Movement-related cerebral potentials in schizophrenics.

Measures concerning the P2 component of movement-related cerebral potentials (MPs) (the time from the trigger produced by key-tapping to the onset of P2: T-N latency, the width of P2: N-P interval, and the amplitude of P2: N-P amplitude) and various clinical factors of 36 schizophrenics were studied and statistically compared with those of 35 normal subjects. Concerning the P2 component, 22/36 of the schizophrenics showed abnormal findings. These three measures, especially the N-P interval, are significantly related to various clinical symptoms at the stage when the MPs were recorded but are not related to the previous worst stage. The chronicity of schizophrenic illness influenced each measure of the T-N latency and N-P interval, both of which were significantly longer than those of the normal subjects. The pressure strength, the velocity of key-tapping, the duration of muscular contraction, (namely the manner of key-tapping) and the daily dosage of neuroleptics did not affect the P2 component. These results suggest that 1) the P2 component of MPs is related to certain brain functions as a signal of information processing concerning action and not to the peripheral feed-back mechanism and 2) abnormal waveforms of the MPs found in pathological psychiatric conditions of schizophrenia may be a reflection of disturbances of the central mechanism concerning action, attention and volition.