MONO-SYNAPTIC AND OLIGOSYNAPTIC CONTRIBUTIONS TO HUMAN ANKLE JERK AND H-REFLEX
MONO-SYNAPTIC AND OLIGOSYNAPTIC CONTRIBUTIONS TO HUMAN ANKLE JERK AND H-REFLEX
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DOI：
10.1152/jn.1984.52.3.435
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发表时间：
1984-01-01
影响因子：
2.5
通讯作者：
MCKEON, B
中科院分区：
文献类型：
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作者：
BURKE, D;GANDEVIA, SC;MCKEON, B
在正常受试者中研究了寡突触反射通路是否可能影响踝反射中的运动神经元放电和比目鱼肌的 H 反射。如果由肌腱冲击或电刺激周围神经产生的比目鱼肌运动神经元池兴奋性增加的上升阶段持续超过几毫秒，并且如果兴奋性的增加需要几毫秒才能达到运动神经元放电的阈值，则这些反射不可能完全是单突触的。在放松受试者中，使用略低于阈值的条件刺激和略高于反射反应阈值的测试 H 反射来检查由腱冲击产生的比目鱼肌运动神经元池的兴奋性变化。兴奋性增加的平均上升时间为 10.8 毫秒，总持续时间为 .apprx。 25 毫秒在单运动单位中，通过阈下肌腱敲击和阈下胫神经电刺激建立的复合兴奋性突触后电位（EPSP）的上升时间是根据自愿激活的单运动单位放电概率的变化来估计的。肌腱冲击的上升时间明显长于电刺激。在 4 个实验中，使用相同的机械和电刺激对许多运动单位进行了研究。将每次刺激的刺激后时间直方图 (PSTH) 合并起来，以提供运动神经元池中兴奋性变化的上升时间的估计。这 4 个样本的平均上升时间在机械刺激下为 10.5 毫秒，在电刺激下为 4.5 毫秒。在 6 个运动单位中，反射放电潜伏期的自发变异性与放电概率增加的持续时间相比较小。在这两种反射中，尽管 EPSP 上升时间较长，但运动单位肌电电位的潜伏期几乎没有分散。腱反射具有复合 EPSP，其上升阶段持续 10 毫秒，其中大部分用于将运动神经元膜电位提高至阈值。运动神经元在 EPSP 的后半部分放电，即单突触兴奋开始后几毫秒。寡突触通路可能影响踝反射中的运动神经元放电和 H 反射的变化。
Whether it is possible for oligosynaptic reflex pathways to affect motoneuron discharge in the ankle jerk and H-reflex of the soleus was studied in normal subjects. If the rising phase of the increase in excitability of the soleus motoneuron pool produced by tendon percussion or by electrical stimulation of the peripheral nerve lasts more than a few milliseconds, and if the increase in excitability takes several milliseconds to reach the threshold for motoneuron discharge, these reflexes are unlikely to be exclusively monosynaptic. In relaxes subjects, changes in excitability of the soleus motoneuron pool produced by tendon percussion were examined using conditioning stimuli just below threshold and a test H-reflex just above threshold for a reflex response. The increase in excitability had an average rise time of 10.8 ms and a total duration of .apprx. 25 ms. In single motor units, the rise times of the composite excitatory postsynaptic potentials (EPSP) set up by subthreshold tendon percussion and by subthreshold electrical stimulation of the tibial nerve were estimated from changes in the probability of discharge of voluntarily activated single motor units. Rise times were significantly longer with tendon percussion than with electrical stimulation. In 4 experiments, a number of motor units were studied using identical mechanical and electrical stimuli. The poststimulus time histograms (PSTH) for each stimulus were pooled to provide an estimate of the rise time of the excitability change in the motoneuron pool. The mean rise times of these 4 samples were 10.5 ms with mechanical stimulation and 4.5 ms with electrical stimulation. In 6 motor units, the spontaneous variability in latency of the reflex discharges was small compared to the duration of the increase in probability of discharge. In both reflexes, there was little dispersion in the latencies of motor-unit electromyographic potentials despite the long EPSP rise times. The tendon jerk has a composite EPSP with a rising phase lasting 10 ms, much of which is spent raising the motoneuron membrane potential to threshold. Motoneurons discharge in the last half of the EPSP, some milliseconds after the onset of monosynaptic excitation. Oligosynaptic pathways may affect motoneuron discharge in the ankle jerk and changes in the H-reflex.