Sensitivity of H-reflexes and stretch reflexes to presynaptic inhibition in humans
Sensitivity of H-reflexes and stretch reflexes to presynaptic inhibition in humans
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DOI：
10.1152/jn.1998.80.2.610
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发表时间：
1998-08-01
影响因子：
2.5
通讯作者：
Nielsen, J
中科院分区：
文献类型：
--
作者：
Morita, H;Petersen, N;Nielsen, J
比较了17名健康人的比目鱼肌h反射、t反射和短潜伏期拉伸反射（M1）对股二头肌肌腱弱拍或腓总神经刺激引起的突触前抑制的敏感性。股二头肌肌腱拍打可使h反射强烈抑制长达300-400 ms（在70 ms的调节测试间隔中，对照的h反射抑制为48 +/- 23%，平均+/- SD）。相反，由踝关节快速被动背屈引起的短潜伏期比目鱼肌拉伸反射不受抑制。跟腱轻拍引起的比目鱼t反射仅微弱抑制（92±8%）。CPN刺激后，h反射在长时间间隔（> ~ 15ms）显著低于t反射（h反射63 +/- 14%，t反射91 +/- 13%，P < 0.01）。然而，CPN刺激引起的短潜伏期（2 ms）失联Ia互抑对H-和t-反射同样强烈（H-反射72 +/- 10%，t-反射67 +/- 13%；P = 0.07）。跟腱轻敲诱发的单比目鱼肌运动单元（n = 53）放电概率的刺激后时间直方图（PSTH）峰持续时间比胫神经电刺激诱发的峰长（平均5.0 ms比2.7 ms）。调节股二头肌肌腱轻拍后各部位电诱发峰均下降（平均下降为对照组的55 +/- 27%，P < 0.001）。跟腱叩击诱发的峰值在最初2 ms出现了类似的下降（69 +/- 48%;P < 0.001），但在最后2 ms没有下降。长时间间隔（> - 15ms）的CPN调节刺激也降低了电诱发PSTH的所有部分峰值（n = 34，平均65%，P < 0.001），但仅对跟腱轻拍诱发的前2ms峰值有显著影响（85%,P < 0.001）。我们认为，机械和电诱发反射对突触前抑制的不同敏感性是由两种反射背后的兴奋性突触后电位的形状和组成的差异引起的。这种差异可能是由电刺激和机械刺激引起的传入波的不同组成和/或时间分散来解释的。我们的结论是，根据对h反射调制的观察来预测拉伸反射的调制并不简单。
The sensitivity of soleus H-reflexes, T-reflexes, and short-latency stretch reflexes (M1) to presynaptic inhibition evoked by a weak tap applied to the biceps femoris tendon or stimulation of the common peroneal nerve (CPN) was compared in 17 healthy human subjects. The H-reflex was strongly depressed for a period lasting up to 300-400 ms (depression to 48 +/- 23%, mean +/- SD, of control at a conditioning test interval of 70 ms) by the biceps femoris tendon tap. In contrast, the short-latency soleus stretch reflex elicited by a quick passive dorsiflexion of the ankle joint was not depressed. The soleus T-reflex elicited by an Achilles tendon tap was only weakly depressed (92 +/- 8%). The H-reflex was also significantly more depressed than the T-reflex at long intervals (>15 ms) after stimulation of CPN (H-reflex 63 +/- 14%, T-reflex 91 +/- 13%; P < 0.01). However, the short-latency (2 ms) disynaptic reciprocal Ia inhibition evoked by stimulation of CPN was equally strong for H- and T-reflexes (H-reflex 72 +/- 10%, T-reflex 67 +/- 13%; P = 0.07). Peaks in the poststimulus time histogram (PSTH) of the discharge probability of single soleus motor units (n = 53) elicited by an Achilles tendon tap had a longer duration than peaks evoked by electrical stimulation of the tibial nerve ton average 5.0 ms as compared with 2.7 ms). All parts of the electrically evoked peaks were depressed by the conditioning biceps femoris tendon tap (average depression to 55 +/- 27% of control; P < 0.001). A similar depression was observed for the initial 2 ms of the peaks evoked by the Achilles tendon tap (69 +/- 48%; P < 0.001), but the last 2 ms were not depressed. Conditioning stimulation of the CPN at long intervals (>15 ms) also depressed all parts of the electrically evoked PSTH peaks (n = 34; average 65%; P < 0.001) but had only a significant effect on the initial 2 ms of the peaks evoked by the Achilles tendon tap (85%; P < 0.001). We suggest that the different sensitivity of mechanically and electrically evoked reflexes to presynaptic inhibition is caused by a difference in the shape and composition of the excitatory postsynaptic potentials underlying the two reflexes. This difference may be explained by a different composition and/or temporal dispersion of the afferent volleys evoked by electrical and me chanical stimuli. We conclude that it is nor straightforward to predict the modulation of stretch reflexes based on observations of H-reflex modulation.