Cerebrovascular accident alters P300 event-related potential characteristics

P300 event-related potentials to counted (target) and uncounted (background) visual stimuli were recorded from subjects who had sustained either a right or a left middle cerebral artery cerebrovascular accident (CVA) and from appropriate normal control subjects. Subjects were asked to count target stimuli and to ignore non-target stimuli. Standard measurements of the amplitude and latency of P300 components as well as intercorrelations among P300 wave forms from 3 brain regions (Fz, Cz, Pz) were collected. Amplitudes of N1-P2 and N2-P3 components as well as overall amplitude of the ERP wave form were reliably reduced by a CVA, but component latencies were not significantly affected. The amplitude reduction associated with a CVA cannot be simply interpreted as evidence for reduced cognitive efficiency because overall amplitudes and intercorrelations between brain regions of CVA patients were reduced for both counted and uncounted stimuli. The intercorrelations between brain regions were particularly reduced if the CVA was localized in the right hemisphere. For CVA patients, reduced component amplitudes may reflect decreased cortical intercommunication associated with damage to subcortical brain structures.