Suppression of the H reflex in humans by disynaptic autogenetic inhibitory pathways activated by the test volley
Suppression of the H reflex in humans by disynaptic autogenetic inhibitory pathways activated by the test volley
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测试齐射激活的突触自生抑制途径对人类 H 反射的抑制
DOI：
10.1113/jphysiol.2002.021683
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
E. Pierrot‐Deseilligny
中科院分区：
文献类型：
--
作者：
V. Marchand;G. Nicolas;D. Burke;E. Pierrot‐Deseilligny
目前的研究旨在通过在试验中强调I组传入事件的抑制作用来增加对H反射大小的现有限制。观察到，在股四头肌(Q)强烈自愿收缩期间，后期腓深肌（DP）对Q H反射的促进被抑制，但正在进行的肌电图的促进却没有。利用股中肌H反射或股外侧肌单运动单元（MUs）刺激后时间直方图（pths）中I组兴奋峰，对11例健康人进行股神经刺激后产生的Q运动神经元（MNs）兴奋，评价了调节刺激对股神经（FN）刺激产生的DP、腓浅神经（SP）和关节传入神经的影响。在DP和关节传入刺激后的强烈收缩以及DP和SP齐射时的休息时，观察到晚期H反射促进的抑制。在所有的单mu测试中，FN诱导的兴奋峰在强Q收缩时被DP刺激抑制，而在弱收缩时被联合调节齐射（SP与DP或关节）抑制。这些调节齐射本身即使在一起发射时也不会抑制背景MU放电。抑制不涉及峰的初始箱；它比可能的单突触Ia促进晚0.7 ms开始。我们认为这种抑制不是由于Ia末端的突触前抑制或复发性抑制，而可能反映了条件反射波和测试FN波中的I组传入事件在失突触非互反I组抑制的中间神经元上的收敛。由此可见，H反射的大小受到失突触抑制的限制，该抑制通路兴奋性的改变可引起H反射的显著变化。
The present studies were designed to increase an existing limitation on the size of the H reflex by accentuating an inhibitory effect of group I afferents in the test volley. They were precipitated by the observation that, during strong voluntary contractions of quadriceps (Q), the late deep peroneal (DP) facilitation of the Q H reflex was suppressed but the facilitation of the ongoing EMG was not. The effects of conditioning stimuli to DP, superficial peroneal (SP) and articular afferents on the excitation of Q motoneurones (MNs) produced by femoral nerve (FN) stimulation were assessed in 11 healthy human subjects using the H reflex of vastus intermedius or the peak of group I excitation in post‐stimulus time histograms (PSTHs) of single motor units (MUs) in vastus lateralis. The suppression of the late H reflex facilitation was observed during strong contractions after stimulation of DP and articular afferents, and at rest when DP and SP volleys were combined. In all single MUs tested, the FN‐induced peak of excitation was suppressed by DP stimulation during strong Q contractions and by a combination of conditioning volleys (SP with DP or articular) during weak contractions. By themselves these conditioning volleys did not inhibit the background MU discharge even when delivered together. The suppression did not involve the initial bins of the peak; it began 0.7 ms later than the probable onset of monosynaptic Ia facilitation. It is argued that the suppression is not due to presynaptic inhibition of Ia terminals or to recurrent inhibition, but probably reflects convergence between the conditioning volleys and group I afferents in the test FN volley onto interneurones of the disynaptic non‐reciprocal group I inhibition. It is concluded that the size of the H reflex is limited by disynaptic inhibition, and that changes in the excitability of this inhibitory pathway can produce prominent changes in the H reflex.