Nojima Ippei, Watanabe Tatsunori, Saito Kotaro, Tanabe Shigeo, Kanazawa Hoshinori
Department of Physical Therapy, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Japan Society for the Promotion of Science, Tokyo, Japan.
Front Hum Neurosci. 2018 Feb 13;12:50. doi: 10.3389/fnhum.2018.00050. eCollection 2018.
The voluntary step execution task is a popular measure for identifying fall risks among elderly individuals in the community setting because most falls have been reported to occur during movement. However, the neurophysiological functions during this movement are not entirely understood. Here, we used electromyography (EMG) to explore the relationship between EMG-EMG coherence, which reflects common oscillatory drive to motoneurons, and motor performance associated with stepping tasks: simple reaction time (SRT) and choice reaction time (CRT) tasks. Ten healthy elderly adults participated in the study. Participants took a single step forward in response to a visual imperative stimulus. EMG-EMG coherence was analyzed for 1000 ms before the presentation of the stimulus (stationary standing position) from proximal and distal tibialis anterior (TA) and soleus (SOL) muscles. The main result showed that all paired EMG-EMG coherences in the alpha and beta frequency bands were greater in the SRT than the CRT task. This finding suggests that the common oscillatory drive to the motoneurons during the SRT task occurred prior to taking a step, whereas the lower value of corticospinal activity during the CRT task prior to taking a step may indicate an involvement of inhibitory activity, which is consistent with observations from our previous study (Watanabe et al., 2016). Furthermore, the beta band coherence in intramuscular TA tended to positively correlate with the number of performance errors that are associated with fall risks in the CRT task, suggesting that a reduction in the inhibitory activity may result in a decrease of stepping performance. These findings could advance the understanding of the neurophysiological features of postural adjustments in elderly individuals.
自愿步行动作执行任务是一种在社区环境中识别老年人跌倒风险的常用方法，因为据报道大多数跌倒发生在移动过程中。然而，人们对这一运动过程中的神经生理功能尚未完全了解。在此，我们使用肌电图（EMG）来探究肌电图-肌电图相干性（反映运动神经元的共同振荡驱动）与步行动作任务相关的运动表现之间的关系：简单反应时间（SRT）任务和选择反应时间（CRT）任务。十名健康的老年人参与了这项研究。参与者在视觉指令刺激下向前迈出一步。在刺激呈现前1000毫秒（静止站立姿势），对胫前肌（TA）近端和远端以及比目鱼肌（SOL）的肌电图-肌电图相干性进行分析。主要结果表明，在α和β频段，所有配对的肌电图-肌电图相干性在SRT任务中均高于CRT任务。这一发现表明，在SRT任务中运动神经元的共同振荡驱动发生在迈步之前，而在CRT任务中迈步前皮质脊髓活动较低的值可能表明存在抑制性活动的参与，这与我们之前的研究（渡边等人，2016年）的观察结果一致。此外，肌内TA的β频段相干性往往与CRT任务中与跌倒风险相关的表现错误数量呈正相关，这表明抑制性活动的减少可能导致步行动作表现下降。这些发现有助于增进对老年人姿势调整神经生理特征的理解。
