BACKGROUND Neuromuscular electrical stimulation (NMES) is extensively used in stroke motor rehabilitation. How it promotes motor recovery remains only partially understood. NMES could change muscular properties, produce altered sensory inputs, and modulate fluctuations of cortical activities; but the potential contribution from cortico-muscular couplings during NMES synchronized with dynamic movement has rarely been discussed. METHOD We investigated cortico-muscular interactions during passive, active, and NMES rhythmic pedaling in healthy subjects and chronic stroke survivors. EEG (128 channels), EMG (4 unilateral lower limb muscles) and movement parameters were measured during 3 sessions of constant-speed pedaling. Sensory-level NMES (20 mA) was applied to the muscles, and cyclic stimulation patterns were synchronized with the EMG during pedaling cycles. Adaptive mixture independent component analysis was utilized to determine the movement-related electro-cortical sources and the source dipole clusters. A directed cortico-muscular coupling analysis was conducted between representative source clusters and the EMGs using generalized partial directed coherence (GPDC). The bidirectional GPDC was compared across muscles and pedaling sessions for post-stroke and healthy subjects. RESULTS Directed cortico-muscular coupling of NMES cycling was more similar to that of active pedaling than to that of passive pedaling for the tested muscles. For healthy subjects, sensory-level NMES could modulate GPDC of both ascending and descending pathways. Whereas for stroke survivors, NMES could modulate GPDC of only the ascending pathways. CONCLUSIONS By clarifying how NMES influences neuromuscular control during pedaling in healthy and post-stroke subjects, our results indicate the potential limitation of sensory-level NMES in promoting sensorimotor recovery in chronic stroke survivors.

中文翻译：

---

慢性中风幸存者踩踏板时神经肌肉电刺激的通路特异性调节作用。

背景技术神经肌肉电刺激（NMES）被广泛用于中风运动康复中。它如何促进运动恢复还只有部分了解。NMES可以改变肌肉特性，产生变化的感觉输入，并调节皮层活动的波动；但是在NMES与动态运动同步的过程中，皮层-肌肉耦合的潜在贡献很少被讨论。方法我们调查了健康受试者和慢性卒中幸存者在被动，主动和NMES有节奏的蹬踏过程中的皮质肌肉相互作用。在3次等速踩踏过程中测量了EEG（128个通道），EMG（4个单侧下肢肌肉）和运动参数。将感觉水平的NMES（20 mA）应用于肌肉，在蹬踏周期中，周期性刺激模式与肌电图同步。利用自适应混合物独立成分分析来确定与运动有关的电皮层源和源偶极子簇。使用广义部分定向相干性（GPDC）在代表性来源簇和EMG之间进行了定向皮层-肌肉耦合分析。对于卒中后和健康受试者，比较了双向GPDC在肌肉和蹬踏过程中的表现。结果NMES自行车的直接皮质肌肉耦合与主动踩踏相比，与被动踩踏的测试肌肉更相似。对于健康受试者，感官水平的NMES可以调节GPDC的上升和下降路径。而对于中风幸存者，NMES只能调节GPDC的上升途径。结论通过阐明NMES如何影响健康和中风受试者在踩踏过程中的神经肌肉控制，我们的结果表明，感觉水平的NMES在促进慢性中风幸存者感觉运动恢复方面可能存在局限性。