Ruegg D G
Institute of Physiology, University of Fribourg, Switzerland.
Exp Brain Res. 1989;74(3):663-6. doi: 10.1007/BF00247372.
The aim of the present investigation was to study whether the pre-movement inhibition of the H reflex in the antagonist of a ballistic voluntary contraction was due to a reduced activity of the motoneuronal pool of the antagonist, or to a reduced excitatory effect of the afferent volley reaching these motoneurons. Human subjects performed visually conditioned ballistic dorsal flexions of the ankle. The inhibition of the H reflex in the antagonist (soleus muscle) was similar if the muscle was initially relaxed or if there was a preexisting level of motor discharge. Since the soleus muscle was inhibited before movement onset in parallel with the H reflex inhibition, the relation between the level of a background activity and the size of superimposed H reflexes was studied. The finding that H reflexes were only slightly reduced in size with decreasing steady EMG levels could not explain the pre-movement inhibition, and it was concluded than an increased presynaptic inhibition of Ia terminals was the source of the H reflex inhibition.
本研究的目的是探讨在弹道式随意收缩的拮抗肌中，H反射的运动前抑制是由于拮抗肌运动神经元池的活动降低，还是由于到达这些运动神经元的传入冲动的兴奋性效应降低。人类受试者进行视觉条件化的踝关节背屈弹道运动。如果肌肉最初是放松的，或者存在预先存在的运动放电水平，拮抗肌（比目鱼肌）中H反射的抑制是相似的。由于比目鱼肌在运动开始前与H反射抑制同时受到抑制，因此研究了背景活动水平与叠加的H反射大小之间的关系。随着稳定肌电图水平的降低，H反射大小仅略有减小这一发现无法解释运动前抑制，得出的结论是，Ia终末突触前抑制增加是H反射抑制的来源。
