Zhao Kunkun, He Chuan, Xiang Wentao, Zhou Yuxuan, Zhang Zhisheng, Li Jianqing, Scano Alessandro
School of Biomedical Engineering and Informatics, Nanjing Medical University, Nanjing, Jiangsu, China.
Department of Rehabilitation Medicine, The Affiliated Jiangsu Shengze Hospital of Nanjing Medical University, Suzhou, Jiangsu, China.
Front Physiol. 2023 Sep 11;14:1214995. doi: 10.3389/fphys.2023.1214995. eCollection 2023.
Previous studies showed that the central nervous system (CNS) controls movements by recruiting a low-dimensional set of modules, usually referred to as muscle synergies. Stroke alters the structure and recruitment patterns of muscle synergies, leading to abnormal motor performances. Some studies have shown that muscle synergies can be used as biomarkers for assessing motor function. However, coordination patterns of muscle synergies in post-stroke patients need more investigation to characterize how they are modified in functional movements. Thirteen mild-to-moderate stroke patients and twenty age-matched healthy subjects were recruited to perform two upper-limb movements, hand-to-mouth movement and reaching movement. Muscle synergies were extracted with nonnegative matrix factorization. We identified a set of reference synergies (i.e., averaged across healthy subjects) and typical synergies (i.e., averaged across stroke subjects) from the healthy group and stroke group respectively, and extracted affected synergies from each patient. Synergy similarity between groups was computed and analyzed. Synergy reconstruction analysis was performed to verify synergy coordination patterns in post-stroke patients. On average, three synergies were extracted from both the healthy and stroke groups, while the mild impairment group had a significantly higher number of synergies than the healthy group. The similarity analysis showed that synergy structure was more consistent in the healthy group, and stroke instead altered synergy structure and induced more variability. Synergy reconstruction analysis at group and individual levels showed that muscle synergies of patients often showed a combination of healthy reference synergies in the analyzed movements. Finally, this study associated four synergy coordination patterns with patients: merging (equilibrium and disequilibrium), sharing (equilibrium and disequilibrium), losing, and preservation. The preservation was mainly represented in the mild impairment group, and the moderate impairment group showed more merging and sharing. This study concludes that stroke shows more synergy variability compared to the healthy group and the alterations of muscle synergies can be described as a combination of reference synergies by four synergy coordination patterns. These findings deepen the understanding of the underlying neurophysiological mechanisms and possible motor control strategies adopted by the CNS in post-stroke patients.
先前的研究表明，中枢神经系统（CNS）通过募集一组低维模块来控制运动，这些模块通常被称为肌肉协同作用。中风会改变肌肉协同作用的结构和募集模式，导致运动表现异常。一些研究表明，肌肉协同作用可作为评估运动功能的生物标志物。然而，中风后患者肌肉协同作用的协调模式需要更多研究，以明确其在功能运动中是如何改变的。招募了13名轻度至中度中风患者和20名年龄匹配的健康受试者，让他们进行两种上肢运动，即手到嘴运动和伸手运动。用非负矩阵分解法提取肌肉协同作用。我们分别从健康组和中风组中确定了一组参考协同作用（即健康受试者的平均值）和典型协同作用（即中风受试者的平均值），并从每位患者中提取受影响的协同作用。计算并分析了组间的协同作用相似性。进行了协同作用重建分析，以验证中风后患者的协同作用协调模式。健康组和中风组平均都提取出三种协同作用，而轻度损伤组的协同作用数量显著多于健康组。相似性分析表明，健康组的协同作用结构更一致，而中风则改变了协同作用结构并导致更多变异性。组水平和个体水平的协同作用重建分析表明，患者的肌肉协同作用在分析的运动中常表现为健康参考协同作用的组合。最后，本研究将四种协同作用协调模式与患者相关联：合并（平衡和不平衡）、共享（平衡和不平衡）、丢失和保留。保留主要表现在轻度损伤组，中度损伤组表现出更多的合并和共享。本研究得出结论，与健康组相比，中风表现出更多的协同作用变异性，肌肉协同作用的改变可通过四种协同作用协调模式描述为参考协同作用组合。这些发现加深了对中风后患者中枢神经系统潜在神经生理机制和可能采用的运动控制策略的理解。
