The Japanese journal of neuropsychology

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ArticleTitle	Social cognitive impairments and structural/functional brain abnormalities in schizophrenia
Language	J
AuthorList	Kazuyuki Hirao, Chihiro Namiki, Makiko Yamada, Jun Miyata, Toshiya Murai
Affiliation	Department of Neuropsychiatry, Graduate School of Medicine, Kyoto University
Publication	Japanese Journal of Neuropsychology: 23 (4), 268-278, 2007
Received
Accepted
Abstract	Introduction: Social cognitive impairments in patients with schizophrenia affect their interpersonal relationships, which leads to difficulties in their social life. Meanwhile, recent neuroimaging studies have demonstrated regional brain structural/functional abnormalities in schizophrenia. However, the relationships between impaired social cognition and brain abnormalities in schizophrenia remain unclear. In this article, we focused on the two key components of social cognition, facial emotion recognition and "theory of mind (ToM)", and reviewed the impairments and its neural basis in schizophrenia as shown in our recent studies. Method: In our studies, twenty patients with schizophrenia and 20 group-matched healthy comparison participants underwent high-resolution magnetic resonance imaging (MRI) and were examined for social cognitive abilities based on facial emotion recognition and ToM tasks. Voxel-based morphometry (VBM) was applied to investigate regional brain structural alterations and manual tracing volumetry was also applied to small structures of the medial temporal lobe such as amygdala. Results: As for structural brain alterations, patients with schizophrenia exhibited gray matter reductions in the medial prefrontal cortex (MPFC), ventrolateral prefrontal cortex, left superior temporal gyrus, right insula, and amygdala. With regard to social cognitive abilities, the patients showed emotion-specific (sadness, surprise, disgust, and anger) impairments on the facial emotion recognition task and performed poorly on the ToM task which requires the ability to infer the emotion of others in social situations. Importantly, correlation analyses demonstrated the associations between poor performance on facial emotion recognition task and gray matter reduction in the amygdala of the patient group. Moreover, impaired ToM ability was associated with the MPFC reduction in the patients. Conclusions: Previous schizophrenia studies have investigated the relationships between impaired neurocognitive abilities (e. g., attention, working memory, and executive function) and frontal lobe dysfunction, especially in the dorsolateral prefrontal cortex. Recently, the study of social cognition in schizophrenia has received growing attention from the perspective of social neuroscience, and explored the relationships between impaired social cognitive abilities and brain abnormalities in the medial temporal structures or medial prefrontal cortex. Our findings suggest that in schizophrenia, structural abnormalities in the amygdala and MPFC make different contributions to impaired facial emotion recognition and ToM in social situations, respectively. These studies might help to better elucidate the underlying frontotemporal mechanisms for social cognitive impairments in schizophrenia as well as develop individualized treatment and rehabilitation for individuals with schizophrenia tailored to their specific impairments.
Keywords	schizophrenia, social cognition, theory of mind: ToM, medial prefrontal cortex: MPFC, amygdala