EEG phase synchronization and information flow during audio-visual stimulation

Phase synchronization and directionality of human EEG data recorded under influence of audio-visual stimulation were investigated. EEG data came from 6 healthy volunteers repeatedly exposed to 20 min stimulation that comprised intervals with steady stimulation at 4 and 17 Hz. Entrainment of the brain waves and phase synchronization both significantly increased during the stimulation in comparison to nonstimulating conditions accross the whole cortex. Positive correlation of entrainment and phase synchronization was obtained. Directionality analysis suggests that applied methods may estimate direction of information flow from visual processing centers towards frontal cortex locations.