Possible mechanisms of delay in initiation of voluntary movements.

Studies were made of psychomotor responses and accompanying cortical evoked potentials in healthy subjects and patients with Parkinson's disease. Measurements showed that delays in a variety of psychomotor responses resulted from delays in movement initiation. The frontal regions showed increases in the N2 component of evoked potentials and delayed development of P3 waves. It is suggested that delayed initiation of movements in patients with Parkinson's disease might be associated with strengthening of frontal inhibitory systems, preventing the onset of movements.