Ziemann U, Netz J, Szelényi A, Hömberg V
Neurological Therapy Centre, Heinrich Heine University of Düsseldorf, FRG.
Neurosci Lett. 1993 Jun 25;156(1-2):167-71. doi: 10.1016/0304-3940(93)90464-v.
In the voluntarily activated muscle, transcranial magnetic stimulation (TMS) of motor cortex produces subsequently to the motor evoked potential (MEP) a silent period (SP) in the electromyogram. We studied the time course of soleus motoneuron (MN) pool excitability after conditioning TMS by Hoffmann reflex (HR) testing, to determine whether inaccessibility of MNs after corticospinal input contributes to the SP. Coincidently with the early part of the SP, and only in the contracting soleus, MN depression was obtained that covaried with the degree of preinnervation, and with the size of the preceding MN discharge. However, MN excitability recovered significantly prior to the end of the SP. It is concluded that in the contracting soleus spinal mechanisms (most likely Renshaw inhibition and MN afterhyperpolarization) contribute to the early part of the SP, while the late part of the SP is supraspinal (probably cortical) in origin.
在自主激活的肌肉中，经颅磁刺激（TMS）作用于运动皮层后，在肌电图中运动诱发电位（MEP）之后会产生一个静息期（SP）。我们通过霍夫曼反射（HR）测试研究了条件性TMS后比目鱼肌运动神经元（MN）池兴奋性的时间进程，以确定皮质脊髓输入后MN难以接近是否导致了SP。与SP的早期部分同时出现，且仅在收缩的比目鱼肌中，观察到MN抑制，其与预激活程度以及先前MN放电的大小呈共变关系。然而，MN兴奋性在SP结束前显著恢复。结论是，在收缩的比目鱼肌中，脊髓机制（很可能是闰绍抑制和MN超极化后电位）导致了SP的早期部分，而SP的晚期部分起源于脊髓以上（可能是皮质）。
