Osaka Prefecture University.
Motor Control. 2020 Jan 24;24(2):253-273. doi: 10.1123/mc.2019-0042.
This study investigated the effect of the time and direction preparation on the electromyographic (EMG) response of the ankle extensor to the backward translation of the support surface in stance. Fifteen healthy adult males aged 35.9 ± 6.2 years participated in this study. In the constant session, the interval between the warning cue and the onset of the backward support surface translation was constant. In the random time session, the interval was randomly assigned in each trial, but the direction was backward across the trials. In the random direction session, the direction was randomly assigned in each trial, but the interval was constant. The EMG amplitude in the time epochs 100-175 ms after translation onset in the random time session was significantly greater than that in the constant session in the soleus, gastrocnemius, and tibialis anterior muscles. The EMG amplitude in the time epochs 120-185 ms after translation onset in the random direction session was significantly greater than that in the constant session in the gastrocnemius and tibialis anterior muscles. This finding indicates that time and direction preparation reduces the late component of the ankle EMG response to backward translation of the support surface. This finding is explained by the supposed process through which uncertainty of the upcoming event causes disinhibition of response or by how time and direction preparation optimizes the magnitude of the long-latency response mediated by the transcortical pathway.
本研究旨在探讨在站立位支撑面向后平移时，时间和方向准备对踝关节伸肌肌电（EMG）反应的影响。15 名健康成年男性，年龄 35.9±6.2 岁，参与了本研究。在恒定间隔组中，警告提示与支撑面向后平移开始之间的间隔是固定的。在随机时间间隔组中，每个试验的间隔是随机分配的，但试验之间的方向是向后的。在随机方向间隔组中，每个试验的方向是随机分配的，但间隔是固定的。在随机时间间隔组中，平移开始后 100-175ms 的时间窗内，比目鱼肌、腓肠肌和胫骨前肌的 EMG 振幅明显大于恒定间隔组。在随机方向间隔组中，平移开始后 120-185ms 的时间窗内，腓肠肌和胫骨前肌的 EMG 振幅明显大于恒定间隔组。这一发现表明，时间和方向准备减少了支撑面向后平移时踝关节 EMG 反应的晚期成分。这一发现可以通过即将发生的事件的不确定性导致反应去抑制的假设过程来解释，或者通过时间和方向准备如何优化经皮质途径介导的长潜伏期反应的幅度来解释。
