Leis A A, Stĕtkárová I, Berić A, Stokić D S
Department of Neurology, University of Mississippi Medical Center, Jackson 39216-4505, USA.
Muscle Nerve. 1995 Dec;18(12):1464-70. doi: 10.1002/mus.880181218.
The physiologic mechanisms generating the cutaneous silent period (CSP) remain uncertain. It is not known whether the CSP occurs because of inexcitability of the spinal motor neuron. We therefore, assessed excitability of the motor neuron during the CSP using F-wave responses. H-reflexes were also elicited during the CSP. Electrical stimulation to the fifth digit produced the CSP in the voluntarily contracting abductor pollicis brevis muscle (APB). Median nerve stimulation at the wrist elicited control F or H responses during isometric APB contraction (condition 1) and in resting muscle (condition 2). Control amplitudes were compared to those elicited in the midst of the CSP. In Condition 1, F-wave amplitudes and frequency during the CSP were unchanged compared with controls. However, F-waves were increased in amplitude and frequency during the CSP (P < 0.001) relative to responses elicited in resting muscle (condition 2). H-reflexes during the CSP were suppressed (P < 0.001) compared with controls elicited during contraction (condition 1), but facilitated relative to the resting state (condition 2) in which no H-reflexes were elicitable. We conclude that spinal motor neurons remain excitable to antidromic volleys at the same time that the corticospinal volley is inhibited to produce the CSP. Moreover, motor neuron excitability appears to be increased during the CSP compared to the relaxed state.
产生皮肤静息期（CSP）的生理机制尚不清楚。目前尚不清楚CSP的出现是否是由于脊髓运动神经元兴奋性降低所致。因此，我们使用F波反应评估了CSP期间运动神经元的兴奋性。在CSP期间也引出了H反射。对小指进行电刺激在拇短展肌（APB）自主收缩时产生了CSP。在等长APB收缩期间（条件1）和静息肌肉中（条件2），在腕部刺激正中神经引出对照F波或H反射。将对照波幅与CSP期间引出的波幅进行比较。在条件1中，CSP期间的F波幅和频率与对照相比没有变化。然而，相对于在静息肌肉中引出的反应（条件2），CSP期间F波的波幅和频率增加（P<0.001）。与收缩期间引出的对照（条件1）相比，CSP期间的H反射受到抑制（P<0.001），但相对于静息状态（条件2）（此时无法引出H反射）则表现为易化。我们得出结论，在皮质脊髓冲动被抑制以产生CSP的同时脊髓运动神经元对逆行冲动仍保持兴奋性。此外，与松弛状态相比，CSP期间运动神经元的兴奋性似乎增加。
