Cortical mechanisms of unilateral voluntary motor inhibition in humans
Cortical mechanisms of unilateral voluntary motor inhibition in humans
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DOI：
10.1016/j.neures.2005.09.002
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发表时间：
2005-12-01
影响因子：
2.9
通讯作者：
Shibasaki, H
中科院分区：
文献类型：
--
作者：
Begum, T;Mima, T;Shibasaki, H
虽然运动控制往往是一个目标导向的事件，很少有人知道的机制终止运动性能。为了研究什么类型的皮层激活的肌肉放松需要终止的行为，我们进行了单脉冲和双脉冲经颅磁刺激（TMS）的研究，在自愿肌肉放松9名正常志愿者。受试者保持右侧第一背侧骨间肌（FDI）的弱等长收缩，并根据视觉提示增加收缩水平（收缩）、终止收缩（松弛）或保持收缩（不动）。运动诱发电位（MEP）和沉默期（SP）记录从FDI在运动活动。为了测量皮层内抑制（ICI），我们还进行了双脉冲TMS，以2 ms的刺激间隔施加阈下条件刺激。当单脉冲TMS在肌肉放松前（-21至-70 ms）给予时，MEP降低，而SP不变。皮质内抑制较小的肌肉松弛之前。单侧随意性肌肉松弛可能与皮质内抑制系统的激活无关，而是与皮质脊髓系统的可能兴奋有关，皮质脊髓系统可以抑制运动神经元的双突触。这些发现表明，多种抑制机制以不同的方式实现运动抑制。(c)2005年Elsevier爱尔兰有限公司和日本神经科学学会。All rights reserved.
While motor control is very often a goal-oriented event, little is known about the mechanisms underlying the termination of motor performance. To investigate what type of cortical activation underlies the muscle relaxation required to terminate the act, we performed single- and double-pulse transcranial magnetic stimulation (TMS) studies during voluntary muscle relaxation in nine normal volunteers. Subjects maintained a weak isometric contraction of the right first dorsal interosseous muscle (FDI), and either increased the level of contraction (Contraction), terminated the contraction (Relaxation), or maintained it (No-go) depending on a visual cue. Motor evoked potentials (MEP) and the silent period (SP) were recorded from the FDI during motor activity. To measure intra-cortical inhibition (ICI), we also performed double-pulse TMS, applying subthreshold conditioning stimuli at interstimulus intervals of 2 ms. When single-pulse TMS was given just prior to muscle relaxation (-21 to -70 ms), the MEP was reduced while the SP was unchanged. Intra-cortical inhibition was smaller just prior to the muscle relaxation. Unilateral voluntary muscle relaxation may not be associated with activation of the intracortical inhibitory system, but rather with the possible excitation of the corticospinal system, which can inhibit motoneurons disynaptically. These findings suggest that multiple inhibitory mechanisms act in diverse ways to achieve motor inhibition. (c) 2005 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.