Hemispheric differences on auditory evoked response suppression in schizophrenia

USING binaural stimuli, schizophrenia subjects have worse auditory evoked r esponse (AER) suppression than normals in a paired-click paradigm. In this study we investigated hemispheric differences in AER suppression between gr oups using monaural and binaural stimulus presentation. Auditory evoked res ponses from 12 schizophrenia and 12 normal subjects were recorded with a 14 8-channel whole-head biomagnetometer. One hundred and twenty pairs of click s were presented in three counterbalanced blocks (left, right, binaural). W ith monaural stimuli, patients had worse M100 suppression than normals in i psilateral (effect size -2.13) but not in contralateral hemisphere (effect size -0.43). The groups did not differ on gamma band response suppression. Overall, the best group separations were obtained with binaural stimulus pr esentation on M100 suppression (effect size -4.14). (C) 1999 Lippincott Wil liams & Wilkins.