THE REGULATION OF PRESYNAPTIC INHIBITION DURING COCONTRACTION OF ANTAGONISTIC MUSCLES IN MAN
THE REGULATION OF PRESYNAPTIC INHIBITION DURING COCONTRACTION OF ANTAGONISTIC MUSCLES IN MAN
复制标题
DOI：
10.1113/jphysiol.1993.sp019652
复制
发表时间：
1993-05-01
影响因子：
5.5
通讯作者：
KAGAMIHARA, Y
中科院分区：
文献类型：
--
作者：
NIELSEN, J;KAGAMIHARA, Y
1.在不同水平的肌电图活动踝跖屈和背屈肌的比目鱼肌，胫骨前和内侧腓肠肌H反射的大小进行了测量。在类似水平的肌电图活动在激动剂肌肉，比目鱼肌和胫骨前H反射被发现是较小的共同收缩过程中比在一个孤立的激动剂收缩。与此相反，内侧腓肠肌H反射在共同收缩期间与在可比较的EMG水平下的单独跖屈期间具有相同的大小。峰值出现在单突触反射潜伏期的刺激后时间直方图（PSTH）的发射比目鱼肌和胫骨前运动单位刺激各自的运动神经。这些homoblastic Ia峰被发现在共同收缩比在单独的激动剂收缩，而内侧腓肠肌运动单位是不变的。由于PSTH的单突触峰可以间接测量运动神经元的单突触EPSP的大小，因此这些发现反映了比目鱼肌和胫骨前肌运动单位相对于内侧腓肠肌运动单位的突触前抑制的差异控制.股神经刺激引起的比目鱼肌H反射的单突触LA便利化，也被发现在胫骨前肌和比目鱼肌的共同收缩期间比在孤立跖屈期间更小。这表明，在共收缩过程中，对四头肌向比目鱼肌运动神经元投射的异源性神经纤维的突触前抑制与对同源性神经纤维的突触前抑制的调节方式相同。股神经诱导的单突触促进比目鱼肌H反射被发现减少与增加紧张水平的共同收缩和孤立的背屈和跖屈。促进量下降到相同的程度，增加水平的背屈和共同收缩。因此，在背屈肌肌电水平相同的情况下，背屈肌肌群单独激活或共同收缩时的易化量没有差异。而比目鱼肌H反射的大小增加50毫秒前的动态跖屈的发病，它并没有改变之前的共同收缩的发病。股神经诱导的易化在跖屈前增加，但在共同收缩前减少。这表明，在共同收缩过程中看到的突触前抑制的增加是一个中心的起源。有人建议，增加突触前抑制共收缩过程中观察到的可能是有助于避免激动剂-拮抗剂系统中的振荡。缺乏内侧腓肠肌Ia传入的突触前抑制进行了讨论，其可能的贡献踝关节僵硬。
1. The size of the soleus, tibialis anterior and medial gastrocnemius H reflexes were measured at different levels of EMG activity in ankle plantar- and dorsiflexors. At similar levels of EMG activity in the agonist muscle, the soleus and tibialis anterior H reflexes were found to be smaller during co-contraction than during an isolated agonist contraction. In contrast to this, the medial gastrocnemius H reflex had the same size during co-contraction as during an isolated plantarflexion at comparable EMG levels.2. Peaks occurred at monosynaptic reflex latency in the post-stimulus time histogram (PSTH) of firing of soleus and tibialis anterior motor units following stimulation of their respective motor nerves. These homonymous Ia peaks were found to be smaller during co-contraction than during isolated agonist contraction, whereas that of medial gastrocnemius motor units was unchanged. As the monosynaptic peak in the PSTH may give an indirect measure of the size of the monosynaptic EPSP in the motoneurone, it is suggested that these findings reflect a differential control of presynaptic inhibition of soleus and tibialis anterior motor units with respect to medial gastrocnemius motor units.3. The monosynaptic la facilitation of the soleus H reflex evoked by a stimulation of the femoral nerve, was also found to be smaller during co-contraction of tibialis anterior and soleus than during isolated plantarflexion. This suggests that presynaptic inhibition of heteronymous la fibres from the quadriceps muscle projecting to soleus motoneurones is regulated in the same way as presynaptic inhibition of homonymous Ia fibres during co-contraction.4. The femoral nerve-induced monosynaptic facilitation of the soleus H reflex was found to decrease with increasing tonic levels of both co-contraction and isolated dorsi- and plantarflexion. The amount of facilitation decreased to the same degree with increasing levels of dorsiflexion and co-contraction. For the same level of EMG in the dorsiflexors there was thus no difference in the amount of facilitation whether the dorsiflexors were activated separately or in a co-contraction.5. Whereas the soleus H reflex increased in size 50 ms prior to the onset of a dynamic plantarflexion, it did not change prior to the onset of a co-contraction. The femoral nerve-induced facilitation increased prior to the plantarflexion, but decreased prior to the co-contraction. This suggests that the increase of presynaptic inhibition seen during co-contraction is of a central origin.6. It is suggested that the increase of presynaptic inhibition observed during co-contraction may be instrumental in avoiding oscillations in the agonist-antagonist system. The lack of presynaptic inhibition of medial gastrocnemius Ia afferents is discussed in relation to its possible contribution to the ankle joint stiffness.