The N2 component of the event-related potential in schizophrenic patients.

Event-related potentials (ERPs) to easy and difficult infrequent visual target stimuli were recorded in unmedicated schizophrenic patients and age-matched controls. N2 difference wave forms were computed by subtracting the ERP to a frequent non-target stimulus from the ERP to each target. The N2 component was identified in these difference wave forms. All subjects showed longer latency N2 and P3 peaks to the difficult target than to the easy target. Schizophrenic patients had longer latency N2 peaks than controls to both targets. Schizophrenic patients also showed reduced P3 amplitudes to both targets compared to controls. The prolonged N2 latency in schizophrenics accounts for a substantial portion of the delayed reaction time commonly observed in this group. N2 latency prolongation appears to be yet another evoked potential abnormality in schizophrenic patients.