Neurophysiological correlates of psychomotor activity in chronic schizophrenics.

The movement-related brain macropotentials (MRBMs) of 13 chronic schizophrenics (7 paranoid and 6 hebephrenic) were recorded during a motor perceptual task and compared to those of 13 normal subjects matched by age, sex and IQ. The cerebral activity was recorded from Fpz, Fz, Cz, Pz, and right and left precentral areas and the electromyographic activities from the left and right forearm flexor muscle groups. Analysis of variance was performed to test the correlation between the MRBMs and groups, sets and performances. The results indicate that the performance considered in tests of 'performance time,' as 'performance shift' and as number of 'target performances' was poorer in chronic schizophrenics than it was in the control group. In parallel with the performance, the MRBMs of chronic schizophrenics were also significantly different in comparison to the normal subjects. In particular, the BP amplitude was reduced in all areas; the MCP and P200 were also abnormally reduced. The SPP was present but it had a small amplitude in the parietal region. These differences in chronic schizophrenics could be explained as multidimensional biopsychological deficits: the disturbed performance is the result of impairment in developing appropriate changes of set, defective inhibition of sensory information, and reduced utilization of the outcome data.