Amplitude modulation of the soleus H-reflex in the human during walking and standing
Amplitude modulation of the soleus H-reflex in the human during walking and standing
复制标题
人类行走和站立时比目鱼肌 H 反射的幅度调制
作者：
C. Capaday;R. Stein
进行实验，以确定在步骤周期的各个阶段的比目鱼肌的单突触介导的H-反射的振幅，使用基于计算机的分析程序。在所有受试者中，H反射的振幅在行走周期期间的振幅中被强烈调制，并且在站立阶段期间最高。在许多受试者中，反射振幅的峰值与比目鱼肌肌电图（EMG）活动的峰值同时出现，但在其他受试者中，反射振幅的峰值出现得更早。反射变化的形式（即，在步进周期期间的H反射幅度与周期中的相位的包络）也可以与步进期间产生的EMG的包络完全不同。在相同的刺激强度和EMG水平，H反射总是更大，高达3.5倍，在稳定保持收缩，而站在比在步行。受试者站立时的大反射与在这项任务中保持稳定姿势所需的位置控制一致。类似地，行走期间的反射在站立阶段期间最大，此时它们将帮助保持身体对抗重力的直立位置。在摆动阶段，当它们反对踝关节屈曲时，反射最小。然而，由于反射幅度是任务相关的（即，在相同的EMG和刺激水平下，站立期间比行走期间更大），并且并不总是与在给定任务（例如行走）期间产生的EMG密切相关，因此行走期间H反射的强调制不仅仅是α-运动神经元兴奋水平的被动结果。（250字处删节）
Experiments were done to determine the amplitude of the monosynaptically mediated H-reflex of the soleus muscle at various phases of the step cycle, using a computer-based analysis procedure. In all subjects tested the amplitude of the H-reflex was strongly modulated in amplitude during the walking cycle and was highest during the stance phase. In many subjects the peak reflex amplitude occurred at about the same time as the peak soleus electromyographic (EMG) activity, but in others it occurred earlier. The form of the reflex variation (i.e., envelope of H-reflex amplitude versus phase in cycle) during the step cycle could also be quite different from that of the EMG produced during stepping. At an equal stimulus strength and EMG level, the H-reflex was always much larger, up to 3.5 X, during steadily maintained contractions while standing than during walking. The large reflexes when subjects were standing are consistent with the control of position required to maintain a stable posture in this task. Similarly, the reflexes during walking are greatest during the stance phase, when they will assist in maintaining the upright position of the body against gravity. The reflexes are smallest during the swing phase when they would oppose ankle flexion. However, since the reflex amplitude is task-dependent (i.e., greater during standing than during walking at the same EMG and stimulus levels) and is not always closely related to the EMG produced during a given task such as walking, the strong modulation of H-reflex during walking is not simply a passive consequence of the alpha-motoneuron excitation level.(ABSTRACT TRUNCATED AT 250 WORDS)