Warner J E, Wiegner A W
Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Exp Physiol. 1990 Mar;75(2):223-30. doi: 10.1113/expphysiol.1990.sp003396.
The increase with time of the stiffness of resting muscle and its effect on afferent nerve activity arising within the muscle were investigated in the leg of the anaesthetized rat. Nerve activity was recorded from the branch of the tibial nerve innervating the gastrocnemius muscle. A sinusoidal torque from a motor coaxial with the ankle produced small (less than 0.25 deg) oscillations of the resting foot that were interrupted by several cycles of a much larger amplitude displacement. After the perturbation, the same small torque caused larger (greater than 0.40 deg) oscillations, demonstrating a reduction in the resting or short-range stiffness of muscles acting at the joint. Turning off the torque for 30 s allowed the stiffness to return to its enhanced level. Afferent nerve activity in response to the small torque was greater following the perturbation, reflecting the larger oscillations. We conclude that thixotropic stiffening of muscles at rest reduces postural displacements produced by small torques as well as the quantity of afferent signals converging on the central nervous system from these events.
在麻醉大鼠的腿部，研究了静息肌肉硬度随时间的增加及其对肌肉内传入神经活动的影响。从支配腓肠肌的胫神经分支记录神经活动。与踝关节同轴的电机产生的正弦扭矩使静息足部产生小幅度（小于0.25度）的振荡，该振荡被几个更大幅度位移的周期打断。扰动后，相同的小扭矩会引起更大幅度（大于0.40度）的振荡，表明作用于关节的肌肉静息或短程硬度降低。关闭扭矩30秒可使硬度恢复到增强水平。扰动后，对小扭矩做出反应的传入神经活动增强，反映出振荡幅度更大。我们得出结论，静息肌肉的触变硬化减少了小扭矩产生的姿势位移以及这些事件中汇聚到中枢神经系统的传入信号数量。
