THE ROLE of the corticospinal tract in the initiation, maintenance, and control of voluntary movement has been much discussed in recent years. The fact that in man cerebral pedunculotomy, thought to interrupt the corticospinal fibers, was followed by an unpredictable alteration of muscular tone and power1,2 pointed up the dilemma which plagued clinical neurologists in their consideration of "the pyramidal syndrome." It therefore seems appropriate to present some experimental results of this procedure. From a larger series of pedunculotomized monkeys, the five animals which survived for more than eight months were selected for this study.
Methods
The left cerebral peduncle of five adult Macaca mulatta monkeys was sectioned by a subtemporal approach. The animals were anesthetized by sodium pentobarbital administered intravenously. A No. 7 rubber perforated stopper was placed between the teeth to open the mouth and depress the coronoid process of the mandible. The animals were placed