Visual evoked potential (VEP) reducing: A vertex feature of late components

Visual evoked potential (VEP) augmenting-reducing (A/R) was studied in a healthy, male, right-handed sample of 16 Ss, 18-19 years in age. Occipital (Oz) P115-N147 (P1N1) and N147-P180 (N1P2) were compared with vertex (Cz) P98-N127 (P1N1) and N127-P178 (N1P2) components. Vertex reducers were occipital augmenters in the two components studied. No clear slope differences between Oz and Cz were seen in augmenters. Oz reduction appeared only for the more endogenous N1P2 component. Results are related to recording site (association vs primary cortex) and behavioral significance of VEP components. Active inhibitory nonsensory processes related to personality are seen in association cortex and late VEP components.