Schizophrenia patients present aberrant brain activation patterns during verbal and spatial working memory tasks: an fMRI study

We aimed to identify the physiological correlates of maintenance-related WM deficits in schizophrenia by investigating schizophrenia patients with fMRI while they performed tasks specifically involving articulatory rehearsal, nonarticulatory phonological maintenance, and the maintenance of spatial information. 12 patients and 12 matched healthy subjects participated in the study. We applied two variants of a verbal and one variant of a spatial Sternberg-task. Patients performed significantly worse than controls in the phonological and the spatial WM-task. Further, the patients showed reduced brain activations in several areas within the circuits subserving the maintenance of phonological information (right frontal operculum, left intraparietal sulcus, right posterior cingulate cortex) or spatial material (bilateral superior parietal cortex, right inferior temporal cortex, right occipital cortex) in WM, suggesting that these networks are dysfunctional. At the same time, patients exhibited significantly stronger activation in other brain regions (e.g. right hippocampus, right frontal eye field and right inferior parietal cortex), which may be interpreted to reflect compensatory processing. These data provide evidence that the maintenance of verbal and spatial material is impaired in schizophrenia and that these deficits are associated with dysfunctions in the underlying brain networks.