COMMON DRIVE OF MOTOR UNITS IN REGULATION OF MUSCLE FORCE

The neuromuscular system is responsible for all our interactions with our environment. Although recent decades have witnessed numerous disco veries that have shed light into various properties of this system, th e basic principles underlying its overall operation still remain poorl y understood. In this article, Carlo J. De Luca and Zeynep Erim discus s the concept of common drive of motor units that Provides a possible scheme for the control of motor units, unifying various seemingly isol ated findings that have been reported. According to this concept, a po ol of motor units that makes up a muscle is controlled collectively du ring a contraction of that muscle. The unique firing patterns of indiv idual motor units are effected, not by separate command signals sent t o these units, but by one common drive to which motor units respond di fferently. The specific architecture of the system and the orderly gra dation in the inherent properties of individual elements enable a sing le source to control the activities of all the motor units in a given pool. Such an arrangement relieves the CNS from the burden of monitori ng and regulating each motor unit separately.