Large involuntary forces consistent with plateau-like behavior of human motoneurons
Large involuntary forces consistent with plateau-like behavior of human motoneurons
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DOI：
10.1523/jneurosci.21-11-04059.2001
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发表时间：
2001-06-01
影响因子：
5.3
通讯作者：
Gandevia, SC
中科院分区：
文献类型：
--
作者：
Collins, DF;Burke, D;Gandevia, SC
当电刺激作用于人体肌肉时，所引起的力通常被认为是外周性的。然而，在放松的人身上，刺激（1毫秒脉冲，100赫兹）对跖部和脚踝的肌肉产生的力比周围特性产生的力多5倍。这种额外的力叠加在运动轴突刺激的直接反应上，产生的力高达最大自主收缩时产生的力的40%，并且在刺激部位近端的胫神经麻醉时被消除。因此，它一定是由脊髓内运动神经元的激活引起的。附加力可以由低阈值传入信号的刺激引起，扭曲了力与刺激频率的经典关系，并且通常比刺激持续时间更长。刺激后，27个比目鱼肌运动单元的平均放电率为5.8 +/- 0.2 Hz。额外的力增量不能归因于自愿干预，因为它们存在于3名睡眠受试者和2名胸脊髓病变受试者中。这一现象与运动神经元内平台电位的激活是一致的，如果是这样的话，目前的发现意味着平台电位可以对人类神经系统产生的力做出很大的贡献。
When electrical stimulation is applied over human muscle, the evoked force is generally considered to be of peripheral origin. However, in relaxed humans, stimulation (1 msec pulses, 100 Hz) over the muscles that plantarflex the ankle produced more than five times more force than could be accounted for by peripheral properties. This additional force was superimposed on the direct response to motor axon stimulation, produced up to 40% of the force generated during a maximal voluntary contraction, and was abolished during anesthesia of the tibial nerve proximal to the stimulation site. It therefore must have resulted from the activation of motoneurons within the spinal cord. The additional force could be initiated by stimulation of low-threshold afferents, distorted the classical relationship between force and stimulus frequency, and often outlasted the stimulation. The mean firing rate of 27 soleus motor units recorded during the sustained involuntary activity after the stimulation was 5.8 +/- 0.2 Hz. The additional force increments were not attributable to voluntary intervention because they were present in three sleeping subjects and in two subjects with lesions of the thoracic spinal cord. The phenomenon is consistent with activation of plateau potentials within motoneurons and, if so, the present findings imply that plateau potentials can make a large contribution to forces produced by the human nervous system.