EEG principal component organization via time-frequency representationEEG principal component organization via time-frequency representation Διπλωματική Εργασία 2014-03-242009enOver the past few years there has been an increased interest in studying the underlying neural mechanism of cognitive brain activity related to memory. In this direction, we study the brain activity based on its independent components instead of the EEG signal itself aiming towards identifying and analyzing induced responses being attributed to oscillatory bursts from local or distant neural assemblies, with variable latency and frequency, in an auditory working memory paradigm. The significance of the components is determined via intertrial coherence measures. The contribution and functional coupling of independent components to evoked and/or induced oscillatory activities is investigated through the concept of the recently introduced partial directed coherence method, which can also reveal the direction of the statistically significant relationships. The results on real data from an oddball experiment are in accordance with previous psychophysiology studies suggesting increased phase locked activity most prominently in the delta/ theta band, while alpha is also apparent in measures of non phase-locked activity. Dynamic synchronization is inferred between the alpha and delta bands, whereas some influence of the theta band is also detected. This study indicates that functional connectivity during cognitive processes may be successfully assessed using spectral power measures applied on independent components, which reflect distinct spatial patterns of activity.http://creativecommons.org/licenses/by/4.0/Πολυτεχνείο Κρήτης::Τμήμα Ηλεκτρονικών Μηχανικών και Μηχανικών ΥπολογιστώνIordanidou_Vasiliki_Dip_2009.pdfChania [Greece]Library of TUC2014-03-24application/pdfN/Ahttp://www.library.tuc.gr/artemis/DT2009-0170/DT2009-0170.pdffree Iordanidou Vasiliki Ιορδανιδου Βασιλικη Zervakis Michail Ζερβακης Μιχαηλ Technical University of Crete Πολυτεχνείο Κρήτης ΔΙΠ2217