Neurophysiology of reaching

Reaching serves to position the hand at desired points in immediate extrapersonal space. It is accomplished by well-coordinated and tightly coupled motions at the shoulder and elbow joints (Soechting & Lacquaniti, 1981), and is usually directed to visual targets. During reaching, the hand is preshaped according to the characteristics of the object that is to be manipulated (Jeannerod & Biguer, 1982). Thus, behaviorally, reaching is a complex act that involves sensory-motor integration and the concurrent preparation for handling the object of interest. I discuss in this chapter the neurophysiological studies that pertain to reaching itself. Other reviews have dealt with general aspects of reaching (Georgopoulos, 1986), the anatomical pathways involved in reaching (Humphrey, 1979), the effects of reaching of brain lesions (Jeannerod, 1986), and the visuomotor coordination underlying reaching to visual targets (Georgopoulos, 1989).