Monosynaptic facilitation of flexor digitorum superficialis motoneurons mediated by Group Ia afferents from the extensor carpi radialis in humans
Monosynaptic facilitation of flexor digitorum superficialis motoneurons mediated by Group Ia afferents from the extensor carpi radialis in humans
复制标题
人类桡侧腕伸肌 Ia 组传入神经介导的指浅屈肌运动神经元的单突触促进
DOI：
10.1111/ejn.15784
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发表时间：
2022
影响因子：
3.4
通讯作者：
Naito Akira
中科院分区：
文献类型：
--
作者：
Nito Mitsuhiro;Yoshimoto Takuya;Hashizume Wataru;Sato Tomomi;Shimada Kazuto;Shindo Masaomi;Naito Akira
众所周知，手腕的位置会影响握力。我们专注于支持运动的脊髓反射弧，并使用刺激后时间直方图（PSTH）和肌电图平均（EMG-A）方法研究了桡侧腕伸肌（ECR）的低阈值传入对指浅屈肌（FDS）运动神经元兴奋性的影响。对支配ECR的桡神经分支施加强度低于运动阈值的电条件刺激。在PSTH研究中，在7名受试者中研究了电条件刺激后单个运动单位的放电概率的变化。记录了36/60个FDS运动单位的早期显著峰值（击发概率增加：易化）。其余24个运动单位没有表现出任何影响。ECR肌腹的弱机械条件刺激诱导了类似的峰。易化的中枢潜伏期与同侧单突触易化的中枢潜伏期相当。在EMG‐A研究中，检查了12名受试者由条件刺激诱导的FDS的校正和平均肌电图的变化。一个早期和显着的峰值（促进）诱导的电和机械条件刺激。对ECR肌腹撤去振动后，这种易化作用减弱。在PSTH和EMG‐A研究中，皮肤神经刺激从未诱导过易化。这些结果表明，Ia组传入的ECR增加FDS运动神经元的兴奋性，通过在脊髓中的单突触路径。这些反射弧可能促进手抓握运动。
Wrist position is known to affect the grip strength. We focused on the spinal reflex arc, which would support the movement, and investigated the effects of low‐threshold afferents from the extensor carpi radialis (ECR) on the excitability of the flexor digitorum superficialis (FDS) motoneurons using the post‐stimulus time‐histogram (PSTH) and electromyogram‐averaging (EMG‐A) methods. Electrical conditioning stimulation of an intensity below the motor threshold was applied to the radial nerve branch innervating the ECR. In the PSTH study, changes in the firing probability of single motor units after electrical conditioning stimulation were investigated in seven subjects. An early and significant peak (increase in the firing probability: facilitation) was recorded for 36/60 FDS motor units. The remaining 24 motor units did not show any effects. Weak mechanical conditioning stimulation of the ECR muscle belly induced a similar peak. The central latency of the facilitation was equivalent to that of the homonymous monosynaptic facilitation. In the EMG‐A study, changes in the rectified and averaged electromyograms of FDS induced by conditioning stimulation were examined in 12 subjects. An early and significant peak (facilitation) was induced by both electrical and mechanical conditioning stimulations. The facilitation decreased after withdrawal of the vibration to the ECR muscle belly. The facilitation was never induced by cutaneous nerve stimulation in the PSTH and EMG‐A studies. These findings suggest that Group Ia afferents from the ECR increase the excitability of FDS motoneurons through a monosynaptic path in the spinal cord. These reflex arcs likely facilitate hand grasping movements.