Brain Mechanisms in Voluntary Movement

Abstract

Thirty years ago, shortly following the Hixon Symposium on which the present meeting is patterned, Karl Lashley was kind enough to take me on as a postdoctoral fellow at the Yerkes Laboratories of Primate Biology in Orange Park, Florida. It therefore brings back many memories today as I speak on movement, for it was with movement that Lashley was concerned in his Hixon Symposium paper, “The Problem of Serial Order in Behavior.” Furthermore, it was in association with Lashley that my work on monkeys began—with studies on brain mechanisms underlying auditory-visual association. At the time of these early studies (Evarts, 1952), much of the work on the cerebral cortex in general and the motor cortex in particular utilized the technique of cerebral ablation and/or electrical stimulation, but in the intervening years a third technique has been developed, one that allows observations of neuronal activity in the brain of the intact animal, and it is with the use of this third technique that I am concerned in this discussion of brain mechanisms in voluntary movement. The pioneering work in this area was done by Herbert Jasper (1958), who studied activity of single brain cells in association with acquisition of conditioned responses. Jasper was interested in the events occurring in association with the learning process, but when I entered the field I devoted attention primarily to the somewhat simpler task of observing the neurophysiological correlates of well-established volitional movements.