Excitability changes in primary motor cortex just prior to voluntary muscle relaxation
Excitability changes in primary motor cortex just prior to voluntary muscle relaxation
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在随意肌肉放松之前初级运动皮层的兴奋性变化
DOI：
10.1152/jn.00489.2014
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Higashi T
中科院分区：
文献类型：
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作者：
Suzuki T;Sugawara K;Takagi M;Higashi T
我们假设，初级运动皮层（M1）的活动并不只是在随意肌肉放松之前立即减少;相反，它是动态的，并作为一个活跃的皮层过程。因此，我们研究了肌肉放松过程中M1兴奋性变化的详细时间过程。10名健康的参与者进行了一项简单的反应时间任务。发出开始信号后，他们迅速终止右手食指等长外展，输出最大随意收缩力20%的恒定肌肉力，并进行随意肌肉放松。在发出启动信号之前和之后随机输送经颅磁刺激脉冲，并记录右侧第一骨间背肌的运动诱发电位（MEP）。我们选择的时间过程相对于一个适当的参考点，自愿放松的开始，检测兴奋性的变化M1。MEP振幅从80到60 ms之前估计的肌电图偏移量显着大于其他时间段。动态兴奋性的变化，在M1快速自愿肌肉放松之前，表明皮层控制肌肉放松是通过积极的处理，而不是简单的停止活动。根据这种动力学，需要重新考虑肌肉松弛的皮质机制。
We postulated that primary motor cortex (M1) activity does not just decrease immediately prior to voluntary muscle relaxation; rather, it is dynamic and acts as an active cortical process. Thus we investigated the detailed time course of M1 excitability changes during muscle relaxation. Ten healthy participants performed a simple reaction time task. After the go signal, they rapidly terminated isometric abduction of the right index finger from a constant muscle force output of 20% of their maximal voluntary contraction force and performed voluntary muscle relaxation. Transcranial magnetic stimulation pulses were randomly delivered before and after the go signal, and motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous muscle. We selected the time course relative to an appropriate reference point, the onset of voluntary relaxation, to detect excitability changes in M1. MEP amplitude from 80 to 60 ms before the estimated electromyographic offset was significantly greater than that in other intervals. Dynamic excitability changes in M1 just prior to quick voluntary muscle relaxation indicate that cortical control of muscle relaxation is established through active processing and not by simple cessation of activity. The cortical mechanisms underlying muscle relaxation need to be reconsidered in light of such dynamics.