patients suffering from mental and social disorders (Slowinski et al., 2017), as well as for the understanding of how group synchronization emerges in natural situations.


References
Alderisio, F., G. Fiore, Salesse, R., Bardy, B. G., & di Bernardo, M. (2017). Interaction patterns and individual dynamics shape the way we move in synchrony. Scientific Reports, 6846.

S?owi?ski, P., Zhai, C., Alderisio, F., Salesse, R., Gueugnon, M., Marin, L., Bardy, B. G., di Bernardo, M., & Tsaneva-Atanasova, K. (2016). Dynamic similarity promotes interpersonal coordination in joint-action. Journal of the Royal Society Interface, 13: 20151093.

S?owi?ski, P., Zhai, C., Alderisio, F., Shen, Y., Tino, P., Bortolon, C., Burca, M., Raffard, S., Capdevielle, D., Cohen, L., Khoramshahi, M., Billard, A., Salesse, R., Gueugnon, M., Marin, L., Bardy, B. G., di Bernardo, M., Tsaneva-Atanasova, K. (2017). Kinematic biomarkers of schizophrenia. Npj Schizophrenia, 3:8

Acknowledgements. This work was funded by the European Project AlterEgo FP7 ICT 2.9 - Cognitive Sciences and Robotics, Grant Number 600610 (www.euromov.eu/alterego).

****
Due to a request and for visibility, I am splitting the mini conference announce in 4 different announces, this is however the same event in line with my HDR defense.

Robin

****
25 mars 2019

Conférence CerCo

From the retina to action:
Predictive processing in the visual system

Laurent Perrinet
Institut de Neurosciences de la Timone

Lundi 25 mars 2019 · 14h Salle 4, Hôpital Purpan

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Résumé
Visual areas are essential in transforming the raw luminous signal into a representation which efficiently conveys information about the environment. This process is constrained by various factors such as a wide variety of changes in the characteristics of the visual image but also by the necessity to be able to respond as quickly as possible to the incoming sensory stream, for instance to drive a movement of the eyes to the location of a potential danger. To achieve this, it is believed that the visual system takes advantage of the existence of a priori knowledge in the structure of visual information, such as the regularity in the shape and motion of visual objects. As such, the predictive coding coding framework offers a unified theory to explain many of the mechanisms at the different levels of the visual system and which were unveiled by decades of study in neurophysiology and psychophysics.

****
Due to a request and for visibility, I am splitting the mini conference announce in 4 different announces, this is however the same event in line with my HDR defense.

Robin

****
25 mars 2019

Conférence CerCo

Information d'ordre fractionnaire dans le contrôle du mouvement ?

Reinoud Bootsma
Institut des Sciences du Mouvement UMR 7287

Lundi 25 mars 2019 · 14h Salle 4, Hôpital Purpan

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Résumé
En tant qu'exemples paradigmatiques de nos interactions comportementales avec des éléments dynamiques de l'environnement, les actions d'interception offrent une riche fenêtre sur les mécanismes perceptuomoteurs sous-jacents au comportement. Comme la plupart de nos actions quotidiennes, l'interception locomotrice est contrôlée prospectivement. Toutefois, la nature de l'information utilisée et la manière dont elle est intégrée dans le mouvement font encore l'objet de nombreux débats. Je présenterai des travaux expérimentaux indiquant que, selon les contraintes de la tâche, l'interception locomotrice semble dépendre des combinaisons de la position de l'angle de relèvement, de la vitesse et/ou de l'accélération. Je suggérerai qu'au lieu d'être limités aux dérivés temporels d'ordre entier (classiques), les systèmes biologiques pourraient intégrer d?information d'ordre fractionnaire dans la dynamique d'attraction sous-jacente.

****
Due to a request and for visibility, I am splitting the mini conference announce in 4 different announces, this is however the same event in line with my HDR defense.

Robin

****
25 mars 2019

Conférence CerCo

Conférence Pré-HDR

Benoit Bardy / Reinoud Bootsma / Jenny Coull / Laurent Perrinet
Euromov, Montpellier / ISM, Marseille / LNC, Marseille / INT, Marseille

Lundi 25 mars 2019 · 14h , Hôpital Purpan

Affiche
Résumé
*************
Due to the flooding of the conference room, the pre HDR conference will be in PPR, room 4. The place is limited, please let me know if you intend to come so I can get an estimation of the number.

Robin (robin.baures@cnrs.fr)
*************


Benoit Bardy
What your moves say about you: Action-perception dynamics, human synchronization and mental health

Reinoud Boostma
Information d\\\'ordre fractionnaire dans le contrôle du mouvement ?

Jenny Coull
How does the human brain predict time?

Laurent Perrinet
From the retina to action: Predictive processing in the visual system

(I do not have enough space to copy all the abstracts, send me an email if you are willing to know more)
14 février 2019

Conférence CerCo

De la pathologie à la réhabilitation :
deux exemples de prise en charge de pathologies rétiniennes

Vincent Soler
Centre de la Rétine, CHU Purpan

Jeudi 14 février 2019 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Nous aborderons dans l?exposé deux types de pathologies rétiniennes : les maculopathies et les décollements de rétine. En préambule, un petit rappel? Si l??il est comparé à un appareil photographique classique, la rétine en est la pellicule.

La macula correspond à la partie centrale de la rétine. Les maculopathies sont à l?origine d?une perte de la vision centrale : reconnaissance des visages et lecture sont ainsi deux fonctions grandement affectées. La maculopathie la plus fréquente est la dégénérescence maculaire liée à l?âge. Dans cette maladie, la rétine située autour de la macula, quoique moins sensible aux stimulations visuelles que la macula, reste fonctionnelle. Ainsi, la rétine périmaculaire peut dans une certaine mesure prendre le relais de la macula si tant est que l?on parvient à stabiliser la fixation (qui sera dite excentrique) par une zone de rétine périmaculaire (PRL pour Preferred Retinal Locus). Le but de l?apprentissage perceptif est ainsi une méthode qui permet d?améliorer les fonctions visuelles chez les patients atteints de maculopathies en stimulant la fixation excentrique. Nous développerons les résultats obtenus par apprentissage perceptif chez des patients atteints de maculopathie.

Le décollement de rétine classique (dit rhegmatogène) est caractérisé par la séparation de la rétine de son support fonctionnel et le traitement est chirurgical. La chirurgie la plus pratiquée est la vitrectomie. La vitrectomie permet la mise en place dans la cavité oculaire (vitréenne plus précisément) d?une bulle de gaz ou d?huile de silicone qui remplit la cavité et qui a pour fonction de maintenir la rétine réappliquée, de la même façon qu?une broche orthopédique stabilise un os cassé le temps que le cal osseux se consolide. Nous présenterons les résultats expérimentaux concernant l?étude de l?efficacité et de l?innocuité d?un nouveau produit de tamponnement interne basé sur les triglycérides à chaines moyennes (différent des gaz ou des huiles de silicone utilisés jusqu?ici).
24 janvier 2019

Conférence CerCo

Ten claims about the extrastriate symmetry network

Alexis Makin
University of Liverpool

Jeudi 24 janvier 2019 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
We can make ten claims about the symmetry perception, and rank-order them from highly plausible to moderately plausible. Claim 1) people and animals like visual symmetry, and use symmetry in mate choice. However, preference for symmetry in abstract patterns might be independent from attraction to symmetrical faces. Claim 2) There is a network of symmetry-sensitive brain areas in the extrastriate cortex. The primary and secondary visual cortices are not sensitive to symmetry. Converging evidence comes from comes from fMRI, TMS and EEG work. Claim 3) The extrastriate network responds to symmetry automatically, even when people are not attending to it. Claim 4) The amplitude of the symmetry response scales with the perceptual goodness (i.e. strength or salience) of different regularities. Claim 5) The network always responds to symmetry in the image. Sometimes it can go beyond this, and recover symmetry in the object. Claim 6) The network can code symmetry independently in each hemisphere. Claim 7) The network responds to both symmetry and anti-symmetry, but the response to symmetry is often stronger. Claim 8) The network is indifferent to colour of the elements. Claim 9) The network can integrate pattern information presented at different points in time. Claim 10) The dorsal stream drives spatial attention along the axis of reflection. I conclude that symmetry is useful for understanding the properties of mid-level vision, where consciously perceived structure emerges.
2018 20
21 décembre 2018

Conférence CerCo

Soutenance de thèse :
Une exploration des phénomènes expérientiels mnésiques :
de la sémiologie à l'activité neuronale unitaire.

Jonathan Curot
CerCo

Vendredi 21 décembre 2018 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
En 2008, l?équipe canadienne d?A. Lozano induit « par hasard » un souvenir de jeunesse chez un patient obèse par une stimulation électrique intracérébrale (SEIC) de l?hypothalamus et du fornix dans le but de le faire maigrir. Sur le poids, ce sera un échec, mais l?activation de la mémoire à long terme par une telle stimulation poussera cette équipe à développer la même technique pour activer les réseaux mnésiques dans un but thérapeutique dans la maladie d?Alzheimer. En 2018, leurs résultats sont enfin publiés. Ils sont décevants. En parallèle, depuis 10 ans, se multiplient les protocoles de SEIC pour tenter d?augmenter les performances mnésiques humaines, mais avec des résultats contradictoires ou faibles.
L?exemple précédent est démonstratif de l?importance des phénomènes expérientiels, du déjà-vu aux réminiscences plus complexes, qu?ils soient induits par une SEIC ou spontanés, comme source d?inspiration pour moduler la mémoire à long terme. Mais il est également illustratif des carences de la neuromodulation électrique : une méconnaissance des effets neuronaux de la SEIC, une absence de consensus sur les paramètres de stimulation, dans un contexte où les réseaux de la mémoire à long terme ne sont que partiellement connus.

Par cette thèse, nous proposons d?explorer ces phénomènes expérientiels, insuffisamment exploités, au travers de 6 études et sous deux dimensions, pour tenter de mieux comprendre comment activer les réseaux mnésiques :
- une dimension phénomènologique avec une analyse détaillée du contenu de ces phénomènes, dans la littérature, dans notre base de données française et par le cas clinique d?une patiente épileptique atypique, en les confrontant aux classifications contemporaines de la mémoire déclarative.
- une dimension électrophysiologique avec une analyse des effets des SEIC sur les réseaux mnésiques à différentes échelles.

Nous démontrons que la mémoire est activable de manière prédictible par les SEIC qui semblent reproduire des patterns normaux de la cognition. Reste à déterminer les paramètres optimaux, électriques notamment, pour l?activer de façon reproductible. Nous rapportons dans ce cadre les résultats préliminaires de l?impact de la fréquence de SEIC, en particulier sur l?activité neuronale unitaire, ce qui n?a encore jamais été fait in vivo chez l?homme.
12 décembre 2018

Séminaire · invité par Alexandra Séverac

Extending Electrical Vestibular Stimulation from basic science to clinical use

Raymond Reynolds
School of Sport, Exercise & Rehabilitation Sciences University of Birmingham, UK

Mercredi 12 décembre 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Electrical Vestibular Stimulation is a simple method for stimulating the vestibular system and evoking sensations of movement. It has predominantly been used as a basic research tool, typically for studying postural control during standing or walking. However, it has long been observed that patients with vestibular loss exhibit altered responses to GVS, suggesting diagnostic potential. However, progression to clinic has been slow. This is largely due to practical issues, but also limitations of our knowledge regarding the stimulus mechanism. Here I will present some recent studies using non-invasive assessment of the EVS-evoked vestibular-ocular reflex in healthy persons, as well as patients with Vestibular Schwannoma and complete unilateral vestibular loss. These studies show that EVS compares well to established tests (e.g. caloric irrigation) in terms of diagnostic capability, while offering greater convenience and practicality. Nevertheless, there remain significant questions regarding precisely which pathologies to which this technique can be applied. These questions will be answered by a combination of further empirical observations in vestibular patients, along with a better understanding of the basic stimulus mechanism.
23 novembre 2018

Conférence CerCo

Human reconstruction of sensory signals from natural scenes

Peter Neri
Laboratoire des Systèmes Perceptifs (UMR8248), Ecole Normale Supérieure

Vendredi 23 novembre 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Retinal projections often poorly represent the structure of the physical world: well-defined boundaries within the eye may correspond to irrelevant features of the physical world, while critical features of the physical world may be nearly invisible at the retinal projection. The challenge for visual cortex is to sort these two types of features according to their utility in interpreting the scene. We describe a novel paradigm that enables selective evaluation of the relative role played by these two feature classes in signal reconstruction from corrupted natural images. Our behavioural and EEG measurements demonstrate that this process is quickly dominated by the inferred structure of the environment, and only minimally controlled by variations of raw image content. The inferential mechanism is spatially global and its impact on early visual cortex is fast. Furthermore, it retunes local visual processing for more efficient feature extraction without altering the intrinsic transduction noise. The basic properties of this process can be partially captured by a combination of small-scale circuit models and large-scale network architectures. Our results challenge compartmentalized notions of bottom-up/top-down perception, and suggest instead that these two modes are best viewed as an integrated perceptual mechanism.
20 novembre 2018

Conférence CerCo

Decoding the neural algorithm of human visual attention for action using hemodynamic and behavioral records

Martin Szinte
Vrije Universiteit Amsterdam, Amsterdam, Netherlands

Mardi 20 novembre 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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24 octobre 2018

Séminaire · invité par Benoit Cottereau Dans Le Cadre Des Cours De Bio-robotique Du M2ncc

Neuroprosthetic solutions in Motor Function Restoration

Christine Azevedo-coste (inria)
Laboratoire d\'informatique, de robotique et de microélectronique de Montpellier (LIRMM)

Mercredi 24 octobre 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Functional Electrical Stimulation (FES) allows to assist movement in persons with sensory-motor deficiencies by activating preserved muscles of paralyzed lower limbs. I will introduce some of the ongoing work in Montpellier CAMIN with examples dealing with the question of controlling FES-induced movements. Different situations will be considered including non invasive and invasive FES solutions in the context of Central Nervous System lesions.
23 octobre 2018

Séminaire · invité par Rufin Vanrullen

The rhythms of attention

Laura Dugue
Maitre de Conferences, Universite Rene Descartes, Paris

Mardi 23 octobre 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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15 octobre 2018

Séminaire · invité par Rufin Vanrullen

Oscillatory processes in the auditory system

Benedikt Zoefel
Cambridge University

Lundi 15 octobre 2018 · 14h Salle de réunion 2eme (Pavillon Baudot), Hôpital Purpan

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2 octobre 2018

Séminaire · invité par Rufin Vanrullen

Get Rhythm:
Object Multiplexing in Phase Neural Networks

Matthew Ricci
Brown University

Mardi 2 octobre 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Convolutional neural networks (CNNs) are the state-of-the-art for natural image classification but they can fail dramatically when interpreting scenes with multiple objects competing for the same representational machinery. On the other hand, recent work in neuroscience indicates that brains circumvent this problem by segregating representations in time via the fine temporal structure of spike trains. Can computer vision take advantage of this principle? In this talk, we will outline recent work concerning the augmentation of artificial neurons in CNNs with variables representing spiking phase with respect to background oscillations. The mathematical basis of these models and their connection to statistical physics will be discussed, their role in unsupervised image segmentation will be analyzed and initial experimental results on an attentional switching task will be presented.
7 septembre 2018

Conférence CerCo

Vestibular Cognition:
Concepts, Confounds, and Conclusions

Fred Mast
Institut für Psychologie, Universität Bern Abteilung Kognitive Psychologie, Wahrnehmung und Methodenlehre www.kog.psy.unibe.ch

Vendredi 7 septembre 2018 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
attention : l'horaire a changé !
warning: schedule changed!
11 juillet 2018

Conférence CerCo

Soutenance de Thèse :
Algorithm-architecture adequacy of spiking neural networks for massively parallel processing hardware

Paul Ferré
CerCo & BrainChip Inc

Mercredi 11 juillet 2018 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

Affiche
27 juin 2018

Conférence CerCo

The Marmoset Monkey as Model for Neurological Disorders

Ingrid Philippens
BPRC(The Biomedical Primate Research Center), Rijswijk, Pays-Bas

Mercredi 27 juin 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Aging societies face an increasing prevalence of neurodegenerative disorders, like Parkinson?s disease (PD) and Alzheimer?s disease (AD), for which no cure exists. The paucity of relevant animal models that faithfully reproduce clinical and pathogenic features of neurodegenerative diseases is a major cause for the lack of effective therapies. Our closest relatives, non-human primates -and in particular the marmoset monkey (Callithrix jacchus)-, provide an appropriate animal model for construct, face and predictive validity owing to the close anatomical and physiological proximity to human.
The marmoset is a small-sized monkey for which several non-invasive behavioural and neurophysiological tests are developed, including sleep-electroencephalogram (EEG) using telemetric techniques for remote-monitoring of brain activity in unrestrained monkeys. Home-cage testing facilitates long-term monitoring of performance alongside collection of neurophysiological data by telemetric means with minimal disturbance to the free moving animal, which fits within the three-R-policy.

Presented are:
?The1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) marmoset model of PD that recapitulates most of the core pathogenic mechanisms of the human condition as well as the prodromal stage for early intervention;
?An immune-activated amyloid-beta model, that makes use of the natural occurring plaque progression in the marmoset, for the most important hallmark of AD. A pro-inflammatory state is increasingly associated with the acceleration of the amyloidopathy that characterizes AD pathogenesis.

These marmoset models offer important opportunities for translational research and development of new treatment modalities for neurological disorders.
26 juin 2018

Séminaire · invité par Tim Masquelier

What has Deep Learning ever done for us? The Convis toolbox for modelling visual responses from retina to cortex built on PyTorch

Jacob Huth

Mardi 26 juin 2018 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Deep convolutional neural nets are a hot topic in machine learning. Their success stems in part from the computational frameworks that were developed for their specific use case, such as Theano, Torch and Tensorflow.
I will present Convis, an open-source Python toolbox for vision modelling that uses PyTorch, to fit and compute a wide range of models, including LN-cascade models, a retina model with local contrast gain control, quadratic models and of course convolution models.
Convis models are not deep-learning models, but geared towards interpretability and bio-plausibility. They feature automated differentiation and gradient based optimization, as well as efficient 3d-convolution operations on GPUs. Non-linear operations such as spike generation and differential equations can also be integrated into the models.
25 juin 2018

Conférence CerCo

Distribution of fixations during natural reading with central field loss.

Eric Castet
Aix-Marseille Université - CNRS - Fédération de recherche 3C

Lundi 25 juin 2018 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
More than one million persons (mostly Age-related Macular Degeneration patients) are blind in their central visual field and have thus great difficulty to read text. Reading with a central field loss (CFL) relies on eccentric vision and requires adaptation of visuo-attentional and oculo-motor processes. Whether using a Preferred Retinal Locus (PRL) during CFL reading can improve reading performance is still an open issue. To address this question, normally-sighted subjects read French sentences with a gaze-contingent artificial scotoma (10°) : they had to read text with a technique allowing to display only one word at a time. For each subject, a fixation map was created by plotting fixation locations with respect to each word's centre. Reading speed of subjects was regressed on several characteristics of their fixation map. Results notably show that reading speed correlates with an upward displacement and an enlargement of fixation distributions. We discuss how these new results constrain current theories of the link between PRL and CFL reading.
21 juin 2018

Conférence CerCo

Deep brain stimulation of the subthalamic nucleus to treat addiction:
frequency matters

Christelle Baunez
Institut de Neurosciences de la Timone, UMR7289 CNRS & AMU (Aix Marseille Université)

Jeudi 21 juin 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The key features of addiction are the motivation for the substance of abuse, the escalated drug intake, the compulsive seeking and taking of the drug, often followed by periods of abstinence that most of the time lead to relapse. The neural mechanisms involved in the transition to addiction remain to be elucidated, as well as the key factors determining why some individuals are vulnerable to addiction while others can pursue drug use in a recreational manner. Using rat models of these various features of addiction, we have shown that the subthalamic nucleus (STN) can be a critical cerebral structure in which electrophysiological activity could serve as a marker of drug craving, or predictive marker of vulnerability to compulsive use. We have also shown that applying deep brain stimulation into the STN can have therapeutic effects on some features of addiction in a frequency manner.
Our results lead to suggest that STN DBS could serve as a surgical strategy to treat addiction and before translation to human drug users, we have developed a non-human primate of drug consumption to validate our hypothesis.
20 juin 2018

Conférence CerCo

Soutenance d'HDR - Intégration multisensorielle :
structures et fonctions

Céline Cappe
CerCo

Mercredi 20 juin 2018 · 13h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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15 juin 2018

Conférence CerCo

Structural and functional connectivity in the human vestibular cortex

Mark Greenlee
Experimental Psychology, University of Regensburg, Germany

Vendredi 15 juin 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The vestibular sensory system signals movements of the head and plays a crucial role for the sensation of self motion. Although the structure and function of the vestibular sense organ in the inner ear are well understood, the further processing of vestibular signals in the cerebral cortex is less clear. Populations of neurons with vestibular tuning are found at multiple sites in the neocortex, but a detailed understanding of the structure and function of this vestibular network has not been established yet. There is good agreement across studies with respect to the location of vestibular activity in the mid-posterior fundus of the Sylvian fissure, which has led to the assumption that this region represents the core of the cortical vestibular network. Following nomenclature in non-human primates, this region has been labeled the parieto-insular vestibular cortex (PIVC). Recent results from our group suggest that vestibular responses are also found in a more posterior site in the Sylvian fissure. These activations coincide with a region in the retroinsular cortex that has been shown to be selective for visual motion processing and has been called the posterior insular cortex area (PIC). In this talk, we review the results of functional and structural MRI studies that point to a role of PIC in vestibular and visual (self-motion) processing. Overall, the results suggest that PIC is a separate area in the vestibular cortex and differs from PIVC in location, connectivity, and function. A similar separation between PIVC and the visual-vestibular posterior Sylvian area (VPS) exists in non-human primates. In analogy to the organization of the visual and auditory cortices, we propose that the vestibular cortex in the Sylvian fissure is subdivided into core (PIVC) and associative regions (PIC), which we refer to together as the PIVC/PIC complex.
5 avril 2018

Conférence CerCo

Les particularités visuelles dans le trouble du spectre de l'Autisme

Magali Batty
CERPPS - Toulouse

Jeudi 5 avril 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Dans le domaine du trouble du spectre de l?autisme, les recherches se sont pendant longtemps consacrées essentiellement à la compréhension des difficultés socio-émotionnelles. Bien qu?initialement décrites dans les travaux princeps de Kanner, les particularités sensorielles ont fait l?objet de peu d?intérêt scientifique lors des dernières années. Mais depuis 2013, le DSM les remet au-devant de la scène.

Nous présenterons, lors de cette conférence, des études récentes visant à caractériser les troubles ophtalmologiques et les fonctions oculomotrices impliquées dans l?exploration visuelle de l?environnement chez des enfants avec un TSA. Ces études nous permettront de mettre en évidence que les particularités visuelles sont non seulement fréquentes mais aussi très envahissantes dans la vie quotidienne, en accord avec les observations cliniques et les témoignages de personnes avec TSA ou de leur entourage.

Il est ainsi possible d?envisager les particularités de l?exploration visuelle et les atypies des activations cérébrales en réponse aux stimuli sociaux (et non sociaux) comme résultantes, au moins en partie, de ces particularités sensorielles.
5 mars 2018

Séminaire · invité par Jean-baptiste Durand

Object recognition:
edge-based 2-D processing or depth-based 3-D processing?

Reza Farivar-mohseni
McGill University

Lundi 5 mars 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Nowadays machines running convolutional neural networks can recognize objects through a huge variety of manipulations?classic ?invariances? of human object recognition, such as size, position, and viewpoint invariance, are also respected by these systems. What is particulary interesting is that convolutional neural networks can achieve such capacity by only using 2-D edge information from static photographcs as inputs. These network models were inspired by our models of the visual system, and thus they are the strongest models we have for understanding object recognition, supplanting elegant 3-D models such as the recognition-by-components (geons). In this talk, I will discuss emerging evidence that neural representation of objects encodes 3-D aspects of the object such as it?s surface structure. I will present evidence from my lab that suggest ventral object representations are sensitive to 3-D because they exhibit depth-cue invariance?the same representations can be tapped by cues as different as texture, shading, structure-from-motion or disparity. The bulk of the evidence would suggest only 3-D representations could have such a quality. These results are discussed in the context of 2-D convolutional models and their limitations in explaining primate object recognition.
14 février 2018

Séminaire · invité par Jean-pierre Jaffrézou

Mendeley - Reference Manager & Academic Social Network

Sarah Rodrigues
Elsevier Masson SAS - Pars

Mercredi 14 février 2018 · 10 hr Salle de conférence (Pavillon Baudot), Hôpital Purpan

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12 janvier 2018

Conférence CerCo

Fly vision and its application to neurological disease

Alex Wade
University of York

Vendredi 12 janvier 2018 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The fruit fly Drosophila Melanogaster is emerging as an important model for studying basic neuroscience and human genetic neurological disease. In humans, the visual system has traditionally provided a
valuable window into both normal and abnormal neurophysiology and methods for assaying human visual function using objective, non-invasive electrophysiological measurements are well established. To generate a comparable assay for flies, we have translated a rapid, non-invasive measurement technique (the steady state visually evoked potential - SSVEP) to Drosophila.

I will describe our SSVEP measurements of contrast response functions and spatiotemporal sensitivity profiles in Drosophila at different ages and in different genetic backgrounds. I will relate these data to
human neurological disease ? specifically Parkinson?s Disease?, autism? and epilepsy and describe parallel work that we are performing with Parkinson's patients in Tunisia. I will also discuss our recent work using flies as in vivo screens for novel therapeutic compounds and using machine learning algorithms to classify mutant flies based solely on their visual response.

Finally, we find that flies respond to spatial frequencies well above the sampling Nyquist limit. I will discuss whether the ability to detect aliased information of this type should be considered as a feature or, so to speak, a ?bug? in the insect visual system.?
2017 36
12 décembre 2017

Conférence CerCo

Simultaneous spatial representations in visual cortex and hippocampus

Julien Fournier
Cortical Processing Laboratory, University College London

Mardi 12 décembre 2017 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Animals rely on multiple navigational signals to estimate their own position in an environment. They can use vision to update their estimate based on visual landmarks. They can also perform path integration, i.e. estimate the distance they traveled from the previous location. Path integration and visual landmarks both contribute to the spatial representation in hippocampus. However, it is yet unclear whether navigational signals influence neural processing in sensory areas like the primary visual cortex (V1).
We trained mice to lick in a specific position of a virtual reality corridor for water reward. On some trials, the gain of the virtual environment was changed so the animal had to run 20% more, or less, to reach the reward location, while visual landmarks remained at the same position along the corridor.
While the mice performed the task, we recorded simultaneously from V1 and CA1 neurons. As expected, the activity of CA1 place cells depended on both visual cues and distance traveled. Surprisingly however, V1 neurons revealed a similar behavior: the position decoded from the V1 population was intermediate between predictions based on visual cues and distance traveled. Our results thus suggest a control of V1 activity by path integration. We propose that this control could rely on feedback position signals from the navigational system or on a direct influence of the distance traveled by integrating visual flow and self-motion signals.
12 décembre 2017

Conférence CerCo

Three talks :
1.MRI to investigate the complexity of the CSF flows and its interactions with the cerebral blood flows. by Olivier Baledent, Laboratoire BioFlowImage, Université de Picardie Jules Verne. 2. 1D model of blood/CSF coupling in the cranio-spi

Mini Symposium Brain Flows 10h30 - 13h30

Mardi 12 décembre 2017 · 10h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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7 décembre 2017

Conférence CerCo

Cortical and subcortical dynamics during human decision making

Julien Bastin
Grenoble Institute of Neuroscience, INSERM U1216 France

Jeudi 7 décembre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Deciding on the best course of action amongst a range of competing alternatives has been a fundamental problem that has been addressed in numerous cognitive neuroscience studies so as to clarify the computations that we carry out in order to make decisions as well as the neural implementation of those computations. Decision making can be broken down into several basic processes involving the construction of a mental representation of the decision problem, the valuation of different actions under consideration and the selection of one action on the basis of their valuations. After implementing the decision, the brain also needs to estimate the desirability of outcomes that follow and use this estimation so as to update the other decision processes to improve the quality of future decisions (Rangel et al., 2008). During this talk, I will present some recent findings we made in this field thanks to a methodology that consists in creating behavioral paradigms to isolate specific decision making processes in order to examine the neural dynamics mediating these computations using human invasive electrophysiological methods (local field potentials and single-unit recordings). For example, we used a stop signal task to show that two different neuronal populations within the human subthalamic nucleus encode motor and executive control, while at the cortical level, we found that an error-monitoring signal emerge in the anterior insular cortex and could correspond to an input decision signal sent to the dorsomedial prefrontal cortex, as suggested by granger causality analyses. Ongoing work in our lab is now dealing with the identification and modulation of the brain dynamics underlying reinforcement learning.
5 décembre 2017

Conférence CerCo

Le microcèbe, un modèle primate pour l'étude du vieillissement.

Fabien Pifferi
UMR 7179, équipe BIOADAPT, Brunoy

Mardi 5 décembre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
c'est dans une demi-heure, merci à tous
4 décembre 2017

Conférence CerCo

Etude des fonctions exécutives chez le marmouset:
effet du vieillissement dans un environnement semi-naturel

Amirouche Sadoun
Défense de thèse.

Lundi 4 décembre 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Cette présente thèse a permis d?acquérir un corpus de données importantes qui valident
un nouveau modèle animal d?étude du déclin cognitif lié à l?âge, le marmouset commun
(Callithrix jacchus). Un ensemble de tâches comportementales ont été effectuées par nos
animaux sur écran tactile dans un contexte semi-naturel. Les résultats permettent de comprendre
et caractériser les divers déficits présents chez les sujets âgés et de découvrir, via une méthode
d?analyse algorithmique, les périodes d?âge clés où ceux-ci apparaissent. La présence de déficits
précoces souligne l?intérêt du modèle dans l?optique des pathologies dégénératives du cerveau.
De plus, les analyses des données morphométriques obtenues par IRM structurale ont révélé
certaines anomalies anatomiques pouvant apparaître chez les individus âgés. Également,
l?analyse des enregistrements audio que nous avons obtenus pendant les sessions
comportementales a montré l?existence d?une influence de l?environnement sonore et
particulièrement de certaines vocalisations sur les performances cognitives. Ce résultat souligne
l?importance de mener les expérimentations dans un contexte semi-naturel tel que le nôtre. Il
met également l?accent sur l?importance de mener ce genre d?approche et de l?adapter pour une
meilleure compréhension du rôle du vieillissement dans la cognition sociale. L?ensemble de
notre travail permet ainsi paver le chemin à de nouvelles voies de recherche fondamentale et
clinique intéressantes et prometteuses.
Mots clés : Marmouset, vieillissement cognitif, contrôle inhibiteur, mémoire de travail,
IRM, vocalisations.
29 novembre 2017

Conférence CerCo

Mini-symposium - Investigating single neurons, neuronal circuits and cortical networks in macaque monkeys

Suliann Ben Hamed, Patrizia Fattori, Koen Nelissen, Michael Schmid
CNRS UMR 5229 Lyon, Université de Bologne, Université Catholique de Leuven, Université de Newcastle

Mercredi 29 novembre 2017 · 10h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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28 novembre 2017

Conférence CerCo

Visuotopie et traitement du flux optique chez le singe:
une investigation par IRMf

Samy Rima
Défense de thèse - CERCO

Mardi 28 novembre 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Le développement de l?IRMf (Imagerie par Résonance Magnétique fonctionnelle) chez des primates non-humains (PNH) a instauré la possibilité d?établir le lien tant attendu entre les données issues d?études invasives chez le PNH et celles d?imagerie fonctionnelle obtenues chez l?humain. Cette technique représente un progrès important car elle permet la réduction et le raffinement des protocoles invasifs impliquant des primates non humains, en révélant les régions d?intérêts dans lesquelles les approches focales invasives, électrophysiologiques ou anatomiques, devraient être menées. Par ailleurs, les connaissances acquises avec ces approches invasives peuvent être transposées plus aisément à l?homme, une fois que les homologies et différences interspécifiques ont été identifiées au travers de protocoles d?IRMf menées en parallèle chez les primates humains et non-humains. Conscient des avantages que fourni le modèle PNH, l?objectif primordial de cette thèse était le développement de la technique IRMf chez le singe éveillé au CerCo (Centre de recherche sur le cerveau et la cognition) à Toulouse, afin d?étudier l?organisation fonctionnelle de la voie dorsale chez cette espèce et de la comparer avec celle de l?Homme. Les résultats de 2 études révèlent chez le singe un nouvel assemblage d'aires visuotopiques dans le cortex intraparietal postérieur d'une part, et un réseau d'aires corticales impliquées dans le traitement du flux optique compatible avec le mouvement de soi d'autre part. En plus d'apporter une perspective nouvelle sur l'organisation fonctionnelle du cortex visuel chez les primates non humains, ces études illustrent la contribution de l?IRMf singe comme pont entre études électrophysiologiques chez les primates non humains et études d'imagerie fonctionnelle chez l'homme.
23 novembre 2017

Conférence CerCo

Neurogenic control of neurovascular coupling

Bruno Cauli
Neuroscience Department Paris Seine

Jeudi 23 novembre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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22 novembre 2017

Conférence CerCo

Soutenance de thèse :
Ectonucléotidases, adénosine et transmission synaptique

Marie Gleizes
Centre de Recherche Cerveau et Cognition, CNRS

Mercredi 22 novembre 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Dans le cerveau, les fonctions de la phosphatase alcaline non spécifique des tissus (TNAP) ne sont pas clairement identifiées. La localisation et l’expression de cette enzyme au niveau neuronal suggère cependant, qu’elle joue un rôle important dans le développement et le fonctionnement du cerveau. Cela est supporté par la présence de graves crises d’épilepsie chez les humains porteurs d’une mutation de la TNAP. Ces crises d’épilepsie sont létales chez les souris KO pour la TNAP. Des études chez la souris montrent que la TNAP pourrait réguler l’inhibition postsynaptique médiée par le GABA et elle pourrait être impliquée dans l’inhibition présynaptique médiée par l’adénosine. L’adénosine est, en partie, synthétisée via la déphosphorylation successive de l’ATP en ADP puis en AMP par des ectonucléotidases. Parmi elles, la TNAP et l’ecto-5’-nucléotidase (NT5E) catalysent l’hydrolyse de l’AMP en adénosine dans le cortex cérébral. L’adénosine agit principalement au niveau pésynaptique par l’intermédiaire des récepteurs A1. Ainsi l’adénosine a une influence sur la transmission synaptique et sur la plasticité synaptique. Ceci pourrait expliquer, en partie, les crises d’épilepsie observées chez les souris KO pour la TNAP. Les deux objectifs principaux de ma thèse ont été : (1) évaluer la contribution de la TNAP dans la production d’adénosine dans le cerveau ; (2) étudier l’influence de l’adénosine sur la plasticité synaptique.
Premièrement, l’étude de la contribution de la TNAP dans la production d’adénosine dans le cerveau a été réalisée au moyen de deux approches complémentaires. Une approche métabolomique (spectroscopie RMN du proton) sur des cerveaux entiers de souris KO pour la TNAP a permis de montrer que la TNAP participe, entre autre, à la synthèse d’adénosine dans le cerveau. Une deuxième approche, électrophysiologique sur tranches de cerveaux de souris in vitro, nous permet d’examiner les conséquences de l’inhibition des ectonucléotidases intervenant dans la synthèse de l’adénosine. Elle a révélé que l’inhibition des ectonucléotidases (TNAP et NT5E) ne supprime pas l’effet inhibiteur de l’AMP médiée par les récepteurs A1.
Deuxièmement, nous avons étudié l’influence de l’adénosine sur la plasticité synaptique à courte terme. Nous avons enregistré des potentiels de champs dans la couche Ia du cortex piriforme en réponse à des stimulations eélectriques (3,125 a? 100 Hz) présentée avec des fréquences recouvrant la gamme d’oscillations physiologiques. Nos résultats montrent qu’avec de fortes concentrations d’adénosine, la facilitation est accentuée par rapport à celle observée en situation contrôle. Cet effet est observé pour des fréquences supérieures ou égales à 25 Hz. De plus, cette accentuation est d’autant plus grande que la fréquence est élevée (maximum atteint à 100 Hz pour 100 ?M). En bloquant l’action de l’ade?nosine endogéne, l’effet contraire est observé : une facilitation déficitaire par rapport au contrôle et dont le défaut est croissant avec la fréquence de stimulation.
Tous ces résultats convergent vers l’hypothèse qu’une déficience en TNAP, traduite par une absence d’adénosine, pourrait contribuer au maintien des processus épileptiques géneérés par un déséquilibre de l’inhibition et de l’excitation dû à une diminution de GABA. L’effet inhibiteur de l’AMP médié par les récepteurs A1 ne serait pas suffisant pour contrecarrer les crises d’épilepsie observées chez les sujets hypophosphatasiques et les souris KO pour la TNAP.
27 octobre 2017

Conférence CerCo

Towards a "Neuro-Encryption" system:
from understanding the role of brain oscillations in vision to controlling perception

Saskia Brüers
Centre de Recherche Cerveau et Cognition, CNRS

Vendredi 27 octobre 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Our brain activity is inherently rhythmic: oscillations can be found at all levels of organization. This rhythmicity in brain activity gives a rhythm to what we see: instead of continuously monitoring the environment, our brains take ?snapshots? of the external world from 5 to 15 times a second. This creates perceptual cycles: depending on the phase of the underlying oscillation, our perceptual abilities fluctuate. Accumulating evidence shows that brains oscillations at various frequencies are instrumental in shaping visual perception.
At the heart of this thesis lies the White Noise Paradigm, which we designed as a tool to better understand the influence of oscillations on visual perception and which ultimately could be used to control visual perception. The White Noise Paradigm uses streams of flashes with random luminance (i.e. white noise) as stimuli, which have been shown to constrain brain oscillations in a predictable manner. The impulse response to WN sequences has a strong (subject specific) oscillatory component at ~10Hz akin to a perceptual echo. Since the impulse response is a model of how our brains respond to one single flash in the sequence, they can be used to reconstruct (rather than record) the brain activity to new stimulation sequences. We then present near-perceptual threshold targets embedded within the WN sequences and extract the time course of these predicted/reconstructed background oscillations around target presentation. Thus, the reconstructed EEG can be used to study the influence of the oscillatory components on visual perception, independently of other types of signals usually recorded in the EEG.
First, we validate the White Noise Paradigm by showing that: 1) the WN sequences do modulate behaviour, 2) the perceptual echoes evoked by these WN sequences are stable in time, 3) they are a (relatively) good model of the subject?s recorded brain activity and 4) their neuronal basis can be found in the early visual areas.
Second, we investigate the relationship between these constrained brain oscillations and visual perception. Specifically, we show that the reconstructed EEG can help us recover the true latency at which (theta) phase influences perception. Moreover, it can help us uncover a causal influence of (alpha) power on target detection, independently from any fluctuation in endogenous factors.
Finally, capitalizing on the link between oscillations and perception, we build two algorithms used to control the perception of subjects. First, we build a ?universal? forward model which can predict for any observer whether a particular target will be seen or not. Second, we build a subject-dependent model which can predict whether a particular subject (for whom EEG was recorded previously) will perceive a given target or not. Critically, this can be used to present targets optimized to be perceived by one subject only, to the detriment of all other subjects, creating a sort of ?Neuro-Encryption? system.
27 octobre 2017

Séminaire · invité par Sasskia Brüers

The effects of attention and visual input on noninvasive electrophysiological indices of natural speech processing at different hierarchical levels

Edmund Lalor
University of Rochester Medical Center

Vendredi 27 octobre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
How the human brain extracts meaning from the dynamic patterns of sound that constitute speech remains poorly understood. This is especially true in natural environments where the speech signal has to be processed against a complex mixture of background sounds. In this talk I will outline efforts over the last few years to derive noninvasive indices of natural speech processing. I will discuss how these indices are affected by attention and visual input and how attentional selection and multisensory integration can be ?decoded? from EEG data. I will outline work showing that EEG and MEG are sensitive not just to the low-level acoustic properties of speech, but also to higher-level linguistic aspects of this most important of signals. This will include demonstrating that these signals reflect processing at the level of phonetic features. And, based on our most recent work, it will also include evidence that EEG is exquisitely sensitivity to the semantic processing of natural, running speech in a way that is very strongly affected by attention and intelligibility. While showcasing these findings, I will outline a number of paradigms and methodological approaches for eliciting noninvasive indices of speech-specific processing that should be useful in advancing our understanding of receptive speech processing in particular populations.
19 octobre 2017

Conférence CerCo

The neural basis of adaptive cognitive control :
beta oscillations, feedback and dopamine

Charlie Wilson
Stem Cell and Brain Research Institute INSERM U1208

Jeudi 19 octobre 2017 · 11h RDC du PPR, centre d\\\'enseignement et de Congrés, Hôpital Purpan

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Résumé
The process of adapting behaviour to current circumstances occurs over many timescales ? we respond to immediate feedback to detect errors, we implement differing levels of cognitive control to adapt to that feedback, and we adjust effort over the hours of a task. A set of neurophysiological responses in the frontal lobes, including feedback responses and beta oscillations, as well as the dopaminergic system, are implicated in all of these levels of adaptation. I will show how these markers have multiple and differentiable roles at different timescales, using data from macaque monkeys providing longitudinal electrophysiology whilst performing cognitive tasks, and subsequently using a slow dopamine depletion.
Feedback potentials provide an immediate response that differentiates between different valences of feedback. This response might be thought to drive trial-by-trial control and adaptation, but in fact a slow dopamine depletion that removes the valence coding of these potentials does not impair trial-by-trial control. The potentials are therefore more likely associated with a longer-term motivational function.
Beta oscillations during the delay period (in which the upcoming decision is made) are modulated by both trial-by-trial control levels and also attentional effort changes across multiple trials within the session. Again, the trial-by-trial element of this response is not impacted by dopamine lesion. Importantly, however, dopamine lesion modulates how beta oscillations encode for longer-term motivational factors, and at the same time the monkeys? motivation for the task is altered.
Single trial analysis of these beta oscillations shows them to be burst phenomena (rather than a sustained oscillation). Analysis of burst properties reveals how beta oscillations can be independently modulated by different control requirements over different timescales. As such burst analysis is essential to a precise understanding of the true role of oscillatory phenomena.
Together these data reveal the neurophysiological basis of cognitive control functions in frontal cortex, and how similar markers can seemingly account for multiple timescales of adaptation.


Support: Marie Curie IEF to CREW: ?Reversible Cognition? 273790; LabEx Cortex: ANR-11-LABX-0042; Fondation Neurodis; Fondation de France; Fondation CERAL; ANR.
6 octobre 2017

Conférence CerCo

From dynamics to computations in cortical networks

Srdjan Ostojic
ENS Paris

Vendredi 6 octobre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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3 octobre 2017

Conférence CerCo

Cognition with a one-neuron brain

Romain Brette
Institut de la Vision

Mardi 3 octobre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Recent years have seen the rise of large-scale measurement techniques in neuroscience, such as connectomics and the measurement of the activity of large neural populations or even of an entire nervous system. The motivation is that all neurons in a brain are interdependent, and therefore a systemic approach is required. It is not clear however how such massive data will be analyzed and interpreted. I propose to start more modestly by investigating the relation between physiology and cognition in a one-neuron brain. Paramecium is a unicellular organism which swims in fresh water using cilia. It eats bacteria and finds them by following chemical gradients, it avoids obstacles and predators, it finds sexual partners. It can also be seen as a swimming neuron: various types of stimuli can depolarize its membrane, triggering an action potential which in turn triggers a change in swimming direction. I will show how this one-neuron brain is capable of spatial cognition, through the interaction with the environment. This zero-connectome brain is a challenge to the idea that function is determined by the connectome (radical connectionism) and points to the importance of embodiment. Finally, this simple sensorimotor model will allow me to revisit popular themes in theoretical neuroscience from a systemic viewpoint, including coding, noise, adaptation, robustness, and multisensory integration.
2 octobre 2017

Conférence CerCo

HDR - Spike-based computing and learning in brains, machines, and visual systems in particular

Timothée Masquelier

Lundi 2 octobre 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
We have first shown that, thanks to the physiological learning mechanism referred to as spike timing-dependent plasticity (STDP), neurons can detect and learn repeating spike patterns, in an unsupervised manner, even when those patterns are embedded in noise, and the detection can be optimal. Importantly, the spike patterns do not need to repeat exactly: it also works when only a firing probability pattern repeats, providing this profile has narrow (10-20ms) temporal peaks. Brain oscillations may help in getting the required temporal precision, in particular when dealing with slowly changing stimuli. All together, these studies show that some envisaged problems associated to spike timing codes, in particular noise-resistance, the need for a reference time, or the decoding issue, might not be as severe as once thought. These generic STDP-based mechanisms are probably at work in particular the visual system, where they can explain how selectivity to visual primitives emerges, leading to efficient object recognition. High spike time precision is required, and microsaccades could help. All these mechanisms are appealing for neuromorphic engineering applications. They can lead to fast, energy efficient systems which can learn online, in an unsupervised manner.
27 septembre 2017

Conférence CerCo

Making Sense of Real-World Scenes

Chris Baker
NIH

Mercredi 27 septembre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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26 septembre 2017

Conférence CerCo

HDR defense

Leila Reddy
CerCo

Mardi 26 septembre 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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25 septembre 2017

Séminaire · invité par S. Thorpe

Non-invasive and invasive recordings of the brains of humans during naturalistic stimulation

Julien Dubois
Cedars-Sinai Medical Center // Caltech

Lundi 25 septembre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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22 septembre 2017

Conférence CerCo

Noisy and ambiguous stimuli to probe adaptive processes in audition

Daniel Pressnitzer
Laboratoire des Systèmes Perceptifs, Ecole Normale Supérieure (Paris)

Vendredi 22 septembre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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21 septembre 2017

Séminaire · invité par Simon Thorpe

Attentional dynamics in complex natural environments:
Evidence from magic in toddlers

James Riviere
Département de Psychologie - Psychologie et Neurosciences de la cognition et de l\'affectivité- Université de Rouen

Jeudi 21 septembre 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
How visual attention drives the search behavior is still poorly described in young children. Using magic in toddlers, we investigate how attentional dynamics induce constraints in choosing an action to perform and how this interacts with decision-making processes and choices. In our talk, we will present three paradigms involving attentional misdirection and performing under naturalistic conditions (e.g., the task is performed live to each participant). We developed these paradigms with the aim of understanding the interplay between attentional biases and cognitive heuristics in the selection of action. Our results suggest that the attentional focus effect that occurs in some magic tricks is not purely stimulus driven and based on the cue?s saliency alone (i.e., the experimenter?s hand motion); rather, it relies on top-down influences that direct attention toward a cue only if its feature is relevant in finding the hidden object. We argue that using magic to study limited attention in young children may help us understand more about the attentional-processing limitations in adults.
4 septembre 2017

Conférence CerCo

Probing and manipulation of brain oscillations & associated functions by transcranial stimulation and EEG

Gregor Thut
University of Glasgow

Lundi 4 septembre 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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7 juillet 2017

Conférence CerCo

Thesis Defense :
"Bringing very long-term memories back to mind"

Christelle Larzabal
CerCo

Vendredi 7 juillet 2017 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Rodrigo Quiroga (rapporteur)
Aude Oliva (rapporteur)
Laurence Taconnat (examinateur)
Lluis Fuentemilla (examinateur)
Simon Thorpe (directeur de thèse)
7 juillet 2017

Conférence CerCo

Memory formation and long-term coding in the human hippocampus.

Professor Rodrigo Quian-quiroga
Centre for Systems Neuroscience, University of Leicester, UK

Vendredi 7 juillet 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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3 juillet 2017

Conférence CerCo

Thesis Defense :
Complexité de l'intégration multisensorielle chez le primate humain et non humain :
du comportement à l?électrophysiologie corticale et sous corticale.

Cécile Juan
CerCo

Lundi 3 juillet 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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19 juin 2017

Conférence CerCo

Localization of moving objects in perception and action

Matteo Lisi
Department of Optometry & Visual Science School of Health Science City, University of London

Lundi 19 juin 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Our visual system allows us to localize objects in the world and plan motor actions toward them. Whether the same information or computations are used in the two tasks, and more generally in perception vs. action, is a highly debated question. I will present a series of studies providing evidence for dissociation in how visual location is computed between perception and different types of actions. In these studies we have examined the localization of a moving aperture that drifts in one direction with an internal pattern that drifts in the orthogonal direction (a double-drift stimulus). When seen in peripheral vision, the internal drifting motion induces large misperception of the aperture motion, producing an error in its perceived position that accumulates across up to 1s of its motion and makes the apparent orientation of its path deviates by 45° or more from the physical path. Despite the perceptual distortion, saccadic eye movements made to this double drift target track the actual location quite faithfully, showing only a small, local shift in response to the internal motion that does not accumulate over time. The dissociation does not seems to depend on different parameters for motion integration (smooth pursuit eye movements followed the perceived, and not the physical, direction) but rather on how current visual input is combined with information in memory: the dissociation was abolished when saccades were memory-guided and online visual information about the target not available. Other types of actions, such as pointing hand movements, showed a large bias consistent with the perceptual illusion. Taken together, these results highlight a fundamental difference between perception and gaze control, suggesting that while our perceptual experience builds upon the history of previous sensory signals, visually-guided eye movements use only the most recent information available.
8 juin 2017

Conférence CerCo

Probing the functional cortical impact of retinal prosthesis

Frédéric Chavane
Institut des Neurosciences de la Timone (INT, Marseille)

Jeudi 8 juin 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Retinal prostheses are promising tools for recovering visual functions in blind patients but, unfortunately, with still poor gains in visual acuity. Improving their resolution is thus a key challenge that warrants understanding its origin through appropriate animal models. Here, I will describe a systematic comparison between visual and prosthetic activations of the rat primary visual cortex (V1). We established a precise V1 mapping as a functional benchmark to demonstrate that sub-retinal implants activate V1 at the appropriate position, scalable to a wide range of visual luminance, but with an aspect-ratio and an extent much larger than expected. Such distorted activation profile can be accounted for by the existence of two sources of diffusion, passive diffusion and activation of ganglion cells? axons en passant. Reverse-engineered electrical pulses based on impedance spectroscopy is the only solution we tested that decreases the extent and aspect-ratio, providing a promising solution for clinical applications. I will discuss the perspective and the future direction of this work.
11 mai 2017

Conférence CerCo

2D - 3D - fake 3D - and genuine reality

Heiko Hecht
Johannes Gutenberg Universität, Mainz, Germany

Jeudi 11 mai 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Does the action hero look more powerful and more intelligent when we see the movie in 3D? This is indeed the case. But why is this so? And does 3D ? if it has the power to change impressions ? also alter such basic perceptual feats as size and distance perception? The latter does not seem to be the case for objects placed outside our personal space. We present a number of experiments performed in real-world settings, in 2D-pictures, and in 3D-viewing set-ups to narrow down the perceptual effects of 3D-environments. We conclude that such effects can alter highly robust perceptual phenomena, such as the Mona Lisa effect. At the same time, 3D effects do not have to be very sophisticated in order to exert their influence.
9 mai 2017

Conférence CerCo

Perceiving a stable world through the predictive allocation of attention

Martin Szinte
Ludwig-Maximilians-Universität Münich

Mardi 9 mai 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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21 avril 2017

Séminaire · invité par Rufin Vanrullen

The role of feed-forward and feed-back mechanisms in cognitive control

Shahd Al-janabi, Phd
University of Wisconsin-Milwaukee

Vendredi 21 avril 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Human behaviour flexibly adapts to subtle changes in the environment - an ability that is important for psychological health, learning, and day-to-day functioning. The mechanism that prevents behaviour from remaining rigid (when our goals change) is cognitive control: a construct that is associated with a wide range of processes, including the prioritisation of information, and the preparation of a motor response. The implementation of cognitive control is traditionally thought to require consciousness; that is, humans prioritise information or prepare a motor response only when they know the reasons for, and the consequences of, such a behaviour. Recent research, however, shows that several behavioural phenomena - that represent instances of cognitive control - can be triggered by events of which humans are not aware. These studies beg the following question: what aspects of cognitive control can be achieved without conscious awareness of the trigger, and for what is conscious awareness of the trigger necessary? In this talk, I will examine this question by overviewing studies that seek to elucidate the role of conscious awareness in cognitive control using psychophysics, functional imaging and neuronal stimulation/interference. The talk will cover, specifically, whether or not humans can prioritise spatial locations, and modify an on-going motor response, without awareness of the environmental trigger. This research aims to provides critical information about the interplay between conscious awareness and cognitive control, and understand the way in which humans flexibly navigate an ever changing environment.
5 avril 2017

Séminaire · invité par Rufin Vanrullen

Unconscious learning:
when your brain knows more than you do

Andrea Alamia
Université Catholique de Louvain, Belgique

Mercredi 5 avril 2017 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
It is believed that a substantial part of our cognition relies on unconscious mechanisms: we constantly learn things and make decisions without awareness. For decades, cognitive neuroscience investigated unconscious processing in different domains: from sequence to statistical learning and from artificial grammar to contextual cueing. Nevertheless, its nature is still controversial, leading to lively debates in the recent years.
In the first part of this talk, I will present the results of our new experimental design, addressing the main criticisms of unconscious learning. In our task, participants had to report the motion direction of a colored patch of dots. Unbeknownst to them, two of three possible colors were always associated with the same motion direction/response, while the third color was uninformative. We found that participants systematically learned the association between color and motion direction, while remaining strikingly unaware of it. In a series of additional experiments we further investigated the underlying behavioral mechanisms, the role of trial-by-trial feedback and the nature of the learned association.
The second part of the talk will be focused on the relationship between learning and visual attention (e.g. eye movements). After a brief overview of the current models, I will present our studies showing how visual attention is biased by implicitly learnt statistical regularities, and how eye movements are affected by unconscious knowledge.
Finally, we will discuss our search for physiological markers of implicit statistical learning. In a series of 4 experiments, we show for the first time that pupil size tracks the violation of statistical regularities, even when these are not explicitly perceived. In the last of these experiments, we found the EEG correlates of this pupillary response in the right frontal electrodes, in agreement with the current literature.
All in all, our results provide a novel robust framework to study behavioral and physiological landmarks of unconscious learning.
22 février 2017

Conférence CerCo

The vestibular system:
balancing more than just the body

Christophe Lopez
Laboratoire de Neurosciences Intégratives et Adaptatives - UMR 7260 CNRS - Aix Marseille Université

Mercredi 22 février 2017 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
http://lnia.fr/corps-et-cognition/lopez-christophe/
17 février 2017

Conférence CerCo

Soutenance de la these/PhD Defense. Investigating the role of oscillations in endogenous and exogenous attentional states:
novel methods in neurophenomenology

Tracy Brandmeyer
CNRS CerCp

Vendredi 17 février 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Research suggests that people engage in some form of mind wandering that is unrelated to the task at hand ~50% of waking hours. While engaged in mind wandering, people consistently report experiencing greater negative affect when compared to reports of being task focused (Killingsworth & Gilbert, 2011). The cornerstones of most meditation and contemplative practices involve training the continuous and flexible monitoring of ongoing thoughts and sensory experience, and the cultivation of sustained focus and attention. Given that we are generally unaware of mind wandering when it occurs and the consequential methodological challenges this poses, meditation practitioners may provide more accurate phenomenological reports and descriptions of these temporally fluctuating states given their respective training. We designed a novel paradigm based on experience sampling to gain insight into the dynamic measures of mental activity and EEG during meditation. Our findings suggest that meditation expertise is associated with an attenuated frequency of mind wandering, and that meditation training reduces the susceptibility of the mind to wander subsequently leading to longer periods of sustained meditative absorption. Increases in theta activity (4-7 Hz) over frontal midline regions of the cortex, and alpha activity (9-12 Hz) primarily focused over the somatosensory cortex, appear to be markers of sustained attentional states when compared to reported mind wandering trials. Based on the robustness of the frontal midline theta in advanced meditators, alongside a multitude of findings demonstrating that frontal theta may serve as the backbone for cognitive control via long range information integration in neural networks throughout the brain, we then developed a methodologically novel and exhaustive neurofeedback protocol with the aim of training frontal midline theta (3.5-6.5 Hz at electrode site Fz) by means of instructing our subjects to engage in focused breathing and other techniques similar to meditation. After eight training sessions, we found that subjects who received online neurofeedback were able to significantly increase theta activity (3-7 Hz) over frontal regions, whereas subject?s receiving age and gender matched pseudo feedback were not. We additionally observed significant modulations in both the alpha (9-11 Hz) and beta bands (13-20 Hz) in subjects who received the online neurofeedback training, as well as changes in executive performance on several tasks. These findings provide new evidence that we can successfully close the causal loop between specific neural substrates and specific behaviors.
16 février 2017

Conférence CerCo

From Neurophenomenology to Brain-Computer-Interfaces:
Refining neuroimaging methods for integrating subjective experience

Michel Le Van Quyen, Ulrich Ott And Hein Van Schie
INSERM (Paris), the Bender Institute of Neuroimaging (Geissen, Germany) and the Donders Center for Cognitive Neuroimaging (Nijmegen, Netherlands)

Jeudi 16 février 2017 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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23 janvier 2017

Conférence CerCo

Corticocortical effective connectivity in congenital deafness

Andrej Kral
Chair and Professor of Auditory Neurophysiology, Medical University Hanover

Lundi 23 janvier 2017 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
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18 janvier 2017

Séminaire · invité par Elodie Despouy

Trisdesclous, a new generation tools for "spikes sorting" :
torwards an online spike sorting

Samuel Garcia
Ingénieur CRNL Lyon

Mercredi 18 janvier 2017 · 14h30 Salle de réunion 2eme (Pavillon Baudot), Hôpital Purpan

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Résumé
Ami(e)s electrophysiologistes, venez découvrir le dernier outil de spikesorting dernier cri : Tridesclous
Développé par Christophe Pouzat et Samuel Garcia, tridesclous est un outil de spike sorting utilisable par tous.
Semi manuel, il a une approche en 2 étapes:
1- la partie construction du catalogue ("clustering"), semi manuelle
2- la partie épluchage ("template matching"), automatique.
C'est rapide, c'est beau et ça pourra même être utilisé "online" dans un futur proche.
13 janvier 2017

Conférence CerCo

From reward processing to social decision making:
Insights from intracranial recordings and model-based fMRI in humans

Jean-claude Dreher
Centre de Neurosciences Cognitives, Lyon

Vendredi 13 janvier 2017 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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2016 22
20 décembre 2016

Conférence CerCo

Soutenance de la these:
When noise enlightens:
an investigation into the mechanisms of perception and long-term memory for meaningless auditory stimuli.

Jayalakshmi Viswanathan
CerCo CNRS UMR 5549

Mardi 20 décembre 2016 · 14h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Humans are able to detect acoustic features in Gaussian noise. Researchers recently used repeating noise segments [cyclic noises (CNs), presenting a
segment of noise several times back to back] to investigate long-term sensory memory (Agus et al., 2010). They asked participants to discriminate CNs from plain noise, while implicitly presenting them with a few target CNs several times. The results demonstrated long-term memory for such sounds, which have raised several further questions. First, the robustness of memory for implicitly learned Gaussian sounds was tested using a similar paradigm. Participants? recognition memory was tested by presenting them with looped and scrambled (10 or 20-ms bin size) versions
of target CNs 4 weeks post-learning. Our results suggest that neurons might code for very small bits of acoustic information (10 ms). Next, the
spatial correlates of memory, specifically, the role of subcortical areas in storing auditory patterns was investigated. Using the same paradigm,
participants performed the testing session during fMRI scanning. Implicit memory for target CNs was demonstrated and functional contrasts implicate
the Medial Geniculate body and hippocampus. Lastly, we explored the mechanisms and resolution limits of this memory. Participants were presented with CNs in one ear and plain noise in the other ear, and had to localize the CN. Implicit and explicit memory for target CNs was tested 4
weeks later. Although participants lacked conscious memory, they were better at localizing target 10-ms CNs than novel CNs, even with 8 repeats
(80 ms). Surprisingly, neural correlates explored using brainstem evoked potentials demonstrated short-term memory effects within a few milliseconds of sound presentation. Altogether we demonstrate: 1) the ability to learn and store short acoustic patterns (10 ms); 2) this memory is sub-cortical, in regions implicated in perception of sounds; and 3) these results are compatible with an STDP model of learning.
19 décembre 2016

Conférence CerCo

Agency, Action and the prediction of sensory outcomes.

Andrea Desantis
Laboratoire Psychologie de la Perception CNRS / Université Paris Descartes

Lundi 19 décembre 2016 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
During my career, I developed a strong interest in the human sense of agency and in how our brains can tell the difference between what we cause in the world and what is caused by others. This ability is what allows humans to have a sense of self as well as a sense of responsibility for what their actions cause. Thus, far I have investigated various aspects of this question, focusing on human voluntary actions. In particular, I have worked on defining the differences in perceiving effects that are caused by our own voluntary actions, from perceiving effects that are caused externally. One of the main findings of this work was that an important difference between the events we cause and those caused externally is how efficiently we can predict them. During my talk, I will present studies focusing on our ability to predict the outcomes caused by our actions. I will also give a description of my research background and I will outline the questions that I would like to investigate if my ATIP-avenir application is successful.
2 novembre 2016

Conférence CerCo

A tale of three "omes":
Dynamics of Functional Interactions

Demian Battaglia
Institut de Neurosciences des Systèmes UMR 1106; Aix-Marseille Université

Mercredi 2 novembre 2016 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The structural "connectOME", one of the holy grails of recent large-scale initiatives in neuroscience, plays an important role in shaping functional interactions between neurons or neuronal populations. However the link between structural and (directed) functional connectivity is indirect and mediated by the emergent complexity of the dynamics developed by the considered neuronal circuits. In particular, different dynamical states can give rise to radically different topologies of functional interaction and information routing in virtual absence of structural changes. The spontaneous activity of neural circuits has been interpreted as a noise-driven exploration of a repertoire of internally available meta-stable dynamical states (named "dynOME" by Nacy Kopell and co-workers), which are transiently visited over time in a stochastic fashion. If a correspondence exists between dynamical states and functional interaction modes, we would thus expect a marked and characteristic time-dependency of functional connectivity networks (tracked by analyses of the so-called "chronnectOME"), possibly manifesting inter-state transitions.

We will consider here functional connectivity dynamics in simulated systems at different scales. First, we will present mean-field and spiking simulations of toy brains involving a few brain areas only, and study how the controllable switching between different types of oscillatory patterns can lead to the flexible, self-organized reconfiguration of inter-regional information routing. Such findings generalize to the realistic case in which oscillatory episodes occur as highly stochastic and short-lived transients.

Shifting then up to the whole-brain scale, we will identify signatures of switching transitions in resting state BOLD functional connectivity and show that this switching
can be accounted for by mean-field computational models of large-scale cortical networks, provided that the repertoire of possible dynamical states is maximized by operating at a suitable (slightly subcritical) working point.

We will conclude discussing the biomarking potential of metrics of Functional Connectivity Dynamics and presenting promising applications to functional imaging datasets in human aging.


Published references:
Kirst C, Timme M, Battaglia D (2016) Dynamic information routing in complex networks. Nat Comms 7:11061.
Battaglia D, Witt A, Wolf F, Geisel T (2012) Dynamic Effective Connectivity of Inter-Areal Brain Circuits. PLoS Comp Biol 8:e1002438.
5 septembre 2016

Séminaire · invité par Manuel Mercier

Rhythmic facilitation of auditory perception by entrainment 'to implicit and explicit rhythmic cues'

Saskia Haegens
Columbia University Medical Center

Lundi 5 septembre 2016 · 10h Salle de réunion 2eme (Pavillon Baudot), Hôpital Purpan

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2 septembre 2016

Conférence CerCo

Beta oscillations reflect supramodal information during perceptual judgment

Saskia Haegens
Columbia University Medical Center

Vendredi 2 septembre 2016 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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23 juin 2016

Séminaire · invité par Rasa Gulbinate

Midfrontal theta oscillations are a key link between cognitive control and the brain

Mike X Cohen
Netherlands Institute for Neuroscience

Jeudi 23 juin 2016 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Action monitoring helps you overcome your urge to order triple-chocolate ice-cream cake and instead get the fruit platter. The neural computations underlying action monitoring, and how those computations are implemented by neural circuits, are under-explored and largely speculative. We and others discovered and spent the past 8 years characterizing the EEG signature of action monitoring, which comprises theta-band oscillations (~6 Hz) in the medial prefrontal cortex. Looking broadly at this literature leads to two important questions: (1) Does midfrontal theta play a meaningful role in the neural computations underlying action monitoring? (2) What kind of neural microcircuit in the prefrontal cortex might produce midfrontal theta oscillations and associated action monitoring computations? Sadly, these questions remain unanswered, but my research group is now poised to provide at least some initial sketches of the answer. In this talk, I will provide a bird's-eye overview of this literature, what I think are the important future directions and how we can get there, and why I think theta oscillations are the key bridge between human cognitive control and understanding its neural implementation.
15 juin 2016

Conférence CerCo

2D Cues to 3D Structure Underlie Categorization of Real-world Scenes

Dirk Bernhardt-walther
Department of Psychology, University of Toronto

Mercredi 15 juin 2016 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
http://bwlab.utoronto.ca/people/
10 juin 2016

Séminaire · invité par Vannson Nicolas

Soutenance de thèse. La surdité unilatérale :
approches psychoacoustiques, qualité de vie et neuroimagerie fonctionnelle par IRMf

Vannson Nicolas
CerCo

Vendredi 10 juin 2016 · 13h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
La compréhension dans un milieu social (un bar par exemple) repose sur l'audition binaurale, c?est-à-dire l'écoute naturelle via deux oreilles saines. Toutefois, certaines personnes souffrent d'une perte de l?audition binaurale à la suite d'une surdité unilatérale. Cette atteinte touche une seule des deux oreilles et engendre des déficits psychoacoustiques et comportementaux indéniables. Par ailleurs, la surdité unilatérale induit également une réorganisation centrale qui se manifeste par une augmentation de l?activation corticale ipsilatérale à l?oreille saine. Toutefois, aucune étude n?a encore démontré de lien éventuel entre un niveau de réorganisation centrale et un niveau de performances psychoacoustiques. C?est pourquoi, l?objectif de ce travail de thèse a consisté à mesurer le niveau de réorganisation centrale secondaire à une surdité unilatérale et à corréler ce niveau de réorganisation à un niveau de déficit psychoacoustique. Les résultats démontrent qu?une surdité unilatérale induit une réorganisation corticale qui s?accompagne d?une baisse significative des performances psychoacoustiques. Ce travail souligne donc la nécessite de réhabiliter une personne souffrant d?une perte de l?audition binaurale.
31 mai 2016

Conférence CerCo

Memory and neural plasticity:
What we can learn from synaesthesia research

Nicolas Rothen
Institute of Psychology and Center for Cognition, Learning and Memory, University of Bern, Switzerland

Mardi 31 mai 2016 · 16h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The talk consists of three parts. In the first part, I will briefly define synaesthesia and introduce some associated characteristics. In the second and major part, I will present empirical evidence that synaesthesia is associated with enhanced memory performance in comparison to individuals who do not have synaesthesia. In the third part, I will present empirical evidence that the characteristics associated with genuine synaesthesia can be acquired by means of an extensive training procedure. I will conclude that synaesthesia studies are a useful tool to advance our understanding of higher cognitive functions (e.g., memory processes) and neural plasticity (e.g., training studies).
31 mai 2016

Séminaire · invité par Marie Margeride Garnier

Soutenance de thèse / PHD Defence ; La synesthésie chez l'enfant :
Prévalence, aspect développementaux et cognitifs

Marie Margeride Garnier
Laboratoires CLLE-LTC et CerCo, Université de Toulouse

Mardi 31 mai 2016 · 10h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Les synesthètes ont la particularité lors de la présence de certains stimuli (e.g. une lettre), d?associer une expérience supplémentaire (e.g. une couleur). L?objectif de ma thèse est alors de mieux comprendre le développement de la synesthésie à travers trois types : Graphème-Couleur (GC), Graphème-Personnalité (OLP) et représentation des nombres dans l'espace (SS). Si la synesthésie GC a déjà été étudiée chez l?enfant, et seulement dans la population anglo-saxonne, les deux autres n?ont jamais fait l?objet d?étude développementale auparavant.
Les productions graphiques de 797 enfants de GS, CP, et CE1 ont été recueillies (2 sessions, 2 à 3 semaines d?écart). Nous n?avons pu mesurer qu?une forme simple de la OLP, l?association d?un genre aux lettres et aux chiffres.Pour tester l?hypothèse d?un continuum entre les synesthètes et la population générale, nous avons aussi étudié les associations d?enfants non synesthètes.
Nous avons mis en avant les difficultés méthodologiques de l?étude de la synesthésie chez les enfants entre 5 et 8 ans. Nos résultats ne nous permettent pas d?attester de l?existence de la synesthésie dans cette tranche d?âge. Mais on remarque une augmentation du nombre de synesthètes potentiels par niveau scolaire, et un niveau de constance bas de leurs associations par rapport à ce qui est observé chez l?adulte. Comme les enfants connaissent bien les lettres et les nombres, du moins en CE1, on peut penser que ces synesthésies ne soient pas liées à l?apprentissage de l?inducteur. Mais elles pourraient se mettre en place lors des apprentissages plus complexes ou avec le développement de l?imagerie mentale et de la mémoire associative.
24 mai 2016

Séminaire · invité par Simon Thorpe

Implementing Bio-inspired Spiking Deep Neural Networks

Olivier Bichler
CEA List, Saclay

Mardi 24 mai 2016 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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28 avril 2016

Conférence CerCo

A Vocal Brain:
Cerebral Processing of Voice Information

Pascal Belin
Centre Européen de Recherche en Imagerie Médicale & Institut des Neurosciences de la Timone. Marseille

Jeudi 28 avril 2016 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The human voice carries speech but also a wealth of socially-relevant, speaker-related information. Listeners routinely perceive precious information on the speaker?s identity (gender, age), affective state (happy, scared), as well as more subtle cues on perceived personality traits (attractiveness, dominance, etc.), strongly influencing social interactions. Using voice psychoacoustics and neuroimaging techniques, we examine the cerebral processing of person-related information in perceptual and neural voice representations. Results indicate a cerebral architecture of voice cognition sharing many similarities with the cerebral organization of face processing, with the main types of information in voices (identity, affect, speech) processed in interacting, but partly dissociable functional pathways.
27 avril 2016

Séminaire · invité par Edward Collet

Soutenance de Thèse / Phd Defence

Edward Collett
Strategies of Auditory Categorisation in Cochlear Implant Users and Normal Hearing Listeners

Mercredi 27 avril 2016 · 13h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Auditory categorisation involves the grouping of acoustic events along one or more shared perceptual dimensions which can relate to both semantic and physical attributes. Whilst previous work has established certain categories (for example living and non-living, mechanical, natural and sounds) and identified the importance of perceptions concerning the sound producing event (object and action) the research domain is still to be fully understood.
The process of categorising sounds also involves both high level cognitive processes and low-level perceptual encoding of the acoustical signal, both of which are affected by the use of a cochlear implant (CI), such that auditory abilities are often severely diminished in comparison to normal hearing listeners (NHL).Existing studies have shown that CI users perform better at identifying the auditory category compared to a specific sound, however these studies have used a fixed and limited number of categories. A Free-Sorting-Task (FST) is used in the current work to test categorisation performance in a more real-world manner, whereby participants may categorise sounds however they choose. Subsequent analysis consisted of Multiple Correspondence Analysis (MCA) and HCPC to determine the categories and strategies used by participants.
The FST was used to determine how CI users duration of implantation (from 0 to more than 14 months) would affect the categorisation of everyday sounds. Results showed that experienced listeners performed similarly to NHL, separating vocal, musical and environmental sounds. Experienced CI also showed ability to separate a set of vocal sounds by emotional content.
NHL were also tested with only environmental sounds and demonstrated categorisation based on the sound producing object or action even when sounds were vocoded with only 4 channels. However context information was not strongly perceived and did not aid the identification of sounds.
The presented work adds important research to the study of auditory categorisation and is in agreement with previous works. Results of CI users show the potential of using the FST for further research and contains the possibility of using categorical perception as a useful tool in rehabilitation and assessment techniques.
11 avril 2016

Conférence CerCo

Cortical and subcortical neuronal correlates to spatial attention

Fabrice Arcizet
Laboratory of Sensorimotor Research National Eye Institute. National Eye Institute. Bethesda

Lundi 11 avril 2016 · 11 he Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Spatial attention is commonly described as important for managing the limited resources available in sensory areas of the neocortex. In this talk, I will present data from cortex and basal ganglia demonstrating that mechanisms downstream of sensory processing could be involved in control of attention. First, we tested neuronal activity in cortical areas LIP and V4 when animals were required to divide their attention among multiple items in a display. We found that neuronal responses in LIP showed correlates of attention, but sensory area V4 did not, suggesting that mechanisms downstream from cortical sensory areas are also involved in the control of attention. Second, we investigated how neuronal activity in the caudate nucleus, one of the major input structures of the basal ganglia, is modulated by different task events during the performance of a change detection task. Neurons in the caudate nucleus also exhibited correlates of attention ? their activity was related to factors such as cue location and response choice. In addition, the activity of many caudate neurons was selective for particular combinations of sensory events and motor responses, consistent with establishing a link between sensory signals and action selection. Together, these results illustrate that the mechanisms for spatial attention are not restricted to cortical areas, but also include circuits centered on the basal ganglia linking evaluation of sensory information and motor decisions.
7 avril 2016

Conférence CerCo

Adaptive gain control during perceptual decision-making in monkeys and humans

Chris Summerfield: Cancelled!!!
University of Oxford

Jeudi 7 avril 2016 · 10h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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6 avril 2016

Séminaire · invité par Lionel Nowak

Inhibitory connectivity defines the realm of excitatory plasticity

Gianluigi Mongillo
Center for Neurophysics, Physiology and Pathology. CNRS UMR8119. Paris Descartes University

Mercredi 6 avril 2016 · 14h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
The neocortical network is largely excitatory as most neurons and most synapses are excitatory. Accordingly, it is widely held that cortical dynamics, and computations, are primarily determined by the pattern of excitatory synaptic connections. However, there is strong experimental evidence that excitatory connectivity is constantly re-organizing, even in the absence of explicit learning. This raises the question of how functionality is maintained over time in volatile networks. Here, we quantified spontaneous synaptic re-organization by chronically imaging thousands of dendritic spines in the mouse auditory cortex, and investigated its consequences in a balanced network model of a cortical region. Surprisingly, we found that the firing rates of individual neurons are stably maintained despite massive excitatory plasticity. By contrast, they are exquisitely sensitive to changes in the pattern of inhibitory synaptic connections. We show that this is a direct consequence of the different distributions of firing rates of the excitatory and inhibitory neurons. Computationally, these results indicate that inhibitory plasticity ? but not excitatory plasticity ? is both necessary and sufficient for large scale changes in the patterns of network's spiking activity. Taken together, our findings show that inhibition can maintain functional stability in a volatile network by bounding the impact of excitatory synaptic re-organization.
5 avril 2016

Conférence CerCo

Cognitive Adventures of Single Neurons in the Human Medial Temporal Lobe

Florian Mormann
Department of Epileptology, University of Bonn

Mardi 5 avril 2016 · 11h Salle de conférence, Hôpital Purpan

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4 avril 2016

Séminaire · invité par Robin Baurès

Smart digital camera based on spatial pre-processing filtering and spike generation

Michel Paindavoine
Laboratoire d\\\\\\\'Etude de l\\\\\\\'Apprentissage et du Développement

Lundi 4 avril 2016 · 15h30 Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Smart vision circuits are expected to extract high-level information from visual scenes. The main focus of these intelligent retinas is not to provide the highest image quality, but high level information on the image, and be a building block for object recognition with many applications in areas such as robotics, security, automotive, home automation,? Since these applications require a very high bandwidth and a dense and highly efficient data processing technology, leading to use a high level of parallelism, a close integration of the processing capabilities together with the detection components is needed. Classical approaches use complex algorithms that are difficult to implement using parallel implementations. Such approaches invariably lead to high processing latencies and high power consumption.
In contrast, biological vision systems acquire and process information continuously in time. Biological retinas send image information to the visual cortex using action potentials, also named spikes. These spikes are events, and carry information through their timing and frequency. When the integration over time of the illumination level of a certain pixel reaches a threshold, the pixel sends a spike. Very active pixels send more spikes, and spikes propagate through the processing chain as soon as they are generated without waiting for the whole image to be processed. Bio-inspired spikes-based systems have been already proposed (see for example Culurciello, Etienne-Cummings, Boahen, ?A biomorphic digital image sensor?. IEEE J. Solid-State Circuits, 2003; Lichtsteiner P, Posch C, Delbruck T; ? A 128x128 120 db 15 ?s latency asynchronous temporal contrast vision sensor. IEEE J. Solid-State Circuits, 2008). These systems have shown very good performances due to their fast sensing capability, reduced information throughput and small per-event power consumption. However all these systems are based on local variation in light intensity of pixels and do not take into account the variations in brightness in the vicinity of a pixel having undergone spatial filtering. Indeed, as described in Thorpe S et al, ?Suggestions for a biologically inspired spiking retina using order-based coding?, IEEE ISCAS 2010, it?s more efficient in words of object recongition capability to consider spike generation from pixels having undergone local filtering.
In this context, we have implemented in the smart camera from GlobalSensing Technology (http://gsensing.eu/products/smart-neurocam) a new spikes generation algorithm. This smart camera is based on a digital CMOS image sensor (Aptina MT9V024) coupled with an FPGA (Xilinx Spartan 6). Therefore, our system operates at discrete time and in order to get closer to a process information continuously in time, we accelerated the speed of the sensor using a binning approach. Thus, the images generated by the sensor are in a format of 188x120 pixels @ 240fps and can be processed with the FPGA according to a dataflow process.
In this way we have implemented different spatial filters such as Laplacian filters or Gabor filters. The generation of spikes can thus be performed in real time (@240fps) by considering the luminance variation in output of the spatial filtering.
The validation of our system has been successfully conducted on a moving vehicle detection application.
31 mars 2016

Conférence CerCo

What can we learn on cortical waves with neural fields models? Que peut-on apprendre sur les ondes corticales à l?aide de modèles de champs neuronaux?

Grégory Faye, Cnrs Researcher
Institut de Mathématiques de Toulouse

Jeudi 31 mars 2016 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
In this talk, we are interested in the modeling and the study of various types of cortical waves. We will mainly focus on two types of waves: fronts and pulses. Our approach will rely on neural fields equations. Such equations were derived in the 70s by Wilson & Cowan and describe the mean cortical activity of populations of neurons. To simplify the analysis, we assume that the waves under study are unidimensional in the sense that they are constant along the orthogonal direction of propagation. A mathematical analysis of these equations will help understand and explain how the neuronal connectivity, propagation delays, heterogeneities shape and modulate cortical waves.
22 mars 2016

Séminaire · invité par Tim Masquelier

Invariant Object Recognition in Humans and Deep Networks

Saeed Reza Kheradpisheh
University of Tehran

Mardi 22 mars 2016 · 11h Salle de conférence (Pavillon Baudot), Hôpital Purpan

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Résumé
Deep convolutional neural networks (DCNNs) have attracted much attention recently, and have shown to be able to recognize thousands of object categories in natural image databases. Their architecture is somewhat similar to that of the human visual system. Yet it is unknown whether DCNNs match human performance at the task of view-invariant object recognition, whether they make similar errors and use similar representations for this task, and whether the answers depend on the magnitude of the viewpoint variations. To investigate these issues, we benchmarked eight state-of-the-art DCNNs, the HMAX model, and a baseline shallow model and compared their results to those of humans with backward masking. Our results indicate that DCNNs can reach human feed-forward vision accuracy, with similar error distributions. In addition, our results show that deeper networks are more accurate and more human-like, but only in the presence of large variations.

Some of our previous modeling work indicated that spike timing-dependent plasticity can lead to robust invariant object recognition, even in relatively shallow spiking neural networks. Encouraged by these results, we now want to investigate if the rule is also beneficial to deeper spiking convolutional neural networks.
5 février 2016

Conférence CerCo

Thesis defense:
Temporal and spatial flexibility of visual object neural representations

Mehdi Senoussi
CerCo

Vendredi 5 février 2016 · 13h30 Salle de conférence, Hôpital Purpan

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5 février 2016

Conférence CerCo

How do prior expectations change perception?

Floris De Lange
Donders Institute

Vendredi 5 février 2016 · 10h30 Salle de conférence, Hôpital Purpan

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Résumé
Although there is ample behavioral evidence for the predictive nature of perception, the incorporation of prior expectations in the neural computations underlying perception is still poorly understood.

In my lecture, I will review recent work on how prior expectations about the sensory world change the neural computations that give rise to perception. Drawing on human fMRI and MEG data, I will show that prior expectations generate 'virtual sensations' in early sensory circuits, which may serve to sharpen bottom-up sensory inputs.
2015 32
10 décembre 2015

Conférence CerCo

Representation sémantique des objets sonores

Stéphanie Clarke
Université de Lausanne

Jeudi 10 décembre 2015 · 11h Salle de conférence, Hôpital Purpan

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9 décembre 2015

Conférence CerCo

Oscillatory processes in perception

1-day Conference
Centre de Recherche Cerveau et Cognition

Mercredi 9 décembre 2015 · 9h Salle de conférence, Hôpital Purpan

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Résumé
1-day conference (~9-16.30h) on oscillatory processes in perception.
Plenary speakers in the morning are: Anne-Lise Giraud, Peter Lakatos, Ole Jensen.
The afternoon sessions consist of PhD candidates and Post-Docs presenting their own work.
Attendance of the conference (including lunch) is free, but registration is necessary (zoefel@cerco.ups-tlse.fr).
Program available on request.
8 décembre 2015

Conférence CerCo

Thesis defense:
Phase entrainment and Perceptual Cycles in Audition and Vision

Benedikt Zoefel
Centre de Recherche Cerveau et Cognition

Mardi 8 décembre 2015 · 14h Salle de conférence, Hôpital Purpan

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Résumé
Recent research indicates fundamental differences between the auditory and visual systems: Whereas the visual system seems to sample its environment, cycling between ?snapshots? at discrete moments in time (creating perceptual cycles), most attempts at discovering discrete perception in the auditory system failed. Here, we show in two psychophysical experiments that subsampling the very input to the visual and auditory systems is indeed more disruptive for audition; however, the existence of perceptual cycles in the auditory system is possible if they operate on a relatively high level of auditory processing. Moreover, we suggest that the auditory system, due to the rapidly fluctuating nature of its input, might rely to a particularly strong degree on phase entrainment, the alignment between neural activity and the rhythmic structure of its input: By using the low and high excitability phases of neural oscillations, the auditory system might actively control the timing of its ?snapshots? and thereby amplify relevant information whereas irrelevant events are suppressed. Not only do our results suggest that the oscillatory phase has important consequences on how simultaneous auditory inputs are perceived; additionally, we can show that phase entrainment to speech sound does entail an active high-level mechanism. We do so by using specifically constructed speech/noise sounds in which fluctuations in low-level features (amplitude and spectral content) of speech have been removed, but intelligibility and high-level features (including, but not restricted to phonetic information) have been conserved. We demonstrate, in several experiments, that the auditory system can entrain to these stimuli, as both perception (the detection of a click embedded in the speech/noise stimuli) and neural oscillations (measured with electroencephalography, EEG, and in intracranial recordings in primary auditory cortex of the monkey) follow the conserved ?high-level? rhythm of speech. Taken together, the results presented here suggest that, not only in vision, but also in audition, neural oscillations are an important tool for the discretization and processing of the brain?s input. However, there seem to be fundamental differences between the two systems: In contrast to the visual system, it is critical for the auditory system to adapt (via phase entrainment) to its environment, and input subsampling is done most likely on a hierarchically high level of stimulus processing.
2 décembre 2015

Conférence CerCo

Est-ce que la stimulation du nerf vague peut influencer la mémoire ?

Michelle Gué
Université Paul Sabatier

Mercredi 2 décembre 2015 · 14h Salle de conférence, Hôpital Purpan

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Résumé
Présentation de Michelle Gué en vue d'une intégration au CerCo.
30 novembre 2015

Conférence CerCo

An oscillatory perspective on multisensory interaction

Manuel Mercier
CerCo

Lundi 30 novembre 2015 · 11h Salle de conférence, Hôpital Purpan

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26 novembre 2015

Conférence CerCo

Active Efficient Coding

Jochen Triesch
J.W. Goethe University, Frankfurt

Jeudi 26 novembre 2015 · 11h Salle de conférence, Hôpital Purpan

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Résumé
In many biological and artificial sensory systems, perception is an active process that involves movements of the sense organs such as the eyes, ears, or whiskers. These movements must be learned and calibrated. In biological systems this process is occurring autonomously and continuously. The mechanisms underlying such self-calibration are still largely unknown. We have recently proposed a new theoretical framework called Active Efficient Coding (AEC), that tries to explain how this self-calibration may take place. In a nutshell, AEC is a generalization of classic efficient coding theories in sensory neuroscience to active perception involving movements of the sense organs. AEC posits that the self-calibration of various sensorimotor loops results from the brain learning to control the movements of its sense organs to maximize its efficiency of encoding sensory inputs. We show the feasibility of this approach for the autonomous self-calibration active
binocular vision and active motion vision and demonstrate how it can be successfully implemented on a humanoid robot.
20 novembre 2015

Séminaire · invité par Simon Thorpe

The absolute disparity anomaly and the mechanism of relative disparities.

Adrien Chopin
University of California, Berkeley, USA

Vendredi 20 novembre 2015 · 11h Salle de conférence, Hôpital Purpan

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10 novembre 2015

Conférence CerCo

HDR Defense

Chloë Farrer
HDR Defense

Mardi 10 novembre 2015 · 14h30 Salle de conférence, Hôpital Purpan

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5 novembre 2015

Séminaire · invité par Rufin Vanrullen

The neural basis of visual conflict resolution:
Do neurons that detect interocular differences initiate binocular rivalry?

Sucharit Katyal
Engel Vision and Imaging Lab, University of Minnesota

Jeudi 5 novembre 2015 · 11h Salle de conférence, Hôpital Purpan

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Résumé
In individuals with normal binocular vision, the brain combines images from
the two eyes to form a single visual percept. However, there are often
scenarios in the world where the two eyes receive non-corresponding images
that give rise to "interocular conflict." In laboratories, presenting
substantially conflicting images to the two eyes, such as orthogonally
oriented gratings, gives rise to the phenomenon of binocular rivalry where
an individual's percept alternates every few seconds between the two
images. A recently developed computational model suggests that in order for
such striking alternations to arise, early visual cortex makes use of
"opponency" neurons, which compute the difference of the two eyes' inputs,
and inhibit the weaker eye (Said and Heeger, 2013). We conducted a series
of experiments using steady state visually evoked potentials (SSVEPs) and
visual adaptation to investigate, 1) if we can find evidence for neurons
that signal interocular conflict in humans, and if so, 2) what role do they
play in binocular rivalry? We found that certain intermodulation
frequencies of SSVEPs contain a signature of interocular conflict, and that
such conflict detection is critical for the brain in deciding whether to
fuse or rival the two eyes' images.

*Reference*
Said, C. P. & Heeger, D. J. (2013) A Model of Binocular Rivalry and
Cross-orientation Suppression. PLoS Comput Biology 9, e1002991.
23 octobre 2015

Conférence CerCo

Starting Neurotechnology Companies for Fun and Profit

Prof. Max Cynader
Founder of the Brain Research Centre, University of British Columbia, Vancouver, Canada

Vendredi 23 octobre 2015 · 17h Salle de conférence, Hôpital Purpan

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Résumé
This is a special invited conference at the end of the GDR GRAEC workshop on "Veillissement auditifs et troubles associés" organised by the CerCo and the ORL service of Purpan Hospital." The title was changed from the original "Enhancing the Plasticity of the Brain"
20 octobre 2015

Conférence CerCo

How can we study (very) complex systems that we know only (very) little of:
the case of children's learning and development

Paul Van Geert
University of Groningen

Mardi 20 octobre 2015 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Contrary to what the title of this presentation suggests, we know of course an awful lot about children's development. Having been children ourselves we are first-hand witnesses, and children of all possible ages are constantly around us, ready to be studied and observed. On the other hand, there exists a tremendous amount of scientific publications on children's learning, development and education (278 indexed journals). Whereas the first type of knowledge is anecdotal and unorganized ? although rich and highly varied ? the second type of knowledge is to a very great extent determined by a model that treats children's learning and development as a basically linear combination of the effects of many variables, i.e. as some sort of complicated linear system. In my view, it is much more plausible to treat children's learning and development as expressions of complex dynamic systems. What does this stance mean with regard to theory formation and empirical research in the developmental and educational sciences? In this presentation, I will discuss possibilities, opportunities and problems for the study of development and education from the viewpoint of complex dynamic systems (including some thoughts on sports performance and sports education).
19 octobre 2015

Séminaire · invité par Leila Reddy

Recordings from Human V2/V3

Jessy Possel
Netherlands Institute of Neuroscience

Lundi 19 octobre 2015 · 11h Salle de conférence, Hôpital Purpan

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8 octobre 2015

Conférence CerCo

Soutenance de Thèse :
Développement préclinique de sondes fluorées utilisées dans l'imagerie moléculaire des pathologies

Anne-sophie Brun Salabert
INSERM U 825 - CERCO UMR 5549

Jeudi 8 octobre 2015 · 13h30 Salle de conférence, Hôpital Purpan

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Résumé
Résumé :

Les mécanismes physiopathologiques liés aux maladies neurodégénératives restent encore largement méconnus. Deux processus semblent être particulièrement en cause dans les phénomènes de neurodégénerescence : la neurotoxicité par afflux massif de calcium due à une activation excessive des récepteurs NMDA (GluN) et la neurotoxicité par déstabilisation du cytosquelette du neurone par le biais de la phosphorylation anormale de la protéine tau. L?imagerie moléculaire par le biais de la tomographie par émission de positons (TEP) et de radiotraceurs, en étudiant les mécanismes moléculaires in vivo, permet de détecter et quantifier ces phénomènes. Ce travail a eu pour objet d?étudier un dérivé de la mémantine, un antagoniste des GluN se fixant sur un site intra-canal accessible uniquement lorsque ces récepteurs sont activés ce qui en fait donc un vecteur d?imagerie intéressant pour étudier leur activation. Nous avons mis au point la synthèse d?un nouveau radiotraceur dérivé de la mémantine : la [18F]-FNM (Fluoroéthylnormémantine). Il s?agit d?une synthèse par substitution nucléophile d?un groupement tosylate par du [18F], suivie d?une hydrolyse acide. Cette synthèse est reproductible avec un rendement de 10%, son activité spécifique est > 355 GBq/µmol. Chez le rat, le traceur passe la barrière hémato-encéphalique et sa distribution cérébrale est bien corrélée avec la localisation des GluN (r=0.622, p<0.0001). Sa cinétique de fixation (40 minutes) est compatible avec son utilisation en TEP. En ce qui concerne les tauopathies, la protéine tau stabilise l?organisation microtubulaire. Lors d?une phosphorylation anormale, l?interaction avec les microtubules diminue et les protéines tau vont s?accumuler en formant des Paires de Filaments en Hélice (PHF). Nous avons optimisé la radiosynthèse de l? [18F]-AV1451 ciblant la partie 386TDHGAE391 des PHF. Notre rendement de synthèse est de 30% et l?activité spécifique du traceur > 10 GBq/µmol. Nous avons réalisé des autoradiographies sur des coupes de cerveaux atteints de tauopathie et nous avons constaté la capacité du traceur à différencier les coupes saines des coupes malades. La production de cet outil dans notre centre va nous permettre d?étudier la présence de PHF chez le marmouset, un primate particulièrement intéressant dans l?étude du vieillissement. Nous avons donc réalisé la synthèse de deux radiotraceurs innovants : la [18F]-FNM et le [18F]-AV1451, les synthèses sont reproductibles et les rendements compatibles avec des productions de doses en recherche pré-clinique et clinique.
2 octobre 2015

Conférence CerCo

Soutenance de thèse:
Vision périphérique, caractérisation et suppléance de ses fonctions spatiales

Damien Camors
CNRS UMR 5549 - 5505

Vendredi 2 octobre 2015 · 14h Salle de conférence, Hôpital Purpan

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Résumé
Notre champ visuel, c'est-à-dire la portion de l?espace vue par nos yeux, n?est pas homogène. On distingue la vision centrale et la vision périphérique. La vision périphérique possède une acuité plus faible que la vision centrale, mais influe sur les représentations internes que l?on a de l'environnement. L?influence de la vision périphérique sur ces représentations n?est cependant pas bien définie. Durant ma thèse, j?ai montré que la vision périphérique participait aux représentations égocentrées, c'est-à-dire à des représentations centrées sur le corps de l?observateur. J?ai observé par ailleurs que la vision périphérique contribuait à la construction de représentations allocentrées, permettant d?extraire les relations spatiales entre éléments présents dans l?environnement, indépendamment de l?observateur et facilitant la recherche visuelle d?objets. De ces résultats, j?ai élaboré une nouvelle interface tactile qui facilite les recherches visuelles en absence de vision périphérique.
17 septembre 2015

Conférence CerCo

Tracking attention and perception in real-time as a window into covert prefrontal processes

Suliann Ben Hamed
Centre de Neuroscience Cognitive, Lyon

Jeudi 17 septembre 2015 · 11h Salle de conférence, Hôpital Purpan

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Résumé
The prefrontal cortex, including the frontal eye fields, is thought to play an important role in orienting spatial attention and in the suppression of irrelevant distracters during active vision. However, how distracters interfere with sustained attention signals and how attention and interference signals correlate with overt behavior at the single trial level is yet unknown. In a first part of my talk, I will show that spatial attention and perceptual processes can be tracked in real-time from the activity of bilateral prefrontal dense neuronal recordings, performed while two macaque monkeys are engaged in a cued attention orientation task, in the presence of distractors. I will also show that error miss and false alarm trials arise due to a misencoding of attention orientation correlating with an initial misencoding of the cue location. On these miss and false alarm trials, attention-related representations are more susceptible to distracter interference and are best described by a high noise-correlation state across the recorded neuronal population. Last I will show that the specific distinguishing feature between false alarms and misses is the fact that false alarm trials arise when the distracter happens to be presented at the location at which attention is misoriented. In a second part of my talk I will use this real-time tracking of attention for two distinct neurofeedback applications. The first application is a basic neuroscience application and involves investigating the effect of distractors on overt behavior as a function of its distance to the actual endogenous position of attention, independently of task instructions. The second application paves the way for cognitive brain machine interfaces and involves enhancing prefrontal attentional processes based on positive reinforcement procedures guided by the real-time decoding of attention.
14 septembre 2015

Séminaire · invité par Rufin Vanrullen

Voluntary saccadic eye movements ride the attentional rhythm

Hinze Hogendoorn
Utrecht University

Lundi 14 septembre 2015 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Visual perception seems continuous, but recent evidence suggests that the underlying perceptual mechanisms are in fact periodic ? particularly visual attention. Because visual attention is closely linked to the preparation of saccadic eye movements, the question arises how periodic attentional processes interact with the preparation and execution of voluntary saccades. In two experiments, human observers made voluntary saccades between two placeholders, monitoring each one for the presentation of a threshold-level target. Detection performance was evaluated as a function of latency with respect to saccade landing. The time-course of detection performance revealed oscillations at around 4 Hz both before the saccade at the saccade origin, and after the saccade at the saccade destination. Furthermore, oscillations before and after the saccade were in phase, meaning that the saccade did not disrupt or reset the ongoing attentional rhythm. Instead, it seems that voluntary saccades are executed as part of an ongoing attentional rhythm, with the eyes in flight during the troughs of the attentional wave. This finding for the first time demonstrates that periodic attentional mechanisms affect not only perception but also overt motor behaviour.
11 septembre 2015

Conférence CerCo

Audiovisual integration in time-to-collision judgments

Daniel Oberfeld
Université Johannes Gutenberg, Mainz, Allemagne

Vendredi 11 septembre 2015 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Judging when a moving object will arrive at a designated position in space is
crucial in traffic and in sports. Previous studies of time-to-collision (TTC)
estimates focused on the effectiveness of visual TTC information in the optical
expansion pattern (e.g., visual tau). Fewer studies measured the integration of
auditory and visual TTC information. The latter studies did not systematically
investigate the use of "heuristic" cues such as final optical size, and in general
did not provide compelling information about the relative weighting of different
auditory and visual cues. I will present a study in which participants judged the
TTC of an approaching object presented in the visual or auditory modality, or both
concurrently. A psychophysical reverse correlation approach was used to estimate the
influence of auditory and visual cues on TTC estimates. Multiple regression analyses
showed that TTC estimates were based on both auditory and visual information, and
that visual information was weighted more heavily. In the auditory modality, the TTC
estimates were more strongly influenced by the final sound pressure level than by
the actual auditory TTC. Thus, we found an analogy of the well-documented effect of
final optical size on visual TTC estimates.
As a first step towards understanding the psychoacoustic bases of auditory TTC
judgments, we measured the detection of gradual changes in level within pure tones
of either 500 ms or 2000 ms duration. The sensitivity for detecting a gradual
increase in level corresponding to a looming sound source was compared to control
conditions such as a receding sound source. Only for the short sounds a weak,
non-significant advantage for looming sounds was found, different from what is
suggested by claims that "looming is special". However, for the short sounds the
correlation between sensitivity in the looming and the receding condition was weak,
suggesting that different strategies or mechanisms might be involved. The
sensitivity increased with sound duration, which indicates that the rate of change
in level does not determine the detectability of gradual level changes.
3 septembre 2015

Séminaire · invité par Benedikt Zoefel

Effects of sensorineural hearing loss on cortical temporal processing

Rebecca Millman
York Neuroimaging Centre

Jeudi 3 septembre 2015 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Background noise can interfere with, or mask, our ability to understand speech. When temporal fluctuations are imposed on noise maskers, normal-hearing (NH) listeners may benefit more than hearing-impaired listeners with a sensorineural hearing loss (SNHL) from speech masking release, i.e. the ability to ?listen in the dips? of modulated noise maskers. Factors beyond reduced audibility in SNHL listeners, including both perceptual and cognitive mechanisms, contribute towards the ability to benefit from speech masking release. Impaired supra-threshold temporal processing may reduce the ability of SNHL listeners to benefit from speech masking release (e.g. Bacon et al., 1998; Moore et al., 1999). SNHL enhances the neural coding of the temporal envelope of sounds (e.g. Moore et al., 1996; Kale & Heinz, 2010). This enhanced temporal coding is thought to have a detrimental effect on the ability of hearing-impaired listeners to understand speech in the presence of modulated maskers. We used magnetoencephalography (MEG) to test the hypothesis that cortical entrainment to modulated noise is enhanced in SNHL listeners who benefit less from speech masking release than NH listeners. In accordance with the Asymmetric Sampling in Time model (e.g. Poeppel, 2003) cortical entrainment to a 2-Hz square-wave-gated noise was lateralised to areas in right auditory cortex within both listener groups. Cortical entrainment was enhanced in poor "dip listeners" (SNHL), when compared with good "dip listeners" (NH); however, this enhancement was more evident in right auditory cortex. Our results demonstrate a degree of functional lateralisation in cortical entrainment to modulated sounds in poor "dip listeners" which may have important translational implications for auditory prostheses.
2 septembre 2015

Conférence CerCo

Properties of the the theta-gamma code and its role in working memory

John Lisman
Brandeis University

Mercredi 2 septembre 2015 · 11h Salle de conférence, Hôpital Purpan

Affiche
7 juillet 2015

Séminaire · invité par Simon Thorpe

Role of Parieto-Frontal Cortices in the Control of Attention and Decision Making

Guilhem Ibos
Dept of Neurobiology, University of Chicago, USA

Mardi 7 juillet 2015 · 14h Salle de conférence, Hôpital Purpan

Affiche
16 juin 2015

Conférence CerCo

How to drive a perceptual Ferrari:
goal-oriented behaviour in a visual system reorganised by early deafness

Prof. Francesco Pavani.
Center for Mind/Brain Sciences (CIMeC) University of Trento, Italy

Mardi 16 juin 2015 · 14h Salle de conférence, Hôpital Purpan

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Résumé
In the last decades research on the effects of early deafness in humans have documented changes in visual processing, involving the intact visual cortices as well as the deafferented auditory cortices. Behaviourally, deaf people proved particularly sensitive to transients in the visual scene, particularly when they occur towards the periphery of the visual field. To what extent these neural and behavioural changes lead to visual dominance and may limit goal-oriented behaviour in deaf people remained largely unexplored. In this talk, I will present recent evidence from my group addressing the ability of early deaf adults to achieve a balance between bottom-up and top-down mechanisms of selective attention. Furthermore, I will present data on the changes of this attentional balance during development. Overall, results show a remarkable degree of top-down control in deaf adults, that can favour goal-oriented behaviour even within a perceptual system substantially changed by auditory-deprivation.
29 mai 2015

Conférence CerCo

Functional and neurophysiological underpinnings of action control

Florian Waszak
Laboratoire Psychologie de la Perception, Universite Paris Descartes

Vendredi 29 mai 2015 · 11h Salle de conférence, Hôpital Purpan

Affiche
16 avril 2015

Séminaire · invité par Simon Thorpe

Auditory noise:
Who learns it and what do they learn?

Dr. Trevor Agus
Sonic Arts Research Centre, Queen\'s University Belfast, UK

Jeudi 16 avril 2015 · 14h Salle de conférence, Hôpital Purpan

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2 avril 2015

Conférence CerCo

A parallel behavioral approach of odor episodic memory in humans and rodent

Nadine Ravel
Centre de recherche en neurosciences de Lyon

Jeudi 2 avril 2015 · 11h Salle de conférence, Hôpital Purpan

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Résumé
A parallel behavioral approach of odor episodic memory in humans and rodents
Our group developed a novel framework and paradigm that provides means to quantitatively evaluate the ability of rats to form and recollect a combined knowledge of What happened, Where and When/in Which context (referred to as episodic-like memory) after limited encounter of specific episodes in a situation as close as possible to a paradigm we recently developed to study episodic memory in humans.
In a first part, I will present the two protocols in parallel insisting both on their proximity and divergence. In a second part, I will more focus on the results obtained in rodents. Finally, I will try to discuss some of the questions we would like to address in parallel taking advantage of what is possible to do in each model.
2 mars 2015

Conférence CerCo

The interaction between visual shape and category representations in the human brain

Hans Op De Beeck
Laboratory of Biological Psychology - KU Leuven, Belgium

Lundi 2 mars 2015 · 14h Salle de conférence, Hôpital Purpan

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Résumé
Many studies have suggested that the ventral occipitotemporal (VOT) pathway in the human visual cortex is characterized by strong category selectivity for several categorical divisions, including animate versus inanimate and faces versus other body parts versus objects. However, the notion of category selectivity has been criticized: recent studies have suggested that this category selectivity might largely or even completely be explained by selectivity for more basic visual dimensions such as visual shape. In this context I will focus upon the results from a human fMRI study with a new stimulus set in which we independently manipulated category membership and visual shape. Visual shape was an important determinant of the spatial distribution of responses in VOT. In further detail, there was a higher explanatory power of behaviorally assessed shape similarity compared to more low-level measures of shape similarity. In addition, however, category selectivity was also prominently present in VOT and could not be explained by selectivity for any visual dimension such as shape. This category selectivity in the ventral pathway was dominated by the superordinate animate versus inanimate distinction. We also observed category selectivity in the dorsal pathway, but this selectivity was dominated by another superordinate distinction, between action (e.g., tools) and non-action (e.g., fruit) categories of objects. In sum, shape-invariant superordinate category selectivity exists in both the ventral and dorsal visual system of the human brain. It remains to be seen whether such category selectivity also exists in the brains of other mammals.
27 février 2015

Séminaire · invité par Echarp Committee

Four decades of neuroeconomics - a personal view

Simon Thorpe
CerCo

Vendredi 27 février 2015 · 11h Salle de conférence, Hôpital Purpan

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Résumé
This is the presentation that I was supposed to give at the ECHARP meeting but that was cancelled

When I started my thesis with Edmund Rolls in Oxford in 1977, my job was to try and discover how neurons in the monkey lateral hypothalamus could respond selectively to the sight of food, as well as to arbitrary visual stimuli which meant that food was available. Those neurons also have the property of only responding if he monkey was hungry. Much of my career has been following up these basic questions. How do we learn to recognize new visual and auditory stimuli? How we make decisions about them? How do we categorize things? My overall conclusion is that much of the brains sensory processing mechanisms don?t actually care whether a particular stimulus is rewarded or punished - they care more about how often they occur. However, beyond the visual system, there are separate mechanisms in other brain areas whose job is to determine whether a particular object is good or bad. I suspect that these questions are probably quite central to the field of Neuroeconomics.
12 février 2015

Conférence CerCo

Spike-based computing and learning in brains, machines, and visual systems in particular.

Tim Masquelier
Neurobiology of adaptative processes

Jeudi 12 février 2015 · 14h Salle de conférence, Hôpital Purpan

Affiche
3 février 2015

Conférence CerCo

Cerebral cartography using MEG, SEEG and fMRI:
methodological considerations

Christian Bénar
Institut de Neurosciences des systèmes, Marseille

Mardi 3 février 2015 · 11h Salle de conférence, Hôpital Purpan

Affiche
29 janvier 2015

Conférence CerCo

Neural Mechanisms of Object Recognition

Prof. Max Riesenhuber
Lab for Computational Cognitive Neuroscience, Georgetown University, Washington DC, USA

Jeudi 29 janvier 2015 · 14h Salle de conférence, Hôpital Purpan

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22 janvier 2015

Conférence CerCo

Working Memory Functioning and Development through the Time-Based Resource-Sharing Model

Valérie Camos
University of Fribourg - Switzerland

Jeudi 22 janvier 2015 · 14h Salle de conférence, Hôpital Purpan

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Résumé
This talk will present the Time-Based Resource-Sharing model of working memory. In a multi-level cognitive architecture, a central system, conceived as a self-regulated executive loop involving an episodic buffer and a production system, integrates information from peripheral domain-specific buffers and long-term memory. The executive loop is responsible for constructing working memory representations, for maintaining these representations in the face of decay and interference, and for goal-directed processing by triggering executive functions that modify the content of these representations. Apart from a phonological loop able to maintain a limited amount of verbal information through verbal rehearsal, peripheral buffers are conceived of as passive sensory memories with no specific mechanisms of maintenance. Assuming a sequential functioning of the executive loop and the temporal decay of working memory representations, the theory makes a series of predictions about the time-related effect of processing on concurrent maintenance and the postponement of processing by maintenance activities. This talk will review empirical findings in young adults supporting these predictions as well as studies in children, which shed light on factors of working memory development.
15 janvier 2015

Séminaire · invité par Florence Rémy

Que peuvent apporter les neurosciences à la sécurité aérienne?

Mickaël Causse
ISAE, Toulouse

Jeudi 15 janvier 2015 · 11h Salle de conférence, Hôpital Purpan

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7 janvier 2015

Conférence CerCo

Why most published results are false in psychology and neuroscience. Launching the CerCo guidelines for data analysis and statistics usage.

Jean-michel Hupé
CerCo, Université de Toulouse & CNRS

Mercredi 7 janvier 2015 · 14h Salle de conférence, Hôpital Purpan

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Résumé
For decades we have been teaching students Null Hypothesis Significance Tests (NHST) statistics to analyze their data. These tools have yet been criticized since their inception (Meehl 1967, Philosophy of Science 34), because they are only appropriate for taking decisions related to a Null hypothesis (like in manufacturing), not for making inferences about behavioral and neuronal processes (Kline, APA Books 2004). But the times seem ripe for a radical change. In neuroscience, Ioannidis and colleagues revealed that most published studies were severely underpowered (Button et al. 2013, Nature Reviews Neuroscience 14) and, therefore, basically useless. Following Psychological Science that now embraces the 'New Statistics' defended by Cumming (2013, Psychological Science 25), I propose that CerCo encourages our community to publish Confidence Intervals (CI) of effect sizes instead of p-values. Such a small change of practice may foster revolutionary changes in the sociology of our science. At p = 0.05 the 95% CI of the effect size includes zero. The mathematics is the same but the story based upon one or the other presentation differs a lot. In many studies, CIs are often 'embarrassingly large' (Cohen 1994, American Psychologist 49) and, if shown, would have prevented publication. Precision is what we should strive for, not ill-named statistical 'significance'. Precise inference or estimation may often require much more data, and therefore, fewer publications. On the other hand, insisting on precision erases the difference between formerly called 'null' and 'significant' results, and should help fighting against publication biases, file-drawers problems and even fraud. In 1998, Robert Matthews had written in the Sunday Telegraph: « The plain fact is that 70 years ago Ronald Fisher gave scientists a mathematical machine for turning baloney into breakthroughs, and flukes into funding. It is time to pull the plug. » Shifting from p-values to CIs is however challenging for complex data like EEG and MRI. I shall present suggestions for MRI results.
2014 24
12 novembre 2014

Conférence CerCo

Is stereo vision optimized for the natural environment?

Marty Banks
U C Berkeley Vision Science

Mercredi 12 novembre 2014 · 11h Salle de conférence, Hôpital Purpan

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5 novembre 2014

Conférence CerCo

Dynamic patterns across scales:
a phenomenological approach to (human) movement

Raoul Huys
Institut de Neurosciences des Systèmes, Inserm UMR1106, Aix-Marseille Université

Mercredi 5 novembre 2014 · 14h Salle de conférence, Hôpital Purpan

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21 octobre 2014

Conférence CerCo

Langage, Motricité, Attention Spatiale, Cognition :
ce que nous apporte la chirurgie éveillée

Franck-emmanuel Roux
Service Neurochirurgie Hôpital Purpan

Mardi 21 octobre 2014 · 14h Centre d\'Enseignement et de Congrès Pierre-Paul R, Hôpital Purpan

Affiche
17 octobre 2014

Conférence CerCo

Mémoire et imagerie multi-modale

Gaël Chételat
U1077, Caen

Vendredi 17 octobre 2014 · 14h Salle de conférence, Hôpital Purpan

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14 octobre 2014

Conférence CerCo

Elementary time disturbances in schizophrenia:
impairment at looking forward? Causes and consequences.

Anne Giersch
INSERM U1114, Dept of Psychiatry, University Hospital of Strasbourg

Mardi 14 octobre 2014 · 11h Amphi du Centre d\'enseignement et de Congrès (CEC, Hôpital Purpan

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Résumé
At a clinical level patients with schizophrenia display a disturbed sense of time continuity. Experimentally, they are impaired in duration judgments, but also in discriminating between simultaneous and asynchronous events. However, our recent studies show that a judgment of simultaneity does not mean that stimuli are processed as co-temporal, and we explored these implicit mechanisms.
We showed that subjects distinguish stimuli in time at an implicit level even when explicitly judging such stimuli to be synchronous (for asynchronies of 8 to 17 ms, Lalanne et al, Neuropsychologia 2012, Schizophr Bull 2012). Moreover, the implicit responses of patients with schizophrenia differ qualitatively from those observed in controls. It is as if controls always privilege the processing of the last occurred stimulus whereas patients would be stuck with the first one. We will show additional results suggesting the timing impairment in patients is not restricted to time scales <20 ms and to visual perception. Patients indeed have particular difficulties with temporal order judgments.
In controls, elementary predictive mechanisms would allow anticipation of upcoming events, whereas such mechanisms would be impaired in patients with schizophrenia, possibly underlying their disturbed sense of time continuity, and their impairment at looking forward in time. Possible consequences on their perception of the outer world will be discussed.

Co-authors: Mitsouko van Assche, Laurence Lalanne
10 octobre 2014

Séminaire · invité par Rufin Vanrullen

Highly skilled but made redundant ? The transient role of mouse visual cortex in visually guided behaviour

Martha Havenith
Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, The Netherlands

Vendredi 10 octobre 2014 · 14h30 Salle de conférence, Hôpital Purpan

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8 octobre 2014

Conférence CerCo

How good Gestalt determines low level vision

Prof. Michael Herzog
EPFL, Switzerland

Mercredi 8 octobre 2014 · 11h Salle de conférence, Hôpital Purpan

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Résumé
In classical models of vision, vision proceeds in a hierarchical fashion, from low-level analysis (edges and lines) to figural processing (shapes and objects). Low-level processing determines high-level processing. Here, we show that, to the contrary, shape processing determines basic visual processing. For example, we presented a vernier stimulus and asked observers to indicate its offset direction. Performance strongly deteriorated when the vernier was surrounded by a square, in line with most models of vision. Surprisingly, performance improved when more squares were added. This improvement of performance can hardly be explained by classical models of vision, which predict a further deterioration of performance. We propose that shape interactions precede low-level processing in a recurrent fashion. Using high density EEG and trans-cranial magnetic stimulation (TMS), we show how good Gestalt emerges during recurrent, unconscious processing within 420ms. The outcome of this processing, i.e., the conscious percept, determines, paradoxically, the first stages of visual processing.
4 septembre 2014

Conférence CerCo

Neural entrainment is less responsive to attentional demands in older listeners

Molly Henry
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

Jeudi 4 septembre 2014 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Increasing age is accompanied by decreasing speech comprehension performance in the presence of background noise that cannot be fully explained by peripheral hearing loss. For young, normal hearing listeners, separating speakers in a ?cocktail party? capitalizes on neural synchronization with attended speech. Thus, an intriguing but as of yet untested possibility is that age-related speech-comprehension deficits might be attributable to changes in the fidelity or flexibility of neural entrainment. I will present EEG data characterizing differences in entrainment capacities between younger (age 18?31) and older (age 61?77) adults under varying attentional demands (i.e., during active and passive listening). The talk will also touch on potential compensatory mechanisms that might lead to older adults performing behaviorally as well as younger adults despite having dysfunctional entrainment capacities. Finally, I will discuss a comparison of ?entrained? neural responses versus event-related potentials, a topic that has recently spurred some theoretical debate in the literature.
10 juillet 2014

Conférence CerCo

Development and evolution of communication:
focusing on gestures and manual asymmetries (Conférence CerCo)

Hélène Cochet
URI Octogone ? ECCD, Université Toulouse II

Jeudi 10 juillet 2014 · 11h Salle de conférence, Hôpital Purpan

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24 juin 2014

Séminaire · invité par Benedikt Zoefel

How musical rhythm entrains the human brain, explored with scalp and intracerebral EEG

Sylvie Nozaradan
Institute of Neuroscience, UCL, Belgium; Brams, UdeM, Canada

Mardi 24 juin 2014 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Getting entrained to music, and to musical rhythm and meter, is an extremely common human activity, shared by humans of all cultures. One of the major goals of our work is to explore the link between this entrainment behavior to musical rhythms on the one hand, and neurophysiological evidence of neural entrainment on the other hand. Specifically, we investigate whether the perception of temporal regularities induced by musical rhythms (i.e. the meter) could entrain neural activities at frequencies corresponding to these perceived regularities. To this aim, using scalp and intracerebral electroencephalography (EEG) in humans, we developed an approach to capture this processing of neural entrainment to musical rhythm and meter in the form of steady-state evoked potentials identified in the EEG spectrum. I will present several experiments conducted to test this frequency-tagging approach within various contexts (e.g. complex rhythms, mental imagery of meter, sensorimotor synchronization). Taken together, these studies show how the neural entrainment to musical rhythm can give us a unique gateway to explore the human brain function.

Sylvie Nozaradan (http://sylvienozaradan.webnode.com//), MD PhD, is currently post-doctorate research fellow at the Institute of Neuroscience (UCL, Belgium) and associate member at BRAMS (International laboratory for Brain, Music and Sound research, Montreal, Canada). She conducted her PhD on the neural entrainment to musical rhythms both at UCL (Belgium) and the BRAMS (UdeM, Montreal, Canada), under the co-supervision of Drs. André Mouraux and Isabelle Peretz. She has a double background, in music (B.Sc. and M.Sc. in Music performance and music writing, CrB, Belgium) and science (medical doctor degree, neurology, UCL).
5 juin 2014

Conférence CerCo

Orthographic processing in man, monkey, and machine

Jonathan Grainger
Laboratoire de Psychologie Cognitive, CNRS & Aix-Marseille Université

Jeudi 5 juin 2014 · 14h30 Salle de conférence, Hôpital Purpan

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Résumé
Orthographic processing lies at the interface between non-linguistic visual processing and the processing of truly linguistic entities, and therefore offers a privileged window onto how perception can shape language, and vice versa. In this talk I will describe how skilled readers process orthographic information, how this skill develops during reading acquisition, and how basic visual processes might adapt to the specific characteristics of printed words. Four main sources of evidence will be presented: 1) experiments examining basic processes in single word reading in children and adults; 2) experiments comparing perceptual processing of letter strings with strings of other kinds of visual stimuli; 3) a study of orthographic processing in baboons; and 4) neural network simulations of the results of the aforementioned studies.
4 juin 2014

Conférence CerCo

Intégration auditive bimodale:
vers une complémentarité des indices électriques et acoustiques chez le sujet implanté cochléaire

Mathieu Marx
Laboratoire Cerveau et Cognition & Service d\\\'Oto-Rhino-Laryngologie et Oto-Neurologie CHU Purpan

Mercredi 4 juin 2014 · 13h30 Salle de conférence, Hôpital Purpan

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3 juin 2014

Conférence CerCo

Subjective states of memory in autism

Céline Souchay
LEAD - CNRS/Université de Bourgogne

Mardi 3 juin 2014 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder primarily affecting social interaction and communication. It is a lifelong condition that affects a person?s development and how the brain processes information. Recent research has shown that people with ASD (including mostly high-functioning autism or Asperger syndrome) present with an impairment in the capacity to learn new information (episodic memory). Episodic retrieval is characterized by the subjective experience of remembering. This experience enables the co-ordination of memory retrieval processes and can be acted on metacognitively. In successful retrieval, the feeling of remembering may be accompanied by recall of important contextual information. On the other hand, when people fail (or struggle) to retrieve information, other feelings, thoughts and information may come to mind.
In this talk I will present the subjective and metacognitive basis of episodic memory function in autism, looking at recollection paradigms (such as source memory, and the report of recollective experience) and metacognitive paradigms such as the feeling of knowing). I will first focus on ?what memory feels like?, with a particular focus on the ability of children to report first-person experiences of remembering. I will then present studies developed in our lab looking at ?what we know about memory? and in particular what we know about our retrieval attempts and retrieval failures (metamemory). These studies reveal a complex fractionation of memory and metamemory in ASD. This pattern may reflect differences in brain functioning and genotype; and these may have different impacts on autistic traits.
27 mai 2014

Séminaire · invité par Michèle Fabre-thorpe

Dynamic center-surround interactions; are there visual flow detectors in the primary visual cortex?

Marc Pananceau
Unité de Neurosciences Information et Complexité, CNRS UPR-3293, Gif-sur-Yvette & Université Paris-Sud, Orsay

Mardi 27 mai 2014 · 11h Salle de conférence, Hôpital Purpan

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26 mai 2014

Séminaire · invité par Rufin Vanrullen

Cortical feedback relocation in V1 during interhemifield saccades

Grace Edwards
University of Glasgow, Department of Psychology

Lundi 26 mai 2014 · 10h30 Salle de conférence, Hôpital Purpan

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Résumé
The primary visual cortex (V1) is an integration area for feedforward sensory input and feedback internal signals from higher cortical areas. Some cortical feedback to V1 is thought to be predictive of sensory input. Since humans saccade approximately three times per second, a critical assumption is that feedback descending the cortical hierarchy can update to new retinotopic locations. My PhD aimed to provide evidence for feedback relocating to new retinotopic coordinates across saccades in V1. The first example of feedback relocation with saccades was found using the apparent motion illusion in psychophysical and functional brain imaging experiments. Apparent motion is the feedback filling-in of an illusory moving token between two rhythmically flashing dots. Our findings demonstrate that spatiotemporally specific feedback relating to the illusory token transfers to new retinotopic locations with saccade. In the second example we used fMRI to investigate a non-stimulated target region in V1 while a complex scene was presented in the contralateral hemisphere. By incorporating interhemifield saccades we found that contextual information of the image was fed-back to aid image processing after saccade at the new retinotopic position. In summary, these experiments demonstrate feedback relocation to new retinotopic locations with saccade in V1.
14 avril 2014

Séminaire · invité par Rufin Vanrullen

Modulation of alpha and gamma oscillations by benzodiazepines and its consequences for working memory performance

Diego Lozano Soldevilla
Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, The Netherlands

Lundi 14 avril 2014 · 14h Salle de conférence, Hôpital Purpan

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Résumé
Abstract: Animal research and computational modeling have demonstrated that GABAergic interneurons are crucially involved in synchronizing neuronal oscillations. We here asked if similar mechanisms generalize to human brain oscillations. Healthy participants participated in a double blind visual working memory study receiving placebo, 0.5mg and 1.5mg of lorazepam (a benzodiazepine upregulating GABAergic conductance) while we recorded their ongoing brain activity by magnetoencephalography. We found that occipital alpha power modulations during working memory maintenance decreased parametrically with drug dosage; this decrease predicted a reduction in performance. Contrary occipital stimulus induced gamma power increased with drug dosage. Importantly, the frequency of the gamma activity decreased with dosage, as predicted by models derived from rat the hippocampus. In conclusion, GABAergic interneurons are strongly implicated in the generation of alpha and gamma oscillations in the human visual system. Our findings bring us an important step closer to linking neuronal dynamics to behavior by embracing established animal models.
7 avril 2014

Conférence CerCo

Brain mechanisms for foveating a visual target here-and-now

Laurent Goffart
Institut de Neurosciences de la Timone, Marseille

Lundi 7 avril 2014 · 11h Salle de conférence, Hôpital Purpan

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Résumé
In most goal-directed movements, a spatial congruence is ultimately established between the location of the selected target and the movement endpoint.
Using the gaze orienting response as a probe to investigate the neurobiological foundations this sensorimotor "contact", I will present results of experiments that were performed in the feline and primate species in order to 1) understand how and why this sensorimotor association is altered when the medio-posterior cerebellum is functionally impaired and 2) test the neural processes that underlie the ability to ?intercept? and foveate a moving target.
3 avril 2014

Séminaire · invité par Rufin Vanrullen Et Rodika Sokoliuk

The role of human low frequency brain oscillations in gating cortical information processing:
Examples from visual perception and episodic memory

Simon Hanslmayr
Birmingham

Jeudi 3 avril 2014 · 11h Salle de conférence, Hôpital Purpan

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Résumé
The recent years has seen a substantial increase in publications exploring
the role of low frequency brain oscillations (<30 Hz) on human information
processing. Therefore, we now know that brain oscillations are crucially
and causally involved in complex cognitive tasks, like attention and
memory, and are unlikely to be an epiphenomenon. The next challenge of
this line of research is to understand the mechanisms via which brain
oscillations gate information processing, thereby going beyond a pure
correlative driven approach. In this talk, I will present studies from our
lab where we made some attempts in this direction in the domain of visual
perception and episodic memory. I will provide evidence from several
multi-modal imaging studies, employing EEG-fMRI, EEG-rTMS, intracranial
EEG and MEG. Together these studies suggest that low frequency brain
oscillations may regulate the information flow between higher and lower
cortical brain regions, and may code information in the episodic memory
system.
31 mars 2014

Séminaire · invité par Simon Thorpe

A Spike-Timing-Dependent Plasticity Model for Auditory Memory

Olivier Bichler
Centre d\'Intégration Nano-INNOV, CEA-List, Saclay

Lundi 31 mars 2014 · 14h30 Salle de conférence, Hôpital Purpan

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24 mars 2014

Conférence CerCo

Integration of a moving object by neuronal populations in awake monkey V1

Frédéric Chavane
Institut de Neurosciences de la Timone, Marseille

Lundi 24 mars 2014 · 14h30 Salle de conférence, Hôpital Purpan

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17 mars 2014

Séminaire · invité par Biao Han And Rufin Vanrullen

Predictive coding with spikes

Sophie Denève
Group for Neural Theory, Département d\'Études Cognitives, École Normale Supérieure

Lundi 17 mars 2014 · 14h Salle de conférence, Hôpital Purpan

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Résumé
Sensory and motor variables are represented by large population of neurons. This information should be easy to extract (e.g. a linear readout), as precise as possible, but also limit metabolic cost (i.e. maximally efficient). We will demonstrate here that spiking networks with Hebbian learning of feedforward connections and anti-hebbian learning of lateral connections produce such maximally efficient codes. In fact, the network can be seen as solving a simple quadratic optimization problem, were tuning curves and firing statistics can be entirely predicted from the input distributions and cost. The result is a balanced networks (i.e. maintaining the same level of excitation and inhibition) where each membrane potential monitors the coding error, e.g. the mismatch between the feed-forward inputs and the prediction of these inputs by lateral connections.

Through learning, initially regular, highly correlated spike trains evolve towards Poisson-distributed, asynchronous spike trains at much lower firing rates, as observed all over cortex. Importantly, howver, single unit variability is a consequence of degeneracy in the code, NOT noise: the population as a whole tracks the signal quasi-perfectly, even when single neurons are noisy. This suggests that balanced spiking networks are not equivalent to rate models, but in fact orders of magnitude more precise and efficient [Joint work with David Barrett, Wieland Brendel, Pietro Vertechi, Ralph Bourdoukan and Christian Machens]
12 mars 2014

Séminaire · invité par Pascal Barone

Images de classifications en modalité auditive:
identification des indices acoustiques de la perception de la parole.

Michel Hoen
Groupe de recherche Auditory Language Processing. Centre de Recherche en Neurosciences de Lyon.

Mercredi 12 mars 2014 · 11h Salle de conférence, Hôpital Purpan

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28 janvier 2014

Conférence CerCo

The neural basis of spatial frequency processing during scene perception

Carole Peyrin
Laboratoire de Psychologie & NeuroCognition (CNRS UMR 5105) Université Pierre Mendès-France

Mardi 28 janvier 2014 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Theories on visual perception agree that scene recognition begins with global analysis and ends with detailed analysis. Different results from neurophysiological, computational, and behavioral studies all indicate that the totality of visual information is not immediately conveyed, but that information analysis follows a predominantly coarse-to-fine processing sequence: low spatial frequencies (LSF) are analyze first, followed by high spatial frequencies (HSF). Yet, the ways spatial frequencies are processed within the cerebral cortex remain unclear. We aim to identify cerebral regions involved in spatial frequency processing and to clarify their attributes during scene perception. First, we provide evidence that, at the level of the occipital cortex, the processing of spatial frequency could not only be retinotopically mapped; it could also be lateralized in both hemispheres. Categorization of HSF (relative to LSF) scenes activates the foveal representation in all of the retinotopic areas of the occipital cortex and the categorization of LSF (relative to HSF) scenes activates more peripheral representations in the same cortical areas. Concomitantly, the right occipital cortex is predominantly involved in the categorization of LSF scenes processing while the left occipital cortex is predominantly involved in the categorization of HSF scenes. Second, our findings demonstrated that LSF information may rapidly reach high-order areas (such as the orbitofrontal cortex) to allow an initial coarse parsing of the visual scene, which could then be retro-injected through feedback into the occipital cortex to guide finer analysis on the basis of HSF. The occipital cortex might serve as an ?active blackboard? integrating the rapid analysis of LSF accomplished by higher order cortical areas and sent back by feedback connections to occipital areas to influence the subsequent analysis of HSF. Finally, we provide evidence that coarse-to-fine sequence processing constitutes the predominant strategy for scene categorization in a scene-selective cortical region: the parahippocampal place area.
16 janvier 2014

Conférence CerCo

Midcingulate cortex and adaptive behaviours in primates:
from feedback-based learning to checking

Emmanuel Procyk
Inserm U846

Jeudi 16 janvier 2014 · 14h Salle de conférence, Hôpital Purpan

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Résumé
(please note new hour)
2013 36
9 décembre 2013

Séminaire · invité par Lionel Nowak

Cortical oscillations and their alterations in transgenic models of disease

Maria-victoria Sanchez-vives
Idibaps Barcelona

Lundi 9 décembre 2013 · 11h Salle de conférence, Hôpital Purpan

Affiche
4 décembre 2013

Séminaire

Understanding representational geometries of neuronal population codes

Hamed Nili
Cognition and Brain Sciences Unit, Cambridge UK

Mercredi 4 décembre 2013 · 14h Salle de conférence, Hôpital Purpan

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Résumé
I will briefly explain the main 3 projects I have been doing in my PhD:
· Decoding within-category exemplar information
· Testing computational models
· Understanding invariance and selectivity
28 novembre 2013

Séminaire

Marqueurs comportementaux et cérébraux du vieillissement chez un primate, le Microcèbe

Fabienne Aujard
CNRS / MNHN. UMR 7179. Mécanismes adaptatifs: des organismes aux communautés. Brunoy

Jeudi 28 novembre 2013 · 11h Salle de conférence, Hôpital Purpan

Affiche
12 novembre 2013

Séminaire

Spatial cognition - different processes for different kinds of spaces

Tobias Meilinger
Max Planck Institute for Biological Cybernetics

Mardi 12 novembre 2013 · 11h Salle de conférence, Hôpital Purpan

Affiche
8 novembre 2013

Séminaire

Tracking objects, illusions and guesses with the eyes:
human smooth pursuit as a dynamical probe of visual and predictive information processing

Anna Montagnini
Institut des Neurosciences de la Timone (INT, Marseille), équipe InVibe

Vendredi 8 novembre 2013 · 11h Salle de conférence, Hôpital Purpan

Affiche
29 octobre 2013

Séminaire

Does the pattern of prefrontal connections give us clues about the function of the primate claustrum?

David Reser
Department of Physiology. Monash University Melbourne, Australia

Mardi 29 octobre 2013 · 11h Salle de réunion E2, Hôpital Purpan

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Résumé
http://www.med.monash.edu.au/physiology/staff/reser.html
25 octobre 2013

Séminaire

Exploring the social brain in human and non-human primates

Rogier Mars
University of Oxford

Vendredi 25 octobre 2013 · 11h Salle de conférence, Hôpital Purpan

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Résumé
For a social species like our own evolutionary success necessitates the ability to navigate a world full of conspecifics. Consequently, humans are extremely sensitive to information about others? emotional states or intentions as provided by cues such as facial expression or body movement. It has been argued that the size and complexity of the human brain is a reflection of the difficulty in
navigating our social environment. However, the relationship between areas in the human brain concerned with processing social information and similar areas in the non-human primate brain remains largely unexplored. A number of recent studies have searched for areas with similar response characteristics across species, but these studies have been largely hampered by the difficulty of engaging non-human primates in social tasks comparable to those of the human. In this talk, I will take a different approach to studying the organization of the human social brain and its similarity to the ?monkey model?. I will use measures of structural and functional connectivity to compare these brains on anatomical criteria. This approach allows me to characterize the human social brain in more detail, but also provides some direct evidence for the relationship between human dorsal frontal and anterior cingulate cortex and its proposed homologues in the macaque brain. In addition, it suggests a relationship between one area in the human brain that is associated with uniquely human social abilities, the so-called temporoparietal junction area (TPJ), and areas in the macaque temporal cortex.
17 octobre 2013

Séminaire

The limits of human stereo vision in space and time.

Marty Banks
Univ. California-Berkeley Visual space perception lab

Jeudi 17 octobre 2013 · 11h Amphi Ducuing, Hôpital Purpan

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Résumé
To encode binocular disparity and thereby enable stereoscopic depth perception, the visual system determines the displacement of an image patch in one eye that yields the highest correlation with a patch in the other eye. This occurs in visual cortex after spatio-temporal filtering of the monocular signals. The computation of inter-ocular correlation after filtering imposes fundamental bounds on the disparities that can support depth perception. We quantified those bounds by measuring humans? ability to see disparity variation for various spatial and temporal frequencies. We find that minimum-disparity thresholds cut off at very low spatial and temporal frequencies, consistent with disparity sensitivity of neurons in primary visual cortex. Those thresholds are well predicted by a space-time separable function, suggesting that the underlying neural mechanisms are also separable. We also find upper-disparity limits characterized by a spatio-temporal, disparity-gradient limit: To be visible, disparities cannot change more than a fixed amount for a given change in space-time. The volume of visible disparity variations is remarkably restricted compared to the corresponding volume for luminance processing. The results provide important insight into the properties of neural mechanisms underlying the perception of depth from disparity, such as the possibility of joint disparity-motion sensors in V1. They also suggest a novel technique for compressing stereo video.
7 octobre 2013

Séminaire

Modeling brain development using medical image analysis

Maria Murgasova , Research Associate
King\'s College London

Lundi 7 octobre 2013 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Understanding human brain development and mapping structure of the developing brain in health and disease are the research areas that underpin development of novel neuroprotective and neural rescue therapies, with the ultimate aim of reducing the number of children who suffer brain damage at the time around the birth. Magnetic resonance imaging is ideal for visualization of the structure of the developing brain and advanced modalities such as DTI or fMRI can further reveal its microstructure and function. Application of standard image analysis techniques to perform population studies is challenging during pre-natal and neonatal period. In this talk I will describe how 4D spatio-temporal models of the brain can help visualise its development and aid the segmentation of the brain structures. I will further present motion correction techniques for fetal MRI, which will soon allow more detailed understanding of how the brain develops before birth. Finally I will describe how 3D u
ltrasound of fetal brain might play an increased role in clinical practice in future.
4 octobre 2013

Séminaire

Multiple objects in approach:
from time-to-contact estimations to cars avoidance

Robin Baurès
Laboratoire d\\\'Adaptation Perceptivo-Motrice et Apprentissage (LAPMA), Université Paul Sabatier, Toulouse

Vendredi 4 octobre 2013 · 14h Salle de conférence, Hôpital Purpan

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Résumé
How do humans deal to estimate multiple time-to-contacts (TTCs) in the same time? While the accuracy of TTC perception has been assessed at length for single approaching objects, close to nothing is known about observers' ability to make simultaneous TTC judgments for two or more objects. Such judgments are required in many everyday situations, such as when crossing a multi-lane street or in multi-player ball games.
Here we studied observers? performances in a prediction motion task when one or two objects were displayed. In such a task, a moving object is occluded some time before it reaches the observer or a specified target. The observer is required to make a simple response at the time the object would have reached the target, had it continued its trajectory. In addition, participants had to pursue one of the two objects, or had no eye movements? instruction. Our results showed the incapacity of the visual system to make two accurate TTC estimations at the same time, and interestingly, the results were dependent on the gaze allocation instructions.
We then tried to replicate these findings in a more natural task. In a driving simulator, we asked participants to drive their car trough an intersection, in which one or two gaps (the temporal separation between two consecutive vehicles) could be approaching on two adjacent lanes, and either from the same side or from the opposite sides. The stimuli were designed such that only the shortest gap was decision-relevant. The results failed to replicate the outcomes of the two first experiments, and showed that the longer ? and irrelevant ? gap influences the street-crossing decisions when the two gaps were in sight simultaneously, observers were more willing to cross the street when they had access to information about the irrelevant gap. This is however not the case when the two gaps could not be seen simultaneously but only sequentially. The results are discussed within the framework of perceptual averaging process
Differences in the two sets of experiments will be discussed, and conclusions about the visual system capacities and practical implications for road safety are presented.
20 septembre 2013

Séminaire

L'inadéquation des bilans audiométriques classiques, révélée par les modèles animaux

Paul Avan
Equipe Biophysique Neurosensorielle UMR INSERM 1107. Clermont-Ferrand

Vendredi 20 septembre 2013 · 10h Salle de conférence, Hôpital Purpan

Affiche
19 septembre 2013

Séminaire

Approche psychophysique de la perception auditive para et extra linguistique chez le sujet sourd implanté cochléaire

Mathieu Marx
Soutenance de Thèse de Doctorat

Jeudi 19 septembre 2013 · 14h Salle de conférence, Hôpital Purpan

Affiche
18 juillet 2013

Séminaire

The Lateralisation of Emotion in Social Mammals

Dr. Adam Ds Milligan
University of Stirling

Jeudi 18 juillet 2013 · 11h Salle de conférence, Hôpital Purpan

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Résumé
The study of lateralisation has taken several forms ranging from investigating morphological asymmetries to research on lateralised motor and perceptual functions with many studies successfully evidencing lateralisation in a variety of species. This study, featuring two species of primates, Papio Anubis and Macaca mulatta, and the spotted hyena, Crocuta crocuta, investigated visual field biases with the aim of determining whether emotional valence underpins these biases whilst also considering the influence of a number of other factors such as emotional intensity, age, sex, rank and, for the first time, oestrus cycles (Papio anubis only). Furthermore, this study hoped to establish whether Campbell?s (1982) Right Hemisphere Hypothesis or Silberman & Weingartner?s (1986) Valence Hypothesis offered the more valid theory for the lateralisation of emotion by considering interactions across the full spectrum of emotion ? a question the almost exclusive investigation of negatively affective scenarios by previous studies has been unable to answer. Strong biases were found at the individual level in all three species and a population level left side bias was found for Crocuta crocuta, thus providing the first evidence of significantly lateralised behaviour in a large carnivore and, for this species at least, lending some support to Campbell?s (1982) Right Hemisphere hypothesis. Additionally in Papio anubis, negative valence behaviours were significantly lateralised to the left visual field and high intensity behaviours were found to occur more frequently in the mid and central visual fields with males also significantly less active in their extreme periphery than females. Evidence of a similar contrast was found between in-oestrus and non-oestrus females of the same species with the latter significantly more lateralised, and the results also suggesting that the direction of lateral bias is influenced by oestrus status for sexual behaviours. This study found that separating the visual field into five sections (extreme left, mid left, centre, mid right and extreme right) allows a more accurate insight into the lateralisation of visual perception than the traditional hemifield model. Finally, a more conservative method is proposed for analysing behavioural data from future studies within this field and suggests that these methods provide a more accurate representation of the lateralisation of emotion than those previously employed.
11 juillet 2013

Séminaire

Visual feature integration in the lateral Intraparietal Area

Guilhem Ibos
Freedman\'s laboratory, University of Chicago, Department of Neurobiology

Jeudi 11 juillet 2013 · 11h Salle de conférence, Hôpital Purpan

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2 juillet 2013

Séminaire

ANANATOMICAL AND PHYSIOLOGICAL ORGANISATION OF THE VISUAL PATHWAYS FOLLOWING LESIONS OF PRIMARY VISUAL CORTEX IN EARLY LIFE

Pr Marcello Rosa
Department of Physiology Monash University

Mardi 2 juillet 2013 · 11h Salle de conférence, Hôpital Purpan

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Résumé
In adult primates, projections from the lateral geniculate nucleus (LGN) to the primary visual area (V1) are essential for conscious visual perception. Partial damage to V1 in adults leads to irreversible blindness in a defined region of the visual field (scotoma). In contrast, V1 lesions in infancy allow preservation of some visual capacities, possibly due to rearrangement of thalamic projections to extrastriate areas. However, we don't know to what extent these pathways involve the LGN, particularly since many projection neurones in this nucleus die, as a result of severe retrograde degeneration, following infant V1 lesions.

We studied the physiological properties and connections of LGN cells in marmoset monkeys that had unilateral ablation of the representation of central 30-40° of visual field in V1, under isoflurane anaesthesia, between 2 and 36 weeks of age. Following survival times of 1-2 years, to allow development into full adulthood, single-unit activity was recorded in the LGN. We found that, despite massive cell loss, the sector of the LGN that sent projections to the lesioned part of V1 (lesion projection zone) contained neurones with clear visual responses. The receptive fields of these neurones were well-defined, and generally followed the expected patterns of topographic representation and eye dominance. However, in many instances these receptive fields were enlarged, relative to those of cells outside the lesion projection zone.

Injections of retrograde tracers in extrastriate area MT of the same animals labelled large neurones in the LGN, which concentrated in the lesion projection zone. In addition, concurrent recordings in MT of marmosets that received V1 lesions within the first 6 weeks of postnatal life demonstrated many neurons with receptive fields inside the scotoma created by V1 lesion. These responses were very similar to those recorded in neurons with receptive fields outside the lesion projection zones in terms of firing rate, signal-to-noise ratio, and latency. In addition, the normal retinotopic organization of MT was maintained. Nonetheless, we found evidence of a very specific functional deficit: direction selectivity, a key physiological characteristic of MT which is known to be preserved in many cells following adult V1 lesions, was absent.

These results demonstrate that the surviving LGN neurones are plausible candidates for mediators of the pathway that allows residual vision following V1 lesions in early life. Further, they demonstrate that lesion-induced reorganization of afferent pathways is sufficient to develop robust visual function in primate extrastriate cortex, highlighting a likely mechanism for the sparing of vision following neonatal V1 lesions. However, they also suggest that interactions with V1 in early postnatal life are critical for establishing stimulus selectivity in area MT.
25 juin 2013

Séminaire

Pinpointing the origin of behavioural variability in perceptual decision-making

Valentin Wyart
Laboratoire de Neurosciences Cognitives (INSERM U960), Ecole Normale Supérieure, Paris

Mardi 25 juin 2013 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Human perceptual decisions often fluctuate beyond what can be explained by variability in the underlying sensory stimulation. Various hypotheses exist to explain this "intrinsic" perceptual variability, such as noise in our sensory systems, or sampling from an inferred probability distribution over possible percepts. Using a combination of visual psychophysics and modelling, I will first show how noise in the inference process itself can be a major contributor to behavioural variability. I will then identify and characterise a processing constraint on sequential evidence accumulation which gives rise to inference noise in subsequent perceptual decisions. For this purpose, I will use model-based analyses of human EEG signals recorded during multi-sample visual categorisation. The findings emphasise the existence of a central processing bottleneck which limits, in terms of capacity, our ability to integrate sensory evidence over space and time.
24 juin 2013

Séminaire

Attentional and Perceptual Cycles:
Investigations using psychophysics, electroencephalography and transcranial magnetic stimulations

Laura Dugué

Lundi 24 juin 2013 · 14h Salle de conférence, Hôpital Purpan

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Résumé
Do we experience the world continuously or as a discrete sequence of events, like samples of a video camera? This is the first question motivating my PhD work. Previous experiments have shown that visual information may be sampled periodically by attention, this processing being supported by oscillations in the EEG brain activity. In paper 1, using TMS, we were able to establish for the first time a causal relation between the phase of ongoing oscillations, brain excitation and visual perception. In another series of experiments, we explored the spatio-temporal behaviour of attention during visual search tasks. Using various experiments (papers 2 to 4) and various techniques (TMS, EEG, psychophysics), we brought convincing and converging evidence in favour of a periodic sampling of visual information by attention. Moreover, in paper 5, we were able to clarify an age-old debate concerning visual search tasks by ruling out the possibility that attention is distributed in parallel over all stimuli in the search array, suggesting a sequential processing of the different stimuli during the search. Overall, this PhD work gives strong arguments in favour of a periodic, and perhaps sequential, processing of visual information by attention.
19 juin 2013

Séminaire

Neural Mechanisms of Perceptual Stability

Bart Krekelberg
Rutgers University

Mercredi 19 juin 2013 · 11h Salle de conférence, Hôpital Purpan

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13 juin 2013

Séminaire

Learning of statistical regularities during the analysis of visual scenes

Dr. Annabelle Goujon
Laboratoire de Psychologie Cognitive, Marseille

Jeudi 13 juin 2013 · 11h30 Salle de conférence, Hôpital Purpan

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11 juin 2013

Séminaire

Comment le cerveau perçoit-il les objets d'art?

Simon Thorpe
CerCo UMR 5549

Mardi 11 juin 2013 · 13h30 Salle de conférence, Hôpital Purpan

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Résumé
Je propose de refaire la conférence grand public que j'ai donné dans le cadre de la semaine du Cerveau le 11 mars 2013. La conférence serait en Français et accessible à tous.

"Chaque personne qui regarde une ?uvre d'art, que ce soit un tableau, une photo, une statue ou un film va aborder l'objet de façon personnelle, tout simplement parce que sa façon d'explorer l'objet avec son ?il sera unique. Mais quelle est l'origine de ces différences? Dans quelle mesure notre façon d'aborder une ?uvre dépendra-t-elle des facteurs liés aux propriétés des neurones de notre système visuel? Peut-on modifier ces propriétés neuronales par notre expérience, c'est-à-dire par l'influence de facteurs culturels? Voici quelques-unes des questions que je souhaite soulever dans cette brève présentation."
5 juin 2013

Séminaire

Imagerie cérébrale fonctionnelle par ultrasons

Mickael Tanter Et Ivan Cohen
Institut Langevin ESPCI et Neurobiologie des Processus Adaptatifs UPMC

Mercredi 5 juin 2013 · 11h Salle de conférence, Hôpital Purpan

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Résumé
L'équipe «Physique des Ondes pour la Médecine et la Biologie » est une unité Inserm/CNRS/ESPCI (Inserm U979) créée en Janvier 2008 au sein de l'Institut Langevin. Elle regroupe des physiciens spécialisés dans le domaine de la physique des ondes pour l?imagerie biomédicale allant des échelles cellulaires (optique) à l?échelle des organes (Ultrasons). Ses principaux axes de recherche consistent à développer des approches innovantes d'imagerie pour la prévention et le diagnostic basées sur les technologies ultrasonores et optiques, mais aussi des techniques de thérapie non-invasives par ultrasons focalisés.

Présentation de Ivan COHEN : Functional networks, from whole brain to neuronal populations

Cerebral processes and pathologies involve cascades of events from myriads of cells up to a whole nervous system. I will present our attempts to go from symptoms or behavior back to brain areas and cellular interactions, using slice preparations and functional ultrasound (fUS) imaging.
The simplest way to localize tissue hyperactivity at a submillimeter, local network, level uses extracellular multiunit recordings. In human temporal lobe epilepsy, where the focus is anatomically localized at a centimetric scale, these recordings were used on therapeutical biopsies from patients. Spontaneously active areas could be pinpointed in vitro, revealing synaptic interactions reminiscent of immature tissue. However, in most cases identifying brain areas of interest remains a challenge. Functional ultrasound imaging on rodents was developed for this purpose, using vasodilation and contraction as indirect markers of tissue activity. This technique proved to measure cerebral blood volume with high sensitivity, spatial and temporal resolutions. Since probes are small and lightweight it becomes possible to image non anesthetized, mobile animals. Our preliminary experimental protocol attaches a miniature ultrasound probe atop a cranial window, providing images of comparable quality in the awake/mobile and anesthetized contexts. Our perspective is to use this approach to study brain area interactions in spatial navigation and pathologies sensitive to anesthetics.
31 mai 2013

Séminaire

Computational imaging biomarkers of neurodegenerative and vascular diseases

Olivier Colliot
Brain and Spine Institute (ICM) CNRS-INRIA-Inserm-UPMC

Vendredi 31 mai 2013 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Neuroimaging techniques allow monitoring in vivo structural and functional alterations associated with disorders of the central nervous system. A current challenge for brain image analysis is to be able to automatically extract biomarkers of pathologies from neuroimaging data. Biomarkers can then be used to support the diagnosis, to track disease progression, to
predict the future state of a given patient or to monitor the efficacy of new drugs in clinical trials. The design of imaging biomarkers poses important methodological questions to image analysis research. How to extract quantitative measures from brain images? How to compare measures across individuals and populations? How to learn discriminative models
from the data? In this talk, I will present how these questions can be tackled through image segmentation, inter-individual registration, shape modeling and machine learning methods. Examples of applications to neurodegenerative (mainly Alzheimer?s disease) and cerebrovascular disorders will be presented.
26 avril 2013

Séminaire

Neuromorphic Event-based time oriented vision:
A framework to unify computational and biological vision.

Ryad Benosman
Equipe \"Vision et Calcul Naturel\", Institut de Vision, Paris

Vendredi 26 avril 2013 · 11h Salle de conférence, Hôpital Purpan

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11 avril 2013

Séminaire

Granger Causality in Neuroscience:
from snail brains to consciousness

Anil Seth
University of Sussex

Jeudi 11 avril 2013 · 11h Salle de conférence, Hôpital Purpan

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10 avril 2013

Séminaire

Individual differences in brain structure involved in visual awareness and attention

Ryota Kanai
University of Sussex

Mercredi 10 avril 2013 · 11h Salle de conférence, Hôpital Purpan

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4 avril 2013

Séminaire

Julie Grèzes
Institut d\'étude de la cognition

Jeudi 4 avril 2013 · 14h Salle de conférence, Hôpital Purpan

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4 avril 2013

Séminaire

The role of the interactions between the emotional and the motor systems during social interactions.

Dr. Julie Grèzes
Laboratoire de Neuroscience Cognitive, ENS Paris

Jeudi 4 avril 2013 · 14h Salle de conférence, Hôpital Purpan

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Résumé
It is widely agreed that body language is a powerful source of information about emotions and intentions in our daily encounters with people. We will present our recent fMRI studies that aimed at identifying the neural bases involved in processing emotions from body actions and their link with the motor system. We concentrated on two emotions, namely fear and anger, as they both represent potential threats. We assessed the influence of context (in terms of allocation of attentional resources and functional significance for the self). We hope to show that body expressions of emotions are decoded as interactive social signals (social affordances) in the sense that they require one to automatically adapt or regulate one's own behavior.
28 mars 2013

Séminaire

Population signals for motion vision in area MT of marmoset

Sam Solomon
University College London & The University of Sydney

Jeudi 28 mars 2013 · 14h30 Salle de conférence, Hôpital Purpan

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27 mars 2013

Séminaire

Spatiotemporal contextual effects in human observers

Isabelle Mareschal
University College London & The University of Sydney

Mercredi 27 mars 2013 · 14h30 Salle de conférence, Hôpital Purpan

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12 mars 2013

Séminaire

Exploring visual cognition with intracranial EEG:
specialization, imagination and active perception

Carlos Hamame
Laboratoire de Psychologie Cognitive, Aix-Marseille

Mardi 12 mars 2013 · 11h Salle de conférence, Hôpital Purpan

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19 février 2013

Séminaire

The interactions between bottom-up and top-down information processing:
a tool for understanding the N170 face component and for studying perceptual atypicalities in autism.

Boutheina Jemel
Montréal

Mardi 19 février 2013 · 11h Salle de conférence, Hôpital Purpan

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15 février 2013

Séminaire

Toward a biological explanation of subjective experience?

Catherine Tallon-baudry
LNC Ecole Normale Supérieure

Vendredi 15 février 2013 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Conscious vision is accompanied by both enhanced cognitive abilities and a subjective experience. I will present here experimental evidence to show that those two aspects of consciousness can be dissociated both at the neural and behavioral level. I will propose that subjective experience takes place at an integrated level, and that that the first person perspective necessary for subjective experience is linked to a minimal sense of the self based on physiological self-monitoring processes: fluctuations in neural responses to heartbeats before stimulus onset can predict fluctuations in visual awareness.
8 février 2013

Séminaire

Paranormal Phenomena

Simon Thorpe
CerCo UMR 5549

Vendredi 8 février 2013 · 13h Salle de conférence, Hôpital Purpan

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4 février 2013

Séminaire

The importance of weak connections in the cortex

Henry Kennedy
Stem Cell and Brain Research Institute. Department of Integrative Neuroscience. Bron (France)

Lundi 4 février 2013 · 11h Salle de conférence, Hôpital Purpan

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25 janvier 2013

Séminaire

Séminaire

Niko Busch
Modeling the effect of spontaneous oscillations on visual perception

Vendredi 25 janvier 2013 · 11h Salle de conférence, Hôpital Purpan

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Résumé
The brain is never at rest. Even in the absence of or preceding external stimuli, spontaneous, internally generated neural activity can be observed using optical imaging, fMRI, or electrophysiological recordings. How does this spontaneous brain activity interact with the processing of external stimuli? One type of spontaneous brain activity are ongoing electrophysiological oscillations, particularly in the alpha frequency band (approximately at 10 Hz). Numerous studies have demonstrated that alpha oscillations just before the onset of a visual stimulus have an inhibitory effect on visual perception. In this presentation, I will argue that we still know very little about the nature of this inhibitory effect. I will demonstrate that a better theoretical understanding can be achieved by modeling the effect of pre-stimulus alpha oscillations on psychophysical performance. Our results show that pre-stimulus alpha oscillations exert their inhibitory effect by modulating the gain of the psychometric function, resembling the effect of spatial attention on visual perception. I will conclude by formulating questions that need to be addressed from a modeling perspective in order to extend our understanding of how pre-stimulus alpha oscillations affect the processing of visual information.
18 janvier 2013

Séminaire

Microélectrodes implantables souples à surface nanostructurée pour la stimulation et l?enregistrement de l?activité cérébrale

Christian Bergaud
Equipe Nanobiosystèmes, LAAS-CNRS , Toulouse

Vendredi 18 janvier 2013 · 14h30 Salle de conférence, Hôpital Purpan

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2012 25
14 décembre 2012

Séminaire

Computational modeling of biological systems

Muriel Mescam
CerCo

Vendredi 14 décembre 2012 · 11h Salle de conférence, Hôpital Purpan

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4 décembre 2012

Séminaire

Bottom-up and top-down processing in visual perception

Thomas Serre
Brown University, Cognitive Linguistic & Psychological Sciences Department

Mardi 4 décembre 2012 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Perception involves a complex interaction between feedforward sensory-driven information and feedback attentional, memory, and executive processes that modulate such feedforward processing. A mechanistic understanding of feedforward and feedback integration is a necessary step towards elucidating key aspects of visual and cognitive functions and dysfunctions.

In this talk, I will describe a computational framework for the study of visual perception. I will present computational as well as experimental evidence suggesting that bottom-up and top-down processes make a distinct and essential contribution to the recognition of complex visual scenes. A feedforward hierarchical architecture may provide a satisfactory account of ?immediate recognition? corresponding to the first few hundred milliseconds of visual processing. However, such an architecture may be limited in recognizing complex visual scenes. I will show how attentional mechanisms and cortical feedback may help improve object recognition performance in complex cluttered scenes.
3 décembre 2012

Séminaire

Soutenance de thèse :
Etude sur la pensée animale:
continuité neuro-cognitive de la catégorisation visuelle.

Maxime Cauchoix
CerCo

Lundi 3 décembre 2012 · 14h Salle de conférence, Hôpital Purpan

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7 novembre 2012

Séminaire

Executive functions in baboon (Papio papio):
inter-individual variabilities

Elodie Bonté
Centre de Recherche Cerveau & Cognition, Université Paul Sabatier, Toulouse

Mercredi 7 novembre 2012 · 11h Salle de conférence, Hôpital Purpan

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24 octobre 2012

Séminaire

Cross-modal plasticity and functional specialization in early blind humans

Laurent Renier
Université catholique de Louvain, Institute of Neuroscience (IoNS). Bruxelles

Mercredi 24 octobre 2012 · 10h30 Salle de conférence, Hôpital Purpan

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Résumé
Rappel
9 octobre 2012

Séminaire

From sleeping zombies to phenomenal babies :
new insights in consciousness research

Sid Kouider
Ecole Normale Supérieure

Mardi 9 octobre 2012 · 11h Salle de conférence, Hôpital Purpan

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Résumé
My talk will focus on the depth of nonconscious perceptual
processes, and on the mechanisms leading to conscious access. My
presentation will be centered around 3 topics. First, I will show how novels
approaches relying either on gaze-contingent crowding or on lateralized
readiness potentials in sleepers can lead to new insights regarding the
depth of nonconscious perceptual processes. Secondly, I will present new
electrophysiological studies aimed at testing whether and how preverbal
infants are conscious of their environment; Finally, I will focus on the
existence of phenomenal consciousness without attention/access, show how it
is empirically flawed and discuss the alternative partial awareness
hypothesis.
5 octobre 2012

Séminaire

Models of stroke in the hypertensive rat and the marmoset:
neuroimaging investigations

Omar Touzani
CERVOxy team \\

Vendredi 5 octobre 2012 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Even if many pharmacological treatments of ischemic stroke have been proven efficient in animal studies, none could be transferred to the clinical situation with the same efficiency. One of the issues that has been put forward to explain this failure of translation of the bench results to the bed side is the inadequacy of the animal models of stroke. Indeed, most of the available preclinical studies rely on the use of young and healthy rodents devoid of concomitant pathologies such as chronic arterial hypertension which is often associated with stroke in Human. Thus, many recent recommendations for preclinical investigations designed to develop stroke therapies call for the use of models of stroke with comorbid factors as well as the use of higher order species such as non-human primates in addition to rodent models. These reviews also advocate the use of multiple-outcome measures (functional deficits, neuroimaging along with post-mortem neuropathology) both at the acute and the chronic stages of stroke to assess the efficacy of a given treatment.
In this talk, we will present mainly neuroimaging data to illustrate, firstly, the impact of arterial hypertension on the kinetics of evolution of the ischemic penumbra in the rat, and secondly, the value of employing non human primates (particularly the marmoset) in the studies of the pathophysiology and the treatment of brain ischemia.
2 octobre 2012

Séminaire

Soutenance de Thèse - Electrolencéphalographie et Interfaces Cerveau-Machine :
nouvelles méthodes pour étudier les états mentaux

Romain Grandchamp
CerCo

Mardi 2 octobre 2012 · 14h Salle de conférence, Hôpital Purpan

Affiche
28 septembre 2012

Séminaire

Soutenance de thèse :
Study of the electroencephalographic correlates of mind wandering and meditation

Claire Braboszcz
CerCo

Vendredi 28 septembre 2012 · 14h Salle de conférence, Hôpital Purpan

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Résumé
Trying to focus our attention on any given physical or mental object, we soon re-
alize it cannot be kept indefinitely focused and soon drifts towards other thoughts or
sensations, a phenomenon called mind wandering. Interestingly, ancient traditions of
meditation practices have developed a large variety of methods aiming at developing
the awareness of mind wandering episodes and training the mind to remain focused.
It is important to point out that the knowledge of the focus of attention is a type of
information that is private to the subject and that can only be assessed using methods
that take into account first-person perspectives. During my thesis, I studied both the
mind wandering and the meditation mental states in an effort to better understand
what is happening in the brain when someone meditates. First, regardless of the med-
itation tradition, mind wandering is ever present during meditation and it seemed
like an ideal starting point for studying meditation. It is also a phenomenon that is
not unique to meditation and is present whenever a person attempts to focus. Using a
novel EEG protocol, we show that mind wandering episodes are accompanied by in-
creased amplitude at low frequencies in the delta (1-3Hz) and theta (4-7Hz) frequency
bands as well as a reduction of pre-attentive sensory processing as shown by the anal-
ysis event-related potentials. These results indicate that mind wandering is associated
with a lower vigilance level, resembling early stages of drowsiness. These results are
consistent with some Buddhist texts on meditation, in which mind wandering is con-
sidered to be a state of relative sleep where the mind is not aware. Then, we realized
a comparative study of EEG activity during meditation to attempt to sort out the ori-
gin of the divergent results found in the literature. We recorded the spontaneous EEG
activity of 3 groups of meditators from 3 different meditation traditions in addition to
a non-meditator group using the same protocol and equipment. We showed that all
groups of meditators had higher 60-110Hz gamma amplitude when compared to the
controls during meditation, possibly indicating different attentional processes in med-
itators. No differences were found between the mental control state and the meditative
state in meditators, suggesting that we were observing trait rather than state effects of
meditation. Overall, our study emphasizes the need to better define what could be the
best control mental state for meditation. During this work, I also explored the method-
ologies allowing the collection of accurate subjective data. Our work brings new data
in the field of consciousness, mind wandering and meditation study, but the road will
be long before we fully understand the mechanisms underlying our inner life.
27 septembre 2012

Séminaire

Understanding self-generated thought

Jonathan Smallwood
MPI for Human, cognitive and brain science, Leipzig

Jeudi 27 septembre 2012 · 11h Salle de conférence, Hôpital Purpan

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Résumé
The mind spends a large amount of time engaged in self-generated thought and yet as psychological scientists and we are barely scratching the surface of how this important form of thought operates. The current talk will argue that this basic form of cognition depends upon (i) the capacity to decouple attention from perception, which reduces competition with concurrent perceptual input, and (ii) that the deployment of control processes upon self-generated information, which can help transform a thought fragment into an internal train of thought. It will be demonstrated that in combination these two processes can explain several features of self-generated thought, and in particular of how the experience can have both costs and benefits depending on the context in which it occurs.
20 septembre 2012

Séminaire

Understanding face perception by means of fast periodic visual stimulation

Dr. Bruno Rossion
Université catholique de Louvain - IPSY - IoNS

Jeudi 20 septembre 2012 · 11h Salle de conférence, Hôpital Purpan

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19 septembre 2012

Séminaire

Soutenance de thèse

Roger Koenig-robert
How does sense emerge in the visual system? The cognitive visual system

Mercredi 19 septembre 2012 · 14h Salle de conférence, Hôpital Purpan

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Résumé
How does sense emerges in the visual system? In this thesis we will be focused on the visual
system of human and non-human primates and their large capacity of extract and represent
visual information. We studied several levels of visual representations from those related to
the extraction of coarse visual features to the emergence of conscious visual
representations. This manuscript presents six works in which we explored: (1) the visual
features necessary to perform ultra-rapid visual categorization in monkeys and humans
using psychophysics, (2) the spatio-temporal dynamics of visual attention in humans using
psychophysics, (3) the neural correlates of high-level visual representations using EEG tanks
to the development of an innovative technique called SWIFT, (4) the neural correlates of
visual consciousness under binocular rivalry using EEG, (5) the synchrony of brain signals as a
function of conscious recognition using intracranial electrodes implanted in epileptic
patients and (6) the neural correlates associated with conscious perception in monkeys using
intracranial electrodes. The results of these works allowed outlining a tentative model of
visual perception aimed to dissociate attention and consciousness.
18 septembre 2012

Séminaire

Decoding the first 800ms of object perception

Dr. Thomas Carlson
University of Maryland - Department of Psychology

Mardi 18 septembre 2012 · 16h Salle de conférence, Hôpital Purpan

Affiche
10 septembre 2012

Séminaire

Restoring vision in blind patients:
from retinal prostheses to optogenetic therapy.

Serge Picaud
INSTITUT DE LA VISION UMR_S968 Inserm / UPMC/ CNRS 7210 / CHNO des Quinze-Vingts

Lundi 10 septembre 2012 · 11h Salle de conférence, Hôpital Purpan

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Résumé
When patients lose their photoreceptors in diseases like retinitis
pigmentosa or age-related macular degeneration, their residual retina still
contains two neuronal layers. These layers are normally compressing and
extracting important visual information prior to their transfer to the brain
via the optic nerve. Retinal prostheses are therefore aiming at
reintroducing some visual information by electrically stimulating these two
retinal layers. Clinical trials have already validated this concept but the
visual performances of patients are currently limited. To increase the
spatial resolution of electrodes, we have developed a 3D implant structure.
We also developed diamond coating on the electrodes to take advantage of its
biocompatibility and its semiconductive properties. Recently, an alternative
strategy, the optogenetic therapy, has emerged where neuronal activation can
be achieved with bacterial or alga proteins generating currents under light
stimulation. In parallel, we have therefore worked on this strategy because
it could increase further the spatial resolution to the cellular level.
11 juillet 2012

Séminaire

Embedded bio-inspired electronic architectures for real time pattern recognition

Prof. Michel Paindavoine
Université de Bourgogne, Laboratoire d\'Etude de l\'Apprentissage et du Développement (UMR 5022), Dijon

Mercredi 11 juillet 2012 · 11h Salle de conférence, Hôpital Purpan

Affiche
15 juin 2012

Séminaire

La reconnaissance des visages :
Apport de la technique des potentiels évoqués

Stéphanie Caharel
Université de Nancy

Vendredi 15 juin 2012 · 11h Salle de conférence, Hôpital Purpan

Affiche
14 mai 2012

Séminaire

ANNULE

Prof. Michel Paindavoine
Université de Bourgogne, Laboratoire d\'Etude de l\'Apprentissage et du Développement (UMR 5022), Dijon

Lundi 14 mai 2012 · 14h Salle de conférence, Hôpital Purpan

Affiche
Résumé
Michel Paindavoine a du annuler sa visite
19 avril 2012

Séminaire

Rôle du sommeil dans la mémoire émotionnelle

Paul Salin
Physiopathologie des réseaux neuronaux du cycle sommeil CRNL Lyon

Jeudi 19 avril 2012 · 11h Salle de conférence, Hôpital Purpan

Affiche
18 avril 2012

Séminaire

Habilitation à Diriger les Recherches

Pascal Girard
Cerveau & Cognition

Mercredi 18 avril 2012 · 14h Salle de conférence, Hôpital Purpan

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Résumé
Composition du Jury

Paul Apicella (Rapporteur)
Driss Boussaoud
Michèle Fabre-Thorpe
Jean-Michel Lassalle
Olivier Pascalis (Rapporteur)
Yves Rossetti (Rapporteur)
Paul-Antoine Salin
16 avril 2012

Séminaire

Making bilateral binaural

David Mcalpine
UCL Ear Institute. London (UK)

Lundi 16 avril 2012 · 14h Salle de conférence, Hôpital Purpan

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29 mars 2012

Séminaire

Visual and Vestibular Function in the Human Cingulate Sulcus

Professor Andrew Smith
Department of Psychology, Royal Holloway, University of London

Jeudi 29 mars 2012 · 11h Salle de conférence, Hôpital Purpan

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Résumé
The visual and vestibular systems are both involved in monitoring movement of the body through the environment (self-motion or egomotion). The processing of visual cues to egomotion (optic flow) has been associated primarily with cortical area MST, while vestibular processing of egomotion is less well understood but is often assumed to involve area PIVC. Using fMRI, we have recently identified a region in the human cingulate sulcus that has both visual and vestibular inputs and may be specialised for monitoring self-motion. I shall describe this area, which we refer to as CSv (cingulate sulcus visual area), and I shall present fMRI experiments involving visual and vestibular stimulation, both separately and together, that help to characterise the functions of area CSv.
20 mars 2012

Séminaire

The links between attention and visual awareness

Catherine Tallon-baudry
Laboratoire de Neurosciences Cognitives, INSERM-ENS U960, Paris

Mardi 20 mars 2012 · 14h30 Salle de conférence, Hôpital Purpan

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Résumé
Consciousness, as described in the experimental literature, is a multi-faceted phenomenon, that impinges on other well-studied concepts such as attention and control. Do consciousness and attention refer to different aspects of the same core phenomenon, or do they correspond to distinct functions? One possibility to address this question is to examine the neural mechanisms underlying consciousness and attention. If consciousness and attention pertain to the same concept, they should rely on shared neural mechanisms. Conversely, if their underlying mechanisms are distinct, then consciousness and attention should be considered as distinct entities. I will present here a series of experiments in which both attention and consciousness were probed at the neural level, that point toward a neural dissociation between the two concepts. I will present a new hypothesis on the links between attention and consciousness, the cumulative influence model, in which attention and consciousness correspond to distinct neural mechanisms feeding a single decisional process leading to behavior, and show how that this model accounts for available neural and behavioral data. In this view, consciousness should not be considered as a top-level executive function but should rather be defined by its experiential properties.
10 février 2012

Séminaire

Recording and stimulation of neural networks using microelectrode arrays

Blaise Yvert
INCIA Bordeaux

Vendredi 10 février 2012 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Microelectrode arrays (MEAs) have gained increasing interest for the exploration of neural networks (in vitro or in vivo) and the elaboration of neural prosthesis and implants for rehabilitation. These approaches offer unique ways to both record from and deliver electrical microstimulations to large neural ensembles. The performances of these approaches continuously gain from the miniaturization capabilities of microtechnology and microelectronics. Here, I will first expose simulation studies highlighting the effect of extracellular stimulation on neural elements and proposing new electrode configurations to improve the focalization of stimulations for building more efficient neural prosthesis. I will then present developments of high-density MEA systems based on integrated microelectronics and recent characterization of new microelectrode materials for improved neural recording and stimulation. The use of MEAs will be illustrated by a study aiming at characterizing rhythmic activity in the developing CNS.
2 février 2012

Séminaire

Decision Time for Free Will

Dr. Chris Olivola
Behavioural Science Group, Warwick Business School, University of Warwick, UK

Jeudi 2 février 2012 · 11h Salle de conférence, Hôpital Purpan

Affiche
6 janvier 2012

Séminaire

The Neural Basis of Rapid Categorization:
Linking Computational Models and Electrophysiology

Sébastien Crouzet
Brown University

Vendredi 6 janvier 2012 · 13h30 Salle de conférence, Hôpital Purpan

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2011 21
6 décembre 2011

Séminaire

Retro-attention:
triggering conscious perception after the stimulus is gone

Dr. Claire Sergent
Centre de Recherche de l\'Institut du Cerveau et de la Moëlle

Mardi 6 décembre 2011 · 14h30 Salle de conférence, Hôpital Purpan

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Résumé
Whether we become conscious of an external stimulus depends on initial parameters such as the strength of the external stimulation and our state of mind -in particular our attentional state- at the moment this external stimulation reaches our sensory receptor. So far it has not been explored whether conscious perception can also be influenced by late determinants, independently of the initial parameters.
I will present a serie of studies in which we show that attracting attention towards or away from the position where an single low-contrast stimulus has been presented several hundred milliseconds after it disappeared can still have a decisive impact on whether or not we become conscious of that stimulus.
These results suggest that conscious perception is not uniquely determined by the initial parameters at the moment of stimulus presentation and that post-stimulus manipulation of attention i.e. ?retro-attention? can have a causal role on whether a stimulus gains access to consciousness.
28 novembre 2011

Séminaire

Motion and form processing in visual perception:
independent or interacting ? Data from psychophysics, fMRI and MEG

Anne-lise Paradis
Centre de Recherche de l\'Institut du Cerveau et de la Moëlle - Équipe Cogimage

Lundi 28 novembre 2011 · 14h Salle de conférence, Hôpital Purpan

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26 octobre 2011

Séminaire

High-level Influences on Visual Perception

Jeroen Van Boxtel
UCLA

Mercredi 26 octobre 2011 · 16h Salle de conférence, Hôpital Purpan

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Résumé
When the brain is confronted with stationary ambiguous information, it has to resolve the visual conflict through some conflict resolution processes. In some cases several solutions are equally likely; the brain then lapses into indecision, and two (or more) solutions alternately reach awareness, an effect called visual rivalry. Investigating these processes allow us to get a window on how the visual brain forms our visual awareness. I used several types of visual rivalry, among which binocular rivalry. The origin of binocular rivalry has long been considered low-level (i.e. dependent on monocular neurons). In several separate studies I provide evidence for (1) a high-level (face) adaptation influence on rivalry; and (2) a new object-based type of rivalry independent of low-level visual conflict. Finally, I will talk about a paradigm that can show (3) the separate influences of endogenous attention and prior visual exposure on the subsequent formation of visual awareness. Each of these findings highlight separate influences of high-level visual processing on visual perception. Specifically, (1) the influence of feedback information from high to low levels, (2) a visual conflict resolution stage at high levels within the visual hierarchy, and (3) the influence of the cognitive process of endogenous attention on visual perception.
21 octobre 2011

Séminaire

Temporal dynamics of sensori-motor decisions

Aline Bompas
School of psychology, cardiff university

Vendredi 21 octobre 2011 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Neurophysiological and phenomenological data on sensorimotor decision making is growing so rapidly that it is now necessary and achievable to capture it in biologically inspired models, for advancing our understanding in both research and clinical settings. I will show how behavioural measures and brain imaging on saccadic decision can be used to question and constrain current models. I will address the integration of automatic and voluntary signals into sensorimotor decision, and discuss the particular case of free choice.
18 octobre 2011

Séminaire

Object recognition:
Tales from crowding, decoding, and EEG

Ramakrishna Chakravarthi

Mardi 18 octobre 2011 · 11h Salle de conférence, Hôpital Purpan

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10 octobre 2011

Séminaire

Probing the role of oscillatory brain activity in visual cortex excitability and visual perception using TMS and EEG

Gregor Thut
Dept of Psychology, University of Glasgow

Lundi 10 octobre 2011 · 15h30 Amphi Ducuing, Hôpital Purpan

Affiche
27 septembre 2011

Séminaire

Vers un langage commun de la perception et de l?action dans la communication parlée ?

Marc Sato
Responsable de l\'équipe \"Parole, Cerveau, Multimodalité, Développement\", Département Parole & Cognition, GIPSA-lab, UMR 5216 CNRS & Grenoble Université

Mardi 27 septembre 2011 · 11h Salle de conférence, Hôpital Purpan

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Résumé
Comment parvient-on à traiter le signal de parole pour extraire les invariants phonologiques et décoder la parole ? Plus de 50 ans après l?apparition de la théorie motrice de la perception de la parole, la mise en évidence des neurones miroir remet en cause l?idée d?une perception de parole purement auditive, suggère que le système moteur pourrait jouer un rôle dans la compréhension du langage, et, à tout le moins, impose de repenser les relations entre perception et action dans la communication parlée. Lors de cet exposé, aux vues d?études récentes et des résultats et non résultats obtenus, nous essaierons de mieux cerner ce que pourrait être un « langage commun de la perception et de l?action » dans la communication parlée.
23 septembre 2011

Séminaire

The neural and behavioral correlates of interference in feedforward and feedback processing

Dr Jacob Martin
Laboratory for Computational Cognitive Neuroscience, Georgetown University, Washington DC, USA

Vendredi 23 septembre 2011 · 11h Salle de conférence, Hôpital Purpan

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Résumé
The human visual system has an impressive ability to rapidly detect objects in complex natural scenes. This observation has led to computational models which explain how object detection can be accomplished by the human brain using only a single "feedforward pass;" starting from object representations in occipitotemporal cortex, and moving to task circuits in prefrontal cortex. We explored this hypothesis by performing psychophysical manipulations which indicated how behavioral performance can be improved by simply decreasing the expected amount of neural interference between closely temporally adjacent feedforward processes. Secondly, we investigated a challenge that feedforward theories fail to explain the Attentional Blink (AB), a phenomenon wherein, under RSVP conditions, the second (T2) of two targets (T1, T2) presented with a brief lag between them is often not detected. To do so, we performed high density human EEG experiments which tested the novel hypothesis that the AB can be caused by interference between the feedback signals triggered by the detection of T1, and the feedforward signals associated with T2. Using an RSVP EEG paradigm, we found that each subject's behavioral accuracy could be predicted based on the estimated magnitude of the interference between T1-associated feedback and T2-associated feedforward processing, resulting in a simple model of how the AB can arise as a consequence of signal interference at the perceptual level.
15 juin 2011

Séminaire

Causalité et coopération chez les primates

Odile Petit
Equipe Ethologie Evolutive, Institut Pluridisciplinaire Hubert Curien Département Ecologie, Physiologie et Ethologie UMR 7178

Mercredi 15 juin 2011 · 14h30 Salle de Conférence Pavillon Baudot, Hopital Purpan

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Résumé
Causalité et coopération chez les primates
Odile Petit
Équipe d?Éthologie Évolutive du Département Écologie, Physiologie et Éthologie
(UMR 7178 CNRS ? Université de Strasbourg) & Service d?Écologie Sociale de l?Université libre de Bruxelles

Dans le règne animal, de nombreux exemples de coopération ont été observés comme la formation de coalitions ou la chasse collective chez les primates. Étudier la coopération naturelle pose problème car ce sont des évènements rares. Pour pouvoir étudier les mécanismes sous-jacents à la coopération, une des solutions consiste à proposer aux animaux des tâches de coopération instrumentale. Ceci implique de considérer que les mécanismes impliqués dans la coopération naturelle sont similaires à ceux impliqués dans une tâche de coopération instrumentale. Nous avons soumis plusieurs groupes de primates à des expériences où il s?agissait de dissimuler de la nourriture sous des pierres trop lourdes pour être soulevées par un seul individu et qui nécessitaient l?action simultanée de deux ou plusieurs individus. Nous avons tenté de déterminer si le résultat commun n?impliquait aucune compréhension des actions et intentions du partenaire ou si les actions des différents participants résultaient de capacités cognitives développées et de la compréhension de relations de causalité. En effet, pour classer une action de coopération entre deux individus, quatre critères impliquant des capacités cognitives de plus en plus complexes sont distingués : la similarité, la synchronisation, la coordination et la collaboration. Cependant, l?ensemble de ces critères n?est pas systématiquement atteint pour chaque cas de coopération. C?est pourquoi, dans une autre série d?expériences, nous avons évalué la capacité qu?ont des primates non anthropoïdes de raisonner, c?est-à-dire leur capacité à percevoir leur environnement et à faire des inférences entre différents éléments du milieu dans lequel ils évoluent, afin de prendre des décisions et de se comporter de manière adaptée. Cette seconde série d?expériences nous a permis d?évaluer les capacités de compréhension causale et de raisonnement de ces différentes espèces sur certaines propriétés physiques des objets et de leur environnement et de lier ces résultats aux capacités nécessaires à la réalisation de la tâche de coopération instrumentale décrite ci-dessus.
25 mai 2011

Séminaire

Monkey fMRI :
toward applications in translational neurosciences

Bechir Jarraya
Head of Inserm Avenir Bettencourt Schueller Lab, Neurospin, CEA Paris

Mercredi 25 mai 2011 · 14h Salle Conference Pavillon BAUDOT, Hôpital Purpan

Affiche
20 mai 2011

Séminaire

Rules Were Made to be Broken:
Multisensory Interactions at Two Stages of Cortical Processing

Ian Fiebelkorn
Albert Einstein College of Medicine, New York

Vendredi 20 mai 2011 · 11h Salle de réunion E2, Hôpital Purpan

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19 mai 2011

Séminaire

Ideas about the role of cortical oscillations in speech and language processing

Anne-lise Giraud
Laboratoire de Neurosciences Cognitives- DEC Ecole Normale Supérieure. Paris

Jeudi 19 mai 2011 · 14h Amphi Ducuing, Hôpital Purpan

Affiche
21 avril 2011

Séminaire

Saccade-sequence planning and perception of visual space

Louisa Lavergne
LPNCog (Boulogne-Billancourt)

Jeudi 21 avril 2011 · 11h30 autre, Hopital Purpan

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18 avril 2011

Séminaire

The extent that information can be processed from unconsciously perceived faces

Ido Amihai
Hebrew University of Jerusalem

Lundi 18 avril 2011 · 14h30 Salle de Reunion, Baudot, Hopital Purpan

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18 avril 2011

Séminaire

Acoustic Experience Alters How You See the World

Dr Steve Lomber
Centre for Brain and Mind. The University of Western Ontario (Canada)

Lundi 18 avril 2011 · 11h Bibliothèque de neurologie, pavillon Riser, Inserm, Hopital Purpan

Affiche
15 avril 2011

Séminaire

Unseen complex motion is modulated by attention and generates a visible aftereffect

Lisandro Kaunitz
University of Trento

Vendredi 15 avril 2011 · 10h30 Salle de Reunion, Baudot, Hopital Purpan

Affiche
12 avril 2011

Séminaire

The operating regime of local computations in primary visual cortex

Marcel Stimberg
TU Berlin

Mardi 12 avril 2011 · 10h30 Salle de Reunion, Baudot, Hopital Purpan

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11 avril 2011

Séminaire

Une approche translationnelle de la physiopathologie des Troubles obsessionnels compulsifs

Pierre Burbaud & Dominique Guehl
Institut des maladies Neurodégénératives UMR 5293

Lundi 11 avril 2011 · 14h30 Salle des Thèses, Faculte de medecine de Rangueil

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Résumé
Une approche translationnelle de la physiopathologie
des troubles obsessionel-compulsifs

P. Burbaud et D. Guehl


oLe doute est un processus métacognitif qui influence fortement nos prises de décisions. Il devient pathologique lorsqu’il envahit l’ensemble du champ mental comme dans les troubles obsessionnel-compulsifs (TOC), une pathologie psychiatrique qui touche 2 à 3% de la population. Nous nous sommes intéressés dans ce travail aux bases neuronales sous-tendant le doute et les comportements de vérification.
oNous avons développé une tâche cognitive (CT) s’inspirant d’un « matching-to-sample task » dans laquelle le sujet a la possibilité illimitée de vérifier ses choix avant de prendre une décision. Nous avons pu montrer que les performances comportementales dans la CT étaient liées au statut du sujet (TOC vérificateur ou non, sujet témoin), à la complexité des associations d’image (similaires, différentes) et au degré d’incertitude (nombre de vérifications). L’étude du substratum anatomo-fonctionnel de ces comportements en IRMf, nous permis de montrer: 1) une corrélation entre doute et activité orbitofrontale (COF) avec une absence de modulation chez les patients TOC lors des prises de décision précédant une vérification ou suivant une erreur, 2) une augmentation excessive de l’activité du cortex cingulaire antérieur (CCA) après un feedback positif chez les patients présentant un TOC, en faveur d’un contrôle excessif de l’action, 3) une diminution de l’activité du noyau caudé après un feedback positif, signant une diminution de sensibilité aux renforcements positifs. La même tâche (CT) a été ensuite utilisée pour la réalisation d’enregistrements unitaires en per-opératoire dans la région associativo-limbique du noyau sous-thalamique (NST) chez des patients TOC candidats à une stimulation cérébrale profonde. Nous avons observé que les neurones du NST associatif modifiaient leur activité en rapport avec des informations de nature polymodale (instruction, mouvement, feedback), en accord avec le modèle de convergence du traitement des informations au sein des ganglions de la base. Par ailleurs, la fréquence de décharge des neurones du NST était clairement prédictive du comportement de vérification suggérant que cette région joue un rôle dans le maintien à la conscience des pensées ou actions répétitives. Nous poursuivons actuellement cette approche en réalisant des enregistrements intra-cérébraux (« local field potentials ») chez des patients TOC et des patients épileptiques porteurs d’électrodes intra-cérébrales.
oDans une seconde étude menée chez le singe, nous avons tenté de réaliser un modèle de TOC chez le primate en pratiquant des manipulations pharmacologiques in-situ des relais thalamiques des projections vers le COF et le CCA. Nous avons observé que des injections de bicuculline : 1) au niveau du noyau ventral antérieur (VA) provoquait des comportements de recherche fine de nourriture et de toilettage, proches de compulsions, 2) au niveau du noyau médio-dorsal des signes d’anxiété majeure avec manifestations neurovégétatives. Par ailleurs, des injections de muscimol au niveau du VA induisaient des comportements hyperactifs. Ces données plaident pour un dysfonctionnement des projections thalamo-frontales dans les composantes comportementales et émotionnelles associées au TOC.
oAu total, le développement de nouvelles stratégies thérapeutiques dans le traitement des TOC doit passer par une meilleure connaissance de leur physiopathologie. Nos résultats confortent l’idée d’une implication forte des boucles associatives et limbiques unissant les ganglions de la base et le cortex préfr
24 mars 2011

Séminaire

Face representation explored with fMRI in monkeys

Fadila Hadj-bouziane
INSERM U864, Espace et Action - Equipe AVENIR �Espace Multisensoriel et Action� (Bron)

Jeudi 24 mars 2011 · 14h Salle du Conseil, Faculte de medecine de Rangueil

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Résumé
Au premier coup d'�il, hommes et macaques sont capables de d�terminer � la fois l'identit� d'un de leur cong�n�re et son �tat �motionnel. Cette capacit� remarquable du cerveau � traiter les informations contenues dans les visages est, pour ces deux esp�ces, essentielle pour faire face � la complexit� de leur vie sociale. L'�lectrophysiologie chez le singe, et l�IRMf chez l�homme ont r�v�l�, respectivement, l�existence de neurones et de r�gions s�lectifs des visages. Chez les patients, des l�sions incluant le gyrus fusiforme, produisent une difficult� sp�cifique � reconna�tre des visages familiers (prosopagnosie). Ces donn�es sugg�rent l'existence d'un r�seau c�r�bral sp�cialis� dans le traitement des visages chez les primates. Reste aujourd'hui � comprendre comment sont repr�sent�s les visages dans le cerveau et comment ce r�seau assure la perception des caract�ristiques fondamentales du visage, li�es � l'identit�, versus la perception des modifications des aspects du visage, li�es entre autres aux expressions faciales. Pour aborder cette question, nous avons combin� l'�tude des activations et de la connectivit� fonctionnelle r�v�l�es par l'IRMf chez le singe avec les techniques invasives possibles chez cette esp�ce: les enregistrements unitaires et les l�sions exp�rimentales, irr�versibles et r�versibles. Nos donn�es apportent 1) sur le plan fondamental, l'une des rares preuves du r�le crucial de l�amygdale et des r�gions s�lectives aux mouvements dans le traitement par le cortex temporal des �motions v�hicul�es par les visages et d'un lien entre signal IRMf et potentiels d'action, et 2) r�v�lent, sur le plan physiopathologique, le r�seau fonctionnel sous-tendant la perception des visages, et son alt�ration dans la prosopagnosie.
15 février 2011

Séminaire

Neuronal responses during and after the presentation of prolonged stationary visual stimuli:
implications and insights from visual illusions.

Douglas Mclelland
Department of Physiology, Anatomy and Genetics, University of Oxford

Mardi 15 février 2011 · 11h Salle des Thèses, Faculte de medecine de Rangueil

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Résumé
Prolonged static visual stimuli have largely been neglected in electrophysiological studies of the visual system. On the other hand, these same stimuli have given rise to a rich psychophysical literature because of the intriguing percepts they generate, including fading, negative afterimages, and complementary motion afterimages. These studies could provide important insights into the normal activity of the visual system, but have suffered from the lack of a physiological basis for interpretation. I will present our recent characterisation of the activity of cells in LGN and V1 of the anaesthetised macaque, both during and after the prolonged presentation of static stimuli. These results yield insights into the mechanisms underlying several visual illusions, and in turn, raise intriguing questions about the basic operation of the visual system.
20 janvier 2011

Séminaire

Neural coding of computational factors affecting decision making

Dr. Jean-claude Dreher
Centre de Neurosciences Cognitives, Lyon

Jeudi 20 janvier 2011 · 14h Salle des conférences, Faculte de medecine de Rangueil

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Résumé
When facing a choice between several options, recent neuroimaging approaches on value-based decision-making assume that the brain computes the subjective value of outcomes expected from alternative options, weighing the likely benefits and costs resulting from an action. We recently used standard models of utility to investigate how evaluation of different type of costs (delay and effort) as well as reward probability and uncertainty influence brain response using fMRI in healthy controls and intra-cranial recordings in patients with epilepsy. Our neuroimaging data reveal that the human brain uses distinct valuation subsystems for different types of costs, reflecting in opposite fashion delayed reward and future energetic expenses. We also investigated common and specific brain regions responding to experienced value for different types of rewards, comparing brain responses for primary (erotic stimuli) and secondary rewards (money). Our results showed both a core reward system processing experienced value regardless of reward type and a functional organization in the orbitofrontal cortex along a postero-anterior axis according to reward type, with the anterior part responding exclusively to money and the posterior and medial part responding exclusively to erotic stimuli. In addition, we recently showed that genetically-influenced variations in dopamine transmission modulate the response of brain regions involved in anticipation and reception of rewards, and also provided evidence of neurofunctional modulation of the reward system by gonadal steroid hormones in humans. These findings establish a neurobiological foundation for understanding the impacts of genes and gonadal steroids hormones modulating dopamine transmission on vulnerability to drug abuse and neuropsychiatric diseases. Together, these results indicate that the combination of computational approach, molecular genetics, endocrinology and neuroimaging now helps understanding basic biological mechanisms underlying reward processing.
2010 23
16 décembre 2010

Séminaire

Psychophysique visuelle et oculomotrice de la lecture avec déficience maculaire

Eric Castet
INCM, Marseille

Jeudi 16 décembre 2010 · 11h salle des thèses, Faculte de medecine de Rangueil

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Résumé
En France, environ 1 million de personnes souffrent de Dégénérescence Maculaire Liée à l’Age (DMLA), une rétinopathie qui induit un scotome absolu ou relatif dans le centre du champ visuel. Les conséquences perceptives les plus prononcées pour ces patients sont essentiellement une difficulté ou une impossibilité à lire du texte et des problèmes de reconnaissance des visages.
Mes travaux se focalisent sur les performances de lecture de ces patients avec une approche psychophysique. Deux types d’études sont menés en parallèle soit sur des patients DMLA soit sur des sujets sans pathologie immergés dans un simulateur de malvoyance. Je présenterai quelques résultats récents qui montrent l’intérêt de combiner des recherches cliniques avec des recherches sur simulateur. Je présenterai finalement les travaux en cours sur le développement d’un système de vision augmentée asservie au regard dont l’objectif final est d’améliorer les performances perceptives des patients DMLA.
8 décembre 2010

Séminaire

Cortical neurons in neurovascular and neurometabolic coupling

Bruno Cauli
Laboratoire de Neurobiologie des Processus Adaptatifs UMR 7102 CNRS-UPMC Paris

Mercredi 8 décembre 2010 · 11h salle des Thèses, Faculte de medecine de Rangueil

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Résumé
Tight coupling between neuronal activity, local cerebral blood flow and metabolism is at the basis of contemporary brain imaging techniques, largely used to infer neuronal activity in health and disease. In the cerebral cortex, the hemodynamic response triggered by neuronal activity involves the release of various vasoactive messengers synthesized and released by different cell types including neurons and astrocytes. These hemodynamic changes are followed by a transient rise in lactate flux, extracellular glucose levels remaining fairly constant. Despite this physiopathological importance the cellular and molecular mechanisms, or even the functional consequences, of neurovascular and neurometabolic coupling are poorly understood.
Several Glutamatergic and GABAergic neurons produce vasodilatory and/or vasoconstricting substances and are likely to account, at least partially, for the complex spatiotemporal hemodynamic response. However the large diversity of cortical neurons in the cerebral cortex makes it difficult to study their function(s) in neurovascular coupling. We sought to classify systematically cortical neurons allowing us to identify and to characterize different neuronal types potentially involved in neurovascular coupling. We showed that the activation of some of these neuronal types evoked vascular responses. These vasomotor neurons were dilating if they expressed type 2 cyclo-oxygenase, VIP or nNOS and constricting if they expressed somatostatin or NPY.
To evaluate further the physiological consequences of changes in energy supply, we studied the influence of metabolic environments on neuronal activity, focusing on ATP sensitive K+ (KATP) channels. By coupling energy states with membrane potential these hyperpolarizing channels act as metabolic sensors. We observed that the vast majority of cortical neurons expressed functional KATP channels composed of Kir6.2 and SUR1 subunits. Using perforated patch recordings, which preserve intracellular metabolism, we found that an increased energy supply via glucose had little or no effect on neuronal activity. In contrast, increased energy supply via lactate doubled the evoked firing rate of neurons. We demonstrated that lactate-sensing in cortical neurons was mediated by lactate uptake and KATP channel closure. These results indicate that under physiological conditions cortical neurons prefer to metabolize lactate. The lactate-sensing of cortical neurons also suggests that negative feedback mechanisms might be recruited to prevent an explosive enhancement of neuronal activity by lactate supply.
18 novembre 2010

Séminaire

Quantitative analysis of 3D cerebral images in anatomical and functionnal MRI

Laurent Risser
Biomedical Image Analysis (BioMedIA) Group and Institute for Mathematical Sciences, Imperial College, London

Jeudi 18 novembre 2010 · 11h salle du Conseil, Faculte de medecine de Rangueil

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Résumé
Two different topics will be disussed during this talk, both of them being related to the quantitative analysis of 3D cerebral images:

(1) Toward fine models for the quantitative analysis of the cerebral activity in fMRI.
I will first present a model for the analysis of the cerebral activity in BOLD fMRI. Standard models make the hypothesis that the dynamic of
oxygen consumption is homogeneous in the brain, although this consumption is obviously highly variable from a cortical area to another. Moreover, spatial smoothing of the images is performed in order to improve the signal to noise ratio. This however also leads to a loss of local activations and spatial accuracy in general. I will then present a model making finer hypotheses on the observed signal and discuss the gain of sensitivity it provides on clinical images.

(2) Computational anatomy for the temporal analysis of the early brain development from MR images
Computational anatomy (CA) is a mathematical formalism dedicated to the comparison of shapes with an unpreceded descriptive power. Although its mathematical foundations are well established, successful applications of this formalism on 3D images are very recent. After presenting the formalism, I will discuss its application to the anatomical analysis of the early brain development. 30 MR images were images acquired on pre-term babies between 30 and 40 weeks of gestational age. These images allowed us to build a model of the average cortical growth and its variability. I will then discuss our current results, and focus on the notion of scale at which the anatomical changes are observed.
21 octobre 2010

Séminaire

Le séminaire sera reprogrammé.

Eric Castet (annule En Raison Des Greves)
INCM, Marseille

Jeudi 21 octobre 2010 · 11h Petit Amphi Physiologie Bat A2 RDC, Faculte de medecine de Rangueil

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20 octobre 2010

Séminaire

Soutenance de thèse

Zoé Massida
CerCo

Mercredi 20 octobre 2010 · 14h Salle de séminaire de l\'IBCG, Universite Paul Sabatier

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Résumé
"Étude de la perception de la voix chez le patient sourd postlingual implanté cochléaire unilatéral et le normo-entendant en condition de simulation d'implant. Psychophysique et imagerie."
Jury
Directeur de thèse : Pascal Barone
Co-directeur de thèse : Olivier Deguine
Rapporteure : Nicole Bruneau
Rapporteur : Daniel Pressnitzer
Examinateur : Eric Truy
Examinateur : Pascal Belin
Examinateur : Pier-Giorgio Zanone
13 octobre 2010

Séminaire

Investigations into the neural basis of recognition memory

Malcolm W. Brown
MRC Centre for Synaptic Plasticity, University of Bristol

Mercredi 13 octobre 2010 · 11h Salle des thèses, Faculte de medecine de Rangueil

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28 septembre 2010

Séminaire

"Disparity Processing in Human Visual Cortex using High-density EEG "

Benoit Cottereau
The Smith-Kettlewell Eye Research Institute

Mardi 28 septembre 2010 · 14h Salle des Thèses, Faculte de medecine de Rangueil

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22 septembre 2010

Séminaire

How auditory information influences binocular rivalry:
Revisiting the McGurk effect

Manuel Vidal
Laboratoire de Physiologie de la Perception et de l’Action, Collège de France

Mercredi 22 septembre 2010 · 16h Amphi DAURAT, Bâtiment U3, Universite Paul Sabatier

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Résumé
Although multistable perception has long been studied, in recent years, paradigms involving ambiguous visual stimuli have been used to assess phenomenal awareness. Indeed, for such stimuli, although the sensory input is invariant, a perceptual decision occurs bringing to awareness only one of the possible interpretations. Moreover, the observer experiences inevitable oscillations between these percepts. Only few studies have tackled bistability for multimodal percepts. Hupé et al. [1] used spatially located audio-visual beeps and failed in finding synchronized auditory and visual perceptual decisions. Van Ee et al. [2] investigated how sensory congruency could influence volitional control in binocular rivalry using looming motion stimuli that could be seen, heard or sensed on the hand. They found that attention to the additional modality (sound or touch) has to be engaged to promote visual dominance and that only temporal congruency is required in the end. Nonetheless, we believe that in both studies such low-level stimuli could have reduced the possibility of finding passive interactions and limited the congruency to temporal features, which motivated the use of higher-level audio-visual verbal processing in our experiments. In a clever dynamic version of the classical face/vase illusion, Munhall et al. [3] found no interaction between the suppressed percept (the talking faces) and sound. Based on known differences between ambiguous figures and rivalry, we wondered if the use of rivaling talking faces could increase the sensory integrations with the suppressed percept.
Accordingly, we developed a series of experiments relying on the McGurk effect – known to involve robust audio-visual integration – in order to investigate multimodal rivalry. After validating the bistability properties of rivaling videos (lips pronouncing /aba/ vs. /aga/), we added the sound /aba/ in order to assess the influence of audio-visual integration in the perceptual decision process. The results evidence, on the one hand, possible multimodal integration with the suppressed visual stimulus and, on the other hand, the influence of consistent auditory stimulation in the dominance mechanism of visual rivalry. These findings suggest that at higher-level processing stages, auditory cues do interact with the perceptual decision involved in binocular rivalry. This research project will eventually shed light on the locus where multimodal oscillations might occur, feeding the historical debate of whether perceptual decisions take place in early processing stages or can be top-down driven.

References:
1.Hupe, J., Joffo, L. & Pressnitzer, D. Bistability for audiovisual stimuli: Perceptual decision is modality specific. J.Vis. 8, 1-15 (2008)
2.van Ee, R., van Boxtel, J.J.A., Parker, A.L. & Alais, D. Multisensory congruency as a mechanism for attentional control over perceptual selection. J. Neurosci 29, 11641-11649 (2009)
3.Munhall, K., ten Hove, M., Brammer, M. & Paré, M. Audiovisual Integration of Speech in a Bistable Illusion. Current Biology 19, 735-739 (2009)
4. McGurk, H. & MacDonald, J. Hearing lips and seeing voices. Nature 264, 746-748 (1976)
20 septembre 2010

Séminaire

On the relationship between motor and perceptual behavior - an SDT framework

Andrei Gorea
Laboratoire Psychologie de la Perception, CNRS & Paris Descartes University

Lundi 20 septembre 2010 · 16h Salle du Conseil, Faculte de medecine de Rangueil

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Résumé
Starting with Goodale & Milner’s (1992) neuropsychological observations, a large number of neuropsychological and psychophysical studies has documented a putative dissociation between perception and action. However, a closer inspection of this literature reveals a number of methodological and conceptual shortcomings. I shall present a series of experiments making use of a variety of psychophysical techniques designed to gauge the relationship between, on the one hand, Reaction Times and Saccade and Hand pointing biases and, on the other hand, observers’ perceptual states as assessed for close to threshold (masked – metacontrast – and not-masked) stimuli via Yes/No paradigms. All these studies reveal a strong motor-perceptual state correlation indicating that motor and perceptual responses are based on a unique internal response. A one-path-two-decisions stochastic race model drawing on standard Signal Detection Theory provides a fair account of some of the data, hence overruling the necessity of a model with dual processing of visual stimulation.
6 juillet 2010

Séminaire

Control of stopping oculomotor plan in human and monkey

Dr. Pierre Pouget
CRICM, Hopital de la Salpetriere, Paris

Mardi 6 juillet 2010 · 11h Salle de theses, Faculte de medecine de Rangueil

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8 juin 2010

Séminaire

De la nature et de la spécificité des mécanismes de reconnaissance des visages:
ce que nous apprend la prosopagnosie

Thomas Busigny
Université de Louvain la Neuve

Mardi 8 juin 2010 · 11h Salle des thèses, Faculte de medecine de Rangueil

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7 juin 2010

Séminaire

Topography of connections of single digit tip representations in the primate somatosensory cortex

László Négyessy
Neurobionics Research Group, Hungarian Academy of Sciences - Peter Pazmany Catholic University - Semmelweis University, Budapest

Lundi 7 juin 2010 · 16h salle des thèses, Faculte de medecine de Rangueil

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Résumé
Primate fingertips are specialized for gripping, grasping, haptic exploration, and manipulation. To
understand these functions it is essential to explore the interactions between functional fingertip
representations in the somatosensory cortex. To this end, we used optical imaging and tract tracing
techniques to map the intrinsic connections of the fingertip representation regions of area 3b in addition to
the extrinsic connections between areas 3b with other somatosensory cortical regions including areas 1, 2
and 3a of the squirrel monkey. In area 3b, the injection of tracers resulted in a dense labeling of neurons and
axonal fibers around the injection site covering the injected fingertip region as inferred from the optical
imaging maps. Outside the region of homogenous labeling around the injection site, anterograde and
retrograde labeling exhibited a patchy distribution both within area 3b and the other somatosensory cortical
regions. Within area 3b patchy labeling was distributed anisotropically, preferentially in a mediolateral
direction. This pattern of labeling was accompanied by a similar mediolateral orientation of long range
axonal fibers within area 3b. Another bundle of long range fibers connected area 3b with clusters of labeled
neurons and terminal axon arborizations in areas 1 and 2. These clusters appeared to overly representations
of the injected digit. The number of neurons and axon terminal-like structures were highest within patches of
the supragranular layers. However, a lower density of bouton-like structures were found in regions lacking
significant retrograde and anterograde labeling. In summary, within area 3b, the mediolateral pattern of
labeling is consistent with a preferential interaction between neighboring fingertip regions rather than within
single finger representations (i.e. along a single digit) and could be responsible for integration of interdigit
functions such as the funneling illusion. Furthermore, the specificity of inter-areal connectivity supports the
presence of a functional network useful for digit coordination during fine exploration and manipulation.
1 juin 2010

Séminaire

Fast visual processing of objects, faces, and natural scenes, and how it is affected by ageing.

Guillaume Rousselet
Centre for Cognitive Neuroimaging, University of Glasgow

Mardi 1 juin 2010 · 11h salle des thèses, Faculte de medecine de Rangueil

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28 mai 2010

Séminaire

"Early perception-action cycles in binocular vision:
Cortical architectures for 3D dynamic measurements in the peripersonal space"

Silvio Sabatini
Département d\\\'ingénierie biophysique et électronique. Université de Gènes.

Vendredi 28 mai 2010 · 11h Salle de conférence, Faculte de medecine de Rangueil

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25 mai 2010

Séminaire

Attentional modulation by a parietal priority map

Fabrice Arcizet
UCLA, Department of Neurobiology

Mardi 25 mai 2010 · 11h salle des Thèses, Faculte de medecine de Rangueil

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22 avril 2010

Séminaire

Recognition and learning of complex sounds

Trevor Agus, Clara Sueid & Daniel Pressnitzer
Equipe Audition, Département d\'études cognitives, Ecole normale supérieure, Paris

Jeudi 22 avril 2010 · 11h Petit Amphi de Physiologie (bat. A2 fac de médecin, Faculte de medecine de Rangueil

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9 avril 2010

Séminaire

Hierarchical organisation of voice and voice gender perception

Ian Charest
Department of Psychology, University of Glasgow

Vendredi 9 avril 2010 · 11h Salle du Conseil, Faculte de medecine de Rangueil

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8 avril 2010

Séminaire

From Macroscopic to Microscopic - Interpreting population spiking activity from non-invasive EEG

Kevin Whittingstall
Max Planck Institute for Biological Cybernetics

Jeudi 8 avril 2010 · 11h Salle du Conseil, Faculte de medecine de Rangueil

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2 avril 2010

Séminaire

HDR - Dynamique et mécanismes des réponses neuronales dans le cortex visuel

Lionel Nowak
CerCo

Vendredi 2 avril 2010 · 14h Amphi Schwartz (Inst Mathématiques, UPS bat. 1R3), Universite Paul Sabatier

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31 mars 2010

Séminaire

Smarter than we think:
Conflict monitoring during decision-making

Dr. Wim De Neys
Laboratoire Cognition, Langues, Langage, Ergonomie (CLLE) CNRS, Université de Toulouse Mirail

Mercredi 31 mars 2010 · 11h Salle des Thèses, Faculte de medecine de Rangueil

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2 mars 2010

Séminaire

Synchronization dynamics in human visual perception

Eugenio Rodriguez
Université Catholique du Chili - Max-Plack for Brain Research.

Mardi 2 mars 2010 · 11h salle des thèses, Faculte de medecine de Rangueil

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Résumé
Synchronization dynamics in human visual perception
During visual perception, largely distributed neural activity self organizes into coherent perception. It has been proposed that neural synchronization can be an operative factor in this self organization process. Here I will present arguments and show several experiments supporting the participation of neural synchrony in visual perception. I will argue that neural synchrony can be found (a) in very different brain structures, (b) trough a large range of the phylogenetic scale (c) at several levels of neural organization and (d) that it increases the probability of activity propagation. All these characteristics should be present in a mechanism for neural coordination (1). Furthermore, in our experiments, we have found that spike synchrony is present in the visual cortex of monkeys freely viewing natural images 30 to 90 ms after fixation onset. This synchronization is absent when monkeys are looking at a black display (2). In humans Large-Scale Neural Synchrony is present when subjects recognize a face in an ambiguous picture but not when they only see meaningless shapes (3). Large-Scale Neural Synchrony also correlates with conscious visual perception but not with subliminal perception (4). Abnormal visual perception and visual working memory in schizophrenia correlates with reduced Neural Synchronization (5) and lack of synchrony modulation (6) respectively. Finally Neural synchronization increases from childhood to adulthood in a way that parallels the maturation of visual perception (7). Taken together, this evidence supports the participation of neural synchrony in the organization of visual perception.

(1)Varela F, Lachaux JP, Rodriguez E, Martinerie J. The brainweb: phase synchronization and large-scale integration. Nat Rev Neurosci. 2001 Apr;2(4):229-39.
(2)Maldonado P, Babul C, Singer W, Rodriguez E, Berger D, Grün S. Synchronization of neuronal responses in primary visual cortex of monkeys viewing natural images. J Neurophysiol. 2008 Sep;100(3):1523-32.
(3)Rodriguez, E., George, N., Lachaux, JP., Martinerie, J., Renault, B., & Varela,F. Perception's shadow: Long-distance synchronization of human brain activity. Nature 397, 430-433 (1999).
(4)Melloni L, Molina C, Pena M, Torres D, Singer W, and Rodriguez E. (2007) Synchronization of Neural Activity across Cortical Areas Correlates with Conscious Perception. J. Neurosci. March 14, 2007 • 27(11):2858 –2865.
(5)Uhlhaas P, Linden D, Singer W, Haenschel C, Lindner M, Maurer K, & Rodriguez E.
Dysfunctional Long-Range Coordination of Neural Activity During Gestalt Perception in Schizophrenia. J. Neurosci. 2006; 26 8168-8175
(6)Haenschel C, Bittner RA, Waltz J, Haertling F, Wibral M, Singer W, Linden DE, Rodriguez E. Cortical oscillatory activity is critical for working memory as revealed by deficits in early-onset schizophrenia. J Neurosci. 2009 Jul 29;29(30):9481-9.
(7)Uhlhaas PJ, Roux F, Singer W, Haenschel C, Sireteanu R, Rodriguez E. The development of neural synchrony reflects late maturation and restructuring of functional networks in humans. Proc Natl Acad Sci U S A. 2009 Jun 16;106(24):9866-71.
23 février 2010

Séminaire

From Percepts to Recollections:
Insights from single neuron recordings in the human temporal lobe

Itzhak Fried, Md, Phd
Cognitive Neurophysiology Laboratory, UCLA Medical Center, Los Angeles

Mardi 23 février 2010 · 11h Salle des Conférences, 1er étage du Bâtiment admin, Faculte de medecine de Rangueil

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27 janvier 2010

Séminaire

Analyse des écoulements micro-vasculaires cérébraux

Romain Guibert
Institut de Mécanique des Fluides de Toulouse

Mercredi 27 janvier 2010 · 11h salle des Thèses, Faculte de medecine de Rangueil

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Résumé
Ces travaux s'intéressent à la micro-hydrodynamique des écoulements sanguins cérébraux dans les réseaux micro-vasculaires. A partir d'images tridimensionnelles haute résolution obtenues par micro-tomographie, les réseaux micro-vasculaires sont numérisés après différentes étapes de traitement d'images. Une résolution numérique approchée des écoulements sanguins quasi-statique de type réseau est développée. Cette approche permet à la fois de prendre en compte la structure géométrique micro-vasculaire complexe et les interactions hydrodynamiques non-locales des hématies confinées qui s'écoulent en son sein. La méthode proposée permet l'évaluation des distributions de pression, d'hématocrite et de débit sur des volumes cérébraux d'une dizaine de millimètres cube où quelques dizaines de milliers de segments vasculaires sont présents. L'analyse systématique des modèles de rhéologie sanguine existant montrent la prépondérance du choix du modèle de viscosité, à opposer au faible impact de la séparation de phase sur l'écoulement, phénomène pour lequel nous proposons aussi une modélisation alternative. De plus, nous avons analysé la perfusion sanguine cérébrale, et l'organisation générale des écoulements corticaux. Dans la situation physiologique normale, nous quantifions les territoires vasculaires qui sont les unités fonctionnelles micro-vasculaires. Nous évaluons leur évolution et leur robustesse dans des contextes pathologiques modèles et notamment pour les micro-accidents vasculaires cérébraux.