指神经刺激对人第一背侧骨间肌运动单位放电的影响。

The effects of digital nerve stimulation on the firing of motor units in human first dorsal interosseous muscle.

Datta A K, Stephens J A

J Physiol. 1981 Sep;318:501-10. doi: 10.1113/jphysiol.1981.sp013880.

Abstract

The effect of cutaneous stimulation on the firing of single motor units has been studied during voluntary contractions in human first dorsal interosseous muscle. 2. Electrical stimulation of the index finger at 3 x threshold for perception reduced the firing rate of most units recruited at voluntary contraction strengths less than 1.5 N and increased the firing rate of all units recruited at contraction strengths greater than 1.5 N. The firing rate of all slow twitch units (contraction time greater than 75 msec) was reduced. The behaviour of fast twitch units was mixed but at this stimulus strength all units recruited at contraction strengths greater than 1.5 N had their firing rate increased. 3. Tested at different stimulus strengths, the stronger the stimulus the more the firing rate of low threshold units was reduced. The firing rate of units recruited at high contraction strength was increased by weak stimuli but reduced by strong stimuli. 4. It is concluded that stimulation of the index finger shifts the weighting of synaptic input associated with a voluntary contraction to favour the activity of the more powerful fast twitch motor units in first dorsal interosseous muscle.

摘要

在人类第一背侧骨间肌的自主收缩过程中，研究了皮肤刺激对单个运动单位放电的影响。2. 以3倍感觉阈值对食指进行电刺激，在自主收缩强度小于1.5 N时，降低了大多数被募集运动单位的放电频率；在收缩强度大于1.5 N时，增加了所有被募集运动单位的放电频率。所有慢肌纤维运动单位（收缩时间大于75毫秒）的放电频率都降低了。快肌纤维运动单位的表现则各不相同，但在这种刺激强度下，所有在收缩强度大于1.5 N时被募集的运动单位，其放电频率都增加了。3. 在不同刺激强度下进行测试，刺激越强，低阈值运动单位的放电频率降低得越多。在高收缩强度下被募集的运动单位，其放电频率在弱刺激时增加，但在强刺激时降低。4. 得出的结论是，对食指的刺激改变了与自主收缩相关的突触输入权重，有利于第一背侧骨间肌中更强大的快肌纤维运动单位的活动。