Granit R
Brain. 1975 Dec;98(4):531-56. doi: 10.1093/brain/98.4.531.
A review is given of recent work on the functional role of muscle spindles in the control of movement. The fusimotor neurons (gamma motoneurons) maintain the spindles in a state of responsiveness to length and to rate of change of length of muscle. Centrifugal control of muscle spindles takes two forms: first, a steady or slowly fluctuating tonic firing of fusimotor neurons, as a part of general states of arousal or readiness-to-move, independent of the firing of skeletomotor neurons (alpha motoneurons), and not related in time to specific movements; secondly, a precise coactivation of skeletomotor and fusimotor neurons (alpha-gamma linkage) which is related to the time-course of specific movements. Both types are likely to be important in man. Recent work on the connexions at the segmental level between spindle inputs, descending pathways, interneurons, gamma motoneurons and alpha motoneurons is reviewed and discussed, with special attention to work on man. These segmental circuits, rather than their individual components, are the units which are operated by reflexes and by central programmes for movemenst.
本文综述了有关肌梭在运动控制中功能作用的近期研究工作。梭内运动神经元（γ运动神经元）使肌梭保持对肌肉长度及长度变化速率的敏感状态。对肌梭的离心控制有两种形式：其一，作为觉醒或运动准备的一般状态的一部分，梭内运动神经元持续或缓慢波动的紧张性放电，独立于骨骼肌运动神经元（α运动神经元）的放电，且与特定运动在时间上无关；其二，骨骼肌运动神经元与梭内运动神经元精确的共同激活（α-γ关联），这与特定运动的时间进程相关。这两种类型在人类中可能都很重要。本文回顾并讨论了近期关于肌梭传入、下行通路、中间神经元、γ运动神经元和α运动神经元在节段水平上的联系的研究工作，特别关注了对人类的研究。这些节段性回路，而非其单个组成部分，是通过反射和运动的中枢程序来运作的单位。
