Voigt M, Sinkjaer T
Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark.
Brain Res. 1998 Feb 9;783(2):332-46. doi: 10.1016/s0006-8993(97)01389-9.
The purpose of the present study was to investigate the influence of afferent activity (mainly homonymous Ia-afferent activity) on the modulation (post-activation depression) of the soleus H-reflex during isolated and passive sinusoidal ankle joint rotations at a speed and amplitude comparable to slow walking. The H-reflex modulation was measured in the relaxed soleus muscle on human subjects during different imposed patterns of 20 degrees haversine ankle joint rotations (0.5-0.6 Hz) while they were sitting comfortably in a chair. Eighteen healthy males and four male patients with clinically complete spinal cord lesion above the soleus motoneuron pool participated in the study. During a single dorsi-plantar flexion rotation the H-reflex was depressed to 27+/-7% (mean+/-S.E.M.) of the initial level within 600 ms. The course of this depression was reversed when the dorsi-flexion velocity started to decrease. At the end of the dorsi-flexion movement the depression was already relieved to a level of 73+/-6% of the initial level. The H-reflex returned more slowly to the initial level within 2 s after the end of the movement cycle. During two consecutive ankle joint rotations and continuous ankle joint rotations both at 0.5 Hz the H-reflex was modulated but also generally depressed while the movement was imposed. The reflex only returned to the reference level after the movements were stopped. These observations indicate the action of a fast and a slow mechanism in the post-activation depression of the soleus H-reflex. The H-reflex modulations observed in the spinal cord injured patients were comparable to the reflex modulations observed in the healthy subjects, except the depressions were smaller. This suggests that a major part of the amplitude of the H-reflex modulation observed in healthy subjects was caused by peripheral and spinal influences. The fast 500 ms recovery of the H-reflex had a time course comparable to presynaptic inhibition. The slow 2 s recovery after the end of a given imposed movement may be explained by a change in the probability of transmitter release from the homonymous soleus Ia-afferent synaptic terminals after repeated activations.
本研究的目的是，在与慢走速度和幅度相当的情况下，于孤立和被动正弦踝关节旋转过程中，研究传入活动（主要是同名Ia类传入活动）对比目鱼肌H反射调制（激活后抑制）的影响。在人类受试者舒适地坐在椅子上时，以不同的施加模式进行20度正弦踝关节旋转（0.5 - 0.6 Hz），并测量其放松比目鱼肌中的H反射调制。18名健康男性和4名比目鱼肌运动神经元池以上临床完全性脊髓损伤的男性患者参与了该研究。在单次背屈 - 跖屈旋转过程中，H反射在600毫秒内降至初始水平的27±7%（平均值±标准误）。当背屈速度开始下降时，这种抑制过程发生逆转。在背屈运动结束时，抑制已减轻至初始水平的73±6%。运动周期结束后2秒内，H反射恢复到初始水平的速度较慢。在0.5 Hz的连续两次踝关节旋转和连续踝关节旋转过程中，施加运动时H反射都受到调制，但总体上也受到抑制。只有在运动停止后，反射才恢复到参考水平。这些观察结果表明，在比目鱼肌H反射激活后抑制过程中存在快速和慢速机制。在脊髓损伤患者中观察到的H反射调制与在健康受试者中观察到的反射调制相当，只是抑制程度较小。这表明，健康受试者中观察到的H反射调制幅度的主要部分是由外周和脊髓影响引起的。H反射快速的500毫秒恢复过程与突触前抑制的时间进程相当。给定施加运动结束后缓慢的2秒恢复可能是由于同名比目鱼肌Ia类传入突触末端在反复激活后递质释放概率发生了变化。
