Reduced event-related current density in the anterior cingulate cortex in schizophrenia

There is good evidence from neuroanatomic postmortem and functional imaging studies that dysfunction of the anterior cingulate cortex plays a prominen t role in the pathophysiology of schizophrenia. So far, no electrophysiolog ical localization study has been performed to investigate this deficit. We investigated 18 drug-free schizophrenic patients and 25 normal subjects wit h an auditory choice reaction task and measured event-related activity with 19 electrodes. Estimation of the current source density distribution in Ta lairach space was performed with low-resolution electromagnetic tomography (LORETA). In normals, we could differentiate between an early event-related potential peak of the N1 (90-100 ms) and a later N1 peak (120-130 ms). Sub sequent current-density LORETA analysis in Talairach space showed increased activity in the auditory cortex area during the first N1 peak and increase d activity in the anterior cingulate gyrus during the second N1 peak. No ac tivation difference was observed in the auditory cortex between normals and patients with schizophrenia. However, schizophrenics showed significantly less anterior cingulate gyrus activation and slowed reaction times. Our res ults confirm previous findings of an electrical source in the anterior cing ulate and an anterior cingulate dysfunction in schizophrenics. Our data als o suggest that anterior cingulate function in schizophrenics is disturbed a t a relatively early time point in the information-processing stream (100-1 40 ms poststimulus). (C) 2001 Academic Press.