SLOW CORTICAL POTENTIAL SHIFTS MODULATE P300 AMPLITUDE AND TOPOGRAPHYIN HUMANS

Effects of the spontaneous slow cortical potential (SCP) shifts of the electroencephalogram (EEG) on the P300 response were investigated on ten healthy volunteers. P300 responses were recorded using an auditory oddball paradigm, where target stimuli were presented regularly after every four standard stimuli. Single event-related potential (ERP) swe eps exhibiting negative or positive SCP shifts were averaged separatel y. The P300 amplitude was significantly larger during negative SCP shi fts. Furthermore, the topographies of P200 and P300 waves obtained dur ing negative and positive SCP shifts showed significant differences. T he results indicate that the SCP shifts in single ERP sweeps, which ar e considered to be correlated with the arousal or basic activity level of the cortex, explain at least part of the inter-trial variability o f P300 response. (C) 1998 Elsevier Science ireland Ltd. All rights res erved.