Abnormalities of motor imagery ability associated with spatial working memory dysfunction in chronic schizophrenic patients

Abstract

Background: Spatial working memory (SWM) and mental imagery involve the processes of encoding, maintaining, and transforming spatial information. Patients with schizophrenia show impairments in both SWM and mental imagery. Yet, there is scarce evidence on the relationship between impairment in the two cognitive functions in the patients. Objectives: The goal of the present study was to investigate motor imagery ability and SWM function and their relationship in schizophrenic patients. Methods: The present case-control study compared the performance of 18 schizophrenic patients and 18 normal persons. The motor imagery was evaluated with the mental hand rotation task (HRT) and SWM was examined with the Dot test of visuospatial working memory (VSWM) across the three delays. Results: The comparison of HRT results between the patients and the controls showed a slower and less accurate performance of the patients. On the Dot test of VSWM, performance was significantly less accurate at the three delays in schizophrenic patients relative to the controls. Moreover, there was a negative significant correlation between mental rotation accuracy and distance inaccuracy across the three delays in schizophrenic patients. Conclusions: These results provide further evidence that impaired passive maintenance of internal representation might be the underlying mechanism of motor imagery dysfunction in patients with schizophrenia.