Neural Correlates of Verbal and Visuospatial Working Memory in Schizophrenic Patients as Revealed by fMRI

Abstract:
Abstract: Schizophrenic patients (n=16) and healthy controls (n=12) were studied with fMRI during performance of a 2-back task. The task was designed such that verbal as well as visuospatial working memory function could be studied using physically identical stimuli. The task was taken from a prior study of our group but adjusted in details in order to make it performable for partly remitted schizophrenic inpatients. Analysis was performed by means of SPM99b. In contrast to the majority of PET-studies and recent fMRI studies there were no major group differences for the main effects in the verbal as well the visuospatial domain, i.e. the typical working memory pattern (extended bifrontal and biparietal acitvations) was found in schizophrenic patients as well as in healthy controls. However, there were differences in the patterns of domain specific lateralization. These were complex and depended partly on task performance. We conclude that our task is able to elicit reliably neural activity during a working memory task in schizophrenic patients as measured by fMRI and that schizophrenic patients differ from healthy controls in the contribution of both hemispheres for domain specific working memory functions.