Tsukahara R, Aoki H, Yabe K, Mano T
Institute for Developmental Research, Aichi Human Service Center, Japan.
Electroencephalogr Clin Neurophysiol. 1995 Oct;97(5):223-30. doi: 10.1016/0013-4694(94)00327-h.
We compared the single motor unit (SMU) activity between movements with a premotion silent period (PMSP) and without PMSP in EMG. Fourteen SMUs in the gastrocnemius muscle and 6 SMUs in the soleus muscle were recorded from 5 volunteers during isometric plantar flexion. Tonically firing SMUs failed to fire just before the onset of a rapid contraction with PMSP more frequently than without PMSP. SMUs tended to fire within 10 msec (the gastrocnemius SMUs) or 20 msec (the soleus SMUs) from the onset of the phasic EMG discharge when PMSP occurred. In a rapid contraction without PMSP, the initial firing of SMUs occurred with longer latency than that in a rapid contraction with PMSP. The latency of the initial SMU firing in a rapid contraction related to the preceding time of the last SMU firing during a sustained contraction to the onset of the phasic EMG discharge. When the preceding firing was long enough, the latency distributed around 10 msec. On the other hand, for shorter preceding times, the latency lengthened with shortening of the preceding time. It is suggested that the PMSP makes the preceding time long and increases the susceptibility of motor units to the descending command at the initiation of a rapid contraction.
我们比较了肌电图中有无运动前静息期（PMSP）的运动之间的单运动单位（SMU）活动。在5名志愿者进行等长跖屈时，记录了腓肠肌中的14个SMU和比目鱼肌中的6个SMU。与无PMSP的情况相比，在有PMSP的快速收缩开始前，持续放电的SMU更频繁地停止放电。当出现PMSP时，SMU倾向于在相位性肌电图放电开始后的10毫秒内（腓肠肌SMU）或20毫秒内（比目鱼肌SMU）放电。在无PMSP的快速收缩中，SMU的初始放电潜伏期比有PMSP的快速收缩更长。快速收缩中初始SMU放电的潜伏期与持续收缩至相位性肌电图放电开始期间最后一个SMU放电的先前时间有关。当前续放电时间足够长时，潜伏期分布在10毫秒左右。另一方面，对于较短的续前时间，潜伏期会随着续前时间的缩短而延长。提示PMSP使续前时间延长，并增加了运动单位在快速收缩开始时对下行指令的敏感性。
