BRAIN MECHANISMS IN MOTOR CONTROL

Abstract

Publisher Summary This chapter describes the brain mechanisms in motor control. In primates, a zone of cerebral cortex lying anterior to the central fissure contains a set of neurons whose axons pass without interruption to the spinal cord through a nerve bundle named the pyramidal tract and the neurons of this tract are called pyramidal tract neurons (PTNs). In the spinal cord, the axon terminals of PTNs end both in the interneuronal pool and on alpha and gamma motoneurons. Studies of PTN discharge in monkeys that are able to carry out differing movements depending upon the instructions they have received have revealed that one factor influencing motor cortex PTN discharge frequency in the absence of overt muscular contraction is the intention to move. The variation in PTN activity in relation to intention to move is seen even before any muscular activity occurs. It is found that when a monkey has learned that a particular signal means he should flex his elbow; PTNs adopt a pattern of discharge corresponding to the intention to flex. A different pattern of PTN discharge frequency is adopted if the monkey receives a signal instructing him to extend.