Elsevier, Psychiatry Research: Neuroimaging, 3(211), p. 226-233, 2013
DOI: 10.1016/j.pscychresns.2012.09.001
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Anomalous activations of the prefrontal cortex (PFC) and posterior cerebral areas have been reported in previous studies of working memory in schizophrenia. Several interpretations have been reported: e.g., neural inefficiency, the use of different strategies and differences in the functional organization of the cerebral cortex. To better understand these abnormal activations, we investigated the cerebral bases of a working memory component process, namely refreshing (i.e., thinking briefly of a just-activated representation). Fifteen patients with schizophrenia and 15 control subjects participated in this fMRI study. Participants were told that whenever they saw a word on the screen, they had to read it silently to themselves (read and repeat conditions), and when they saw a dot, they had to think of the just-previous word (refresh condition). The refresh condition (in comparison with the read condition) was associated with increased activation in the left inferior frontal gyrus (T=3.55, p=0.009) and decreased connectivity within the prefrontal cortex and between the prefrontal and parietal cortices (T(s)>4.09, p(s)<0.05) in patients with schizophrenia in comparison with control subjects. These results suggest that prefrontal dysfunctions in schizophrenia might be related to a defective ability to initiate (rather than to execute) specific cognitive processes.