Posture-related changes in heteronymous recurrent inhibition from quadriceps to ankle muscles in humans
Posture-related changes in heteronymous recurrent inhibition from quadriceps to ankle muscles in humans
复制标题
DOI：
10.1007/s002219900260
复制
发表时间：
2000-02-01
影响因子：
2
通讯作者：
Pierrot-Deseilligny, E
中科院分区：
文献类型：
--
作者：
Barbeau, H;Marchand-Pauvert, V;Pierrot-Deseilligny, E
我们研究了从股四头肌(Q)到比目鱼肌（Sol）和胫骨前肌（TA）运动神经元（MNs）的异位复发抑制（RI）在需要用其中一块肌肉收缩Q的姿势任务中发生变化的可能性。刺激股神经（FN），引起Q h反射放电，用于激活Renshaw细胞。由此产生的TA和Sol MNs的抑制作用通过三个测试反应来评估：(1)TA或Sol的校正和平均持续肌电图（EMG）活动；(2)皮层刺激引起的运动诱发电位（MEP）；(3) Sol H反射。该凹陷的特征（随条件反射放电而出现和增加，中枢延迟短，持续时间长）符合Renshaw起源。此外，在对照实验中获得的结果（缺血阻断来自腿部的i组传入事件后，肌电图抑制没有变化，FN诱导的MEP抑制的时间过程与正在进行的肌电图相似）表明，FN刺激激活的其他途径不太可能起到重要作用。在不同的姿势任务中，比较了背景EMC活动水平相匹配时Q的姿势相关异位RI。坐位时Q和相关踝关节肌肉的自愿共同收缩（控制情况），Q和TA的体位性共同收缩（站立时向后倾斜），或者有（准备跳跃）和没有（站立时踮起脚尖和前倾）Q相关收缩时的Sol收缩（站立时）。在站立时，从Q的异位RI在向后倾斜和准备跳跃时减少到TA（但不是到Sol）。但在其他情况下不是这样。因此，当需要收缩Q和踝关节处的相关肌肉以维持双足站立时，从Q到TA或Sol的RI会明显减少。有人认为，这种对Renshaw细胞的控制是从起源上下降的，并有助于在各种姿势任务中选择适当的协同作用。
The possibility was investigated that changes in heteronymous recurrent inhibition (RI) from quadriceps (Q) to soleus (Sol) and tibialis anterior (TA) motoneurons (MNs) occur during postural tasks requiring cocontraction of Q with one of these muscles. Stimulation of the femoral nerve (FN), which elicited a Q H-reflex discharge, was used to activate Renshaw cells. The resulting inhibition of TA and Sol MNs was assessed using three test responses: (1) the rectified and averaged ongoing electromyogram (EMG) activity in TA or Sol; (2) the motor-evoked potential (MEP) elicited by cortical stimulation in these muscles; and (3) the Sol H reflex. The characteristics of the depression (appearance and increase with the conditioning reflex discharge, short central delay and long duration) are consistent with a Renshaw origin. In addition, results obtained in control experiments (no change in the EMG suppression after an ischaemic blockade of group-I afferents from the leg, time course of the FN-induced depression of the MEP similar to that of the ongoing EMG) made a significant contribution from other pathways activated by FN stimulation unlikely. Posture-related heteronymous RI from Q was compared in different postural tasks at matched levels of background EMC activity: voluntary co-contraction of Q and of the relevant ankle muscle while sitting (control situation), postural co-contraction of Q and TA (while leaning backwards during stance), or contraction of Sol with (preparation for hopping) and without (standing on tip of toes and leaning forwards during stance) associated contraction of the Q. During stance, heteronymous RI from Q was reduced to TA (but not to Sol) while leaning backwards and to Sol in preparation for hopping, but not in the other situations. Thus, RI from Q to TA or Sol was specifically decreased when a cocontraction of the Q and of the relevant muscle operating at the ankle was required to maintain bipedal stance. It is argued that this control of Renshaw cells is descending in origin and contributes to selection of the appropriate synergism in various postural tasks.