FENS workshop on Dyanmic aspects of brain functions: methodologies, comcepts, models
December 8-16, 2002 - 2002 - Kitzbuhel, Austria
 
Brain synchronization events follow cognitive challenges
 
A. Delorme, S. Makeig
 

Swartz Center fo Computational Neuroscience, INC, UCSD, San Diego, CA, USA

arno@salk.edu, scott@salk.edu

 
    Non-invasively recorded high-density EEG data contain a large amount of information about cortical synchronization in multiple frequency bands and cortical domains. Sufficient signal processing means to detect, visualize and model these phenomena are now being developed. The approach I present here uses independent component analysis to separate EEG information from different domains of cortical synchrony and to remove artifacts, followed by time/frequency analysis and single-trial visualization, to detect brain dynamic events occuring in response to cognitive challenges presented by external events. A class of such events are coherent theta band bursts that briefly organize synchronous brain activity within otherwise-independent cortical domains in response to cognitive challenges. I give examples from EEG responses to task-relevant stimuli in stimulus detection, visual selective attention and Erickson flanker tasks. I show, in particular, that theta dynamic events underlie the error-related negativity (ERN) following errors committed in forced choice responses under time pressure. Source location estimates of the EEG domains linked by these dynamic events suggest they form transient fronto-parietal networks that may serve to regulate top-down attentional re-tuning of motor and perceptual brain areas in light of the perceived significance of error events.