14 Cerebral Potentials During Voluntary Ramp Movements in Aiming Tasks

Abstract

Publisher Summary In recent neurophysiological studies of motor performance, two classes of voluntary movements are often distinguished: a “ballistic” and “ramp” type of movement. Ballistic movements are brief (about 200 msec and less), fast, and thought to be “preprogramed,” that is launched without peripheral guidance. Ramp movements are slow, smooth, carried out in more than 500 msec, and are highly responsive to be controlled by peripheral sensory feedback. Scalp recorded cerebral potentials related to self-paced voluntary movements in man have been studied mainly in ballistic movements, especially in brisk isotonic or isometric contractions of limb muscles. The most obvious features of the potentials are a gradually increasing negative shift over both hemispheres beginning 1 sec or more prior to EMG onset, which subsides rapidly with a complex positive deflection after the initiation of movement. Subdural recordings have verified the cortical origin of these movement-related potentials in man.