PRESTIMULUS EEG MICROSTATES INFLUENCE VISUAL EVENT-RELATED POTENTIAL MICROSTATES IN-FIELD MAPS WITH 47 CHANNELS

The influence of the immediate prestimulus EEG microstate (subsecond e poch of stable topography / map landscape) on the map landscape of vis ually evoked 47-channel event-related potential (ERP) microstates was examined using the frequent, non-target stimuli of a cognitive paradig m (12 volunteers). For the two most frequent prestimulus microstate cl asses (oriented left anterior-right posterior and right anterior-left posterior), ERP map series were selectively averaged. The post-stimulu s ERP grand average map series was segmented into microstates; 10 were found. The centroid locations of positive and negative map areas were extracted as landscape descriptors. Significant differences (MANOVAs and t-tests) between the two prestimulus classes were found in four of the ten ERP microstates. The relative orientation of the two ERP micr ostate classes was the same as prestimulus in some ERP microstates, bu t reversed in others. - Thus, brain electric microstates at stimulus a rrival influence the landscapes of the post-stimulus ERP maps and ther efore, information processing; prestimulus microstate effects differed for different post-stimulus ERP microstates.