Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong, People's Republic of China.
University Research Facility in Behavioural and Systems Neuroscience (UBSN), The Hong Kong Polytechnic University, Hong Kong, People's Republic of China.
J Neural Eng. 2021 Sep 21;18(5). doi: 10.1088/1741-2552/ac20bc.
Proximal-to-distal compensation is commonly observed in the upper extremity (UE) after a stroke, mainly due to the impaired fine motor control in hand joints. However, little is known about its related neural reorganization. This study investigated the pathway-specific corticomuscular interaction in proximal-to-distal UE compensation during fine motor control of finger extension post-stroke by directed corticomuscular coherence (dCMC).We recruited 14 chronic stroke participants and 11 unimpaired controls. Electroencephalogram (EEG) from the sensorimotor area was concurrently recorded with electromyography (EMG) from extensor digitorum (ED), flexor digitorum (FD), triceps brachii (TRI) and biceps brachii (BIC) muscles in both sides of the stroke participants and in the dominant (right) side of the controls during the unilateral isometric finger extension at 20% maximal voluntary contractions. The dCMC was analyzed in descending (EEG → EMG) and ascending pathways (EMG → EEG) via the directed coherence. It was also analyzed in stable (segments with higher EMG stability) and less-stable periods (segments with lower EMG stability) subdivided from the whole movement period to investigate the fine motor control. Finally, the corticomuscular conduction time was estimated by dCMC phase delay.The affected limb had significantly lower descending dCMC in distal UE (ED and FD) than BIC (< 0.05). It showed the descending dominance (significantly higher descending dCMC than the ascending,< 0.05) in proximal UE (BIC and TRI) rather than the distal UE as in the controls. In the less-stable period, the affected limb had significantly lower EMG stability but higher ascending dCMC (< 0.05) in distal UE than the controls. Furthermore, significantly prolonged descending conduction time (∼38.8 ms) was found in ED in the affected limb than the unaffected (∼26.94 ms) and control limbs (∼25.74 ms) (< 0.05).The proximal-to-distal UE compensation in fine motor control post-stroke exhibited altered descending dominance from the distal to proximal UE, increased ascending feedbacks from the distal UE for fine motor control, and prolonged descending conduction time in the agonist muscle.
上肢（UE）在卒中后常发生由近及远的补偿，主要是由于手部关节精细运动控制受损。然而，其相关的神经重组知之甚少。本研究通过定向皮质肌相干（dCMC）探讨卒中后手指伸展精细运动控制时 UE 由近及远补偿的近端到远端的特定皮质肌相互作用。
我们招募了 14 名慢性卒中参与者和 11 名未受损的对照者。在参与者的卒中侧和对照者的优势（右侧）记录伸展指肌（ED）、屈指肌（FD）、肱三头肌（TRI）和肱二头肌（BIC）的肌电图（EMG）的同时，记录来自感觉运动区的脑电图（EEG），进行单侧等长手指伸展至 20%最大随意收缩力。通过定向相干分析下行（EEG→EMG）和上行（EMG→EEG）通路的 dCMC。还分析了整个运动期间分为稳定（EMG 稳定性较高的片段）和不稳定（EMG 稳定性较低的片段）两个阶段，以研究精细运动控制。最后，通过 dCMC 相位延迟估计皮质肌传导时间。
与健侧相比，患侧远侧 UE（ED 和 FD）的下行 dCMC 显著降低（<0.05）。与对照组相比，近端 UE（BIC 和 TRI）的下行优势更为明显（下行 dCMC 显著高于上行，<0.05）。在不稳定期，患侧远侧 UE 的 EMG 稳定性显著降低，但上行 dCMC 显著升高（<0.05），与对照组相比。此外，与健侧（约 26.94 ms）和对照组（约 25.74 ms）相比，患侧 ED 的下行传导时间显著延长（约 38.8 ms）（<0.05）。
卒中后精细运动控制的 UE 由近及远补偿表现为从远侧 UE 到近端 UE 的下行优势改变，远侧 UE 对精细运动控制的上行反馈增加，以及激动肌的下行传导时间延长。
