Motor dysfunction and sensorimotor cortex activation changes in schizophrenia: A study with functional magnetic resonance imaging

Recent studies demonstrate a diminished activation of the sensorimotor cort ex and supplementary motor area (SMA) in schizophrenia which may be involve d in the pathogenesis of neurological soft signs (NSS). Yet, the question w hether a retarded motor performance may account for these changes remained to be clarified. Twelve DSM-III-R schizophrenics and 12 healthy controls we re included. All subjects were right-handed. Nine patients received clozapi ne, two conventional neuroleptics, and one was drug-free. Functional magnet ic resonance imaging (fMRI) was obtained in a resting condition and during pronation/supination at three speed levels (low, medium, and high) with mot or performance recorded simultaneously using a pronation/supination device. While measures of motor retardation (i.e., repetition rate and amplitude o f the movements) did not differ between patients and controls, the variabil ity of performance was significantly (P < 0.05) increased in the patients' group. In addition, patients with schizophrenia showed a significantly (P < 0.05) decreased activation of the sensorimotor cortices. Similar, although nonsignificant (P = 0.09) activation changes were observed in the SMA. Act ivation differences were more pronounced at a slow speed and in the drug-fr ee patient. These results confirm a diminished sensorimotor cortex and SMA activation and indicate that variability of performance rather than retarde d performance per se may correspond to these changes. (C) 1999 Academic Pre ss.