Altered endogenous negativities of the visual event-related potential in remitted schizophrenia

Visual event-related potentials (ERPs) were recorded during a simple response task (SRT) and a discriminative response task (DRT) in remitted schizophrenic outpatients and age-matched controls to examine 2 endogenous negative potentials: NA and N2c. The NA potentials were derived by subtracting the ERPs for SRT from those for non-target stimuli in DRT. Other subtracting wave forms, N2c potentials, were calculated as the difference between ERPs for target and non-target stimuli in DRT. Schizophrenics showed retardation in NA and N2c peaks and degradation in N2c amplitude relative to controls. The NA peak latency increased as much as the latencies of N2c and reaction time for DRT in schizophrenia. The NA peak emerged prior to the N2c peak, while the NA peak latency correlated closely with the N2c latency. These results indicate that the retarded NA peak latency may serve as a physiological marker for neurobiological vulnerability of schizophrenia.