Schieppati M, Poloni M, Nardone A
Neurosci Lett. 1985 Oct 24;61(1-2):177-81. doi: 10.1016/0304-3940(85)90421-5.
Changes in excitability of the soleus (Sol) monosynaptic reflex arc were investigated in spastic subjects, affected by amyotrophic lateral sclerosis (ALS), upon voluntary relaxation of tonic contraction of triceps surae muscle. Force and electromyograms (EMG) were recorded during triceps release, performed in response to an acoustic signal, in a reaction-time (RT) situation. Sol H-reflex was evoked at random during the task, and its amplitude was referred in time to the end of Sol EMG. At variance with the results for the same task in normal subjects, it was found that in ALS patients the RTs of the termination of EMG were longer than those of the beginning of the EMG, the decrease in force was prolonged and perturbed owing to intercurrent clonus-like EMG activity, and the H-reflex did not undergo the expected profound inhibition. It is suggested that the absence of the activation of presynaptic inhibitory mechanisms by the descending command to release brings about major disorders in voluntary muscle relaxation.
在患有肌萎缩侧索硬化症（ALS）的痉挛性受试者中，研究了比目鱼肌（Sol）单突触反射弧兴奋性的变化，这些受试者在腓肠肌三头肌强直性收缩的自主放松过程中受到影响。在反应时间（RT）情况下，响应声音信号进行三头肌放松时记录力量和肌电图（EMG）。在任务期间随机诱发Sol H反射，并将其幅度及时参考到Sol EMG结束时。与正常受试者在相同任务中的结果不同，发现在ALS患者中，EMG终止的反应时间比EMG开始的反应时间长，由于间歇性阵挛样EMG活动，力量下降延长且受到干扰，并且H反射没有受到预期的深度抑制。有人认为，下行释放指令未能激活突触前抑制机制会导致自主肌肉放松出现重大障碍。
