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ISSN: 1935-1232 (P)

ISSN: 1941-2010 (E)

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Abstract

The Neuroanatomy of Verbal Working Memory in Schizophrenia: A Voxel-Based Morphometry Study

Author(s): Gianfranco Spalletta , Francesco Tomaiuolo , Margherita Di Paola ,Alberto Trequattrini , Pietro Bria , Emiliano Macaluso ,Richard S. J. Frackowiak , Carlo Caltagirone

Background: Abnormalities of language expression and verbal working memory impairment have been described in schizophrenic subjects. Purpose: To investigate the relationship between verbal working memory performance and cerebral structure in schizophrenic patients and control subjects. Method: Twenty-one Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition (DSM-IV) schizophrenic subjects and twenty-one control subjects underwent T1- weighted magnetic resonance imaging (MRI). Grey (GM) and white matter (WM) densities were evaluated using voxelbased morphometry (VBM). We administered the verbal n-back task to assess verbal working memory performance. Findings: A linear regression model, with illness duration included as a covariate, showed that WM density values in the pars opercularis of the left inferior frontal gyrus were positively and specifically correlated (t>7.16, DF=18, r=0.878, p<0.05 corrected for multiple comparisons, at voxel level) with verbal working memory performance in schizophrenic patients. The cluster showing this relationship between performance and WM density extended from the inferior frontal gyrus to the parietal operculum (p-corrected<0.05, at cluster level). Because of its shape and position, the cluster is most probably located in the third component of the superior longitudinal fasciculus. This finding was specific for WM and was not found in control subjects. Conclusions: The hypothesis that there is a direct and specific relationship between verbal working memory performance and the integrity of the WM in frontal language areas in schizophrenia is confirmed by the results of this study. Poor working memory is reflected in abnormal frontal WM in the dominant hemisphere and, hence, probably reflects a failure of intercortical connectivity