Department of Physical Therapy, Yamagata Prefectural University of Health Sciences, 260 Kamiyanagi, Yamagata, 990-2212, Japan.
Department of Anatomy and Structural Science, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata, 990-9585, Japan.
BMC Neurosci. 2021 Oct 13;22(1):61. doi: 10.1186/s12868-021-00665-w.
Sensory input via neuromuscular electrical stimulation (NMES) may contribute to synchronization between motor cortex and spinal motor neurons and motor performance improvement in healthy adults and stroke patients. However, the optimal NMES parameters used to enhance physiological activity and motor performance remain unclear. In this study, we focused on sensory feedback induced by a beta-band frequency NMES (β-NMES) based on corticomuscular coherence (CMC) and investigated the effects of β-NMES on CMC and steady-state of isometric ankle dorsiflexion in healthy volunteers. Twenty-four participants received β-NMES at the peak beta-band CMC or fixed NMES (f-NMES) at 100 Hz on different days. NMES was applied to the right part of the common peroneal nerve for 20 min. The stimulation intensity was 95% of the motor threshold with a pulse width of 1 ms. The beta-band CMC and the coefficient of variation of force (Force CV) were assessed during isometric ankle dorsiflexion for 2 min. In the complementary experiment, we applied β-NMES to 14 participants and assessed beta-band CMC and motor evoked potentials (MEPs) with transcranial magnetic stimulation.
No significant changes in the means of beta-band CMC, Force CV, and MEPs were observed before and after NMES conditions. Changes in beta-band CMC were correlated to (a) changes in Force CV immediately, at 10 min, and at 20 min after β-NMES (all cases, p < 0.05) and (b) changes in MEPs immediately after β-NMES (p = 0.01). No correlations were found after f-NMES.
Our results suggest that the sensory input via NMES was inadequate to change the beta-band CMC, corticospinal excitability, and voluntary motor output. Whereas, the β-NMES affects the relationship between changes in beta-band CMC, Force CV, and MEPs. These findings may provide the information to develop NMES parameters for neurorehabilitation in patients with motor dysfunction.
通过神经肌肉电刺激（NMES）进行感觉输入可能有助于健康成年人和中风患者的运动皮层和脊髓运动神经元之间的同步，并改善运动表现。然而，用于增强生理活动和运动表现的最佳 NMES 参数仍不清楚。在这项研究中，我们专注于基于皮质肌相干性（CMC）的β波段频率 NMES（β-NMES）引起的感觉反馈，并研究了β-NMES 对 CMC 和健康志愿者等速踝背屈稳态的影响。24 名参与者在不同的日子里接受了β-NMES 在β波段 CMC 峰值或固定 NMES（f-NMES）在 100Hz。NMES 施加于右侧腓总神经，持续 20 分钟。刺激强度为运动阈值的 95%，脉冲宽度为 1ms。在等速踝背屈 2 分钟期间评估β波段 CMC 和力的变异系数（Force CV）。在补充实验中，我们对 14 名参与者应用β-NMES，并使用经颅磁刺激评估β波段 CMC 和运动诱发电位（MEPs）。
NMES 前后，β波段 CMC、Force CV 和 MEPs 的平均值均无明显变化。β波段 CMC 的变化与（a）β-NMES 后立即、10 分钟和 20 分钟时 Force CV 的变化相关（所有情况，p<0.05），以及（b）β-NMES 后立即的 MEPs 变化相关（p=0.01）。在 f-NMES 后未发现相关性。
我们的研究结果表明，NMES 引起的感觉输入不足以改变β波段 CMC、皮质脊髓兴奋性和自主运动输出。然而，β-NMES 影响β波段 CMC、Force CV 和 MEPs 变化之间的关系。这些发现可能为开发用于运动功能障碍患者神经康复的 NMES 参数提供信息。
