Schizophrenia Research, 24(1,2):231-232, 1997.

Brain event-related potentials in schizophrenia during a visuospatial task

G. Bruder, J. Kayser, C. Tenke, M. Friedman, E. Rabinowicz, X. Amador, J. Gorman

Department of Biopsychology, New York State Psychiatric Institute, New York, NY 10032, USA
 

Abstract

Event-related brain potentials (ERPs) were used to study electrophysiologic correlates of visuospatial processing in schizophrenia. The purpose was to determine whether abnormalities of visual information processing in schizophrenia are related to early sensory-attentional processing, reflected in the N1 or N2 brain potentials, or to a later stage of cognitive processing, reflected in the P3 potential. ERPs were recorded from 30 electrode sites while subjects were engaged in a dot enumeration task, in which 2-6 dots were presented to the left or right visual field (180 ms duration). Twenty-five patients from the Schizophrenia Research Unit with a DSM-IV consensus diagnosis of schizophrenia (n=17) or schizoaffective (n=8) and 25 normal controls were tested. Patients showed poorer accuracy when compared to controls (p< .001) and both groups showed the expected left visual field (right hemisphere) advantage for this visuospatial task (p<.001). Patients had markedly smaller N1 and N2 amplitude when compared to normal controls (each p<.005), but did not differ from normal controls in P3 amplitude, which agrees with prior findings for visual ERPs. Normal controls showed greater N1 amplitude at parietal sites contralateral to the visual field of dot stimuli, whereas patients did not (p<.005). Among patients, greater P3 amplitude was associated with better accuracy of dot numeration (r=0.63 - 0.68, p<.001, at Cz and Pz). These findings point to a abnormality of early sensory-attentional processing in schizophrenia, which appears to involve a basic deficit in orienting of attention to the stimulus hemifield.