Neuroplasticity and Motor Behavior Laboratory, Moss Rehabilitation Research Institute, Elkins Park, PA, United States; Department of Physical Therapy, Arcadia University, Glenside, PA, United States.
Neuroplasticity and Motor Behavior Laboratory, Moss Rehabilitation Research Institute, Elkins Park, PA, United States.
Neurosci Lett. 2020 Feb 16;720:134751. doi: 10.1016/j.neulet.2020.134751. Epub 2020 Jan 10.
Bilateral activation in motor cortex is observed during paretic hand performance after stroke; however the functional significance of contralesional motor cortex (C-M1) activation is highly debated. Particularly, it is not known if task characteristics such as dexterity influence the causal engagement of C-M1 during paretic hand performance. Transcranial magnetic stimulation (TMS) was used to quantify motor corticospinal physiology of the CM1 projecting to the contralateral resting extensor carpi radialis brevis (ECRB) and first dorsal interosseous (FDI) while eleven participants with unilateral stroke performed unimanual tasks of differing dexterity with their paretic hand. The novel finding was that compared to rest and less dexterous task (LDT), more dexterous task (MDT) performance led to increased corticospinal excitability and decreased intracortical inhibition of the C-M1 projecting to the resting FDI, but not resting ECRB. Further, using trains of repetitive TMS during MDT and LDT, we tested the behavioral relevance of C-M1 for paretic hand performance. Online rTMS perturbation to C-M1, but not to the vertex or sham stimulation led to significantly more movement errors during MDT without consistently affecting LDT performance. The present results argue for a beneficial role of C-M1 for accurate performance during dexterous motor actions with the paretic hand after stroke.
在脑卒中后，瘫痪手进行运动时会观察到运动皮层的双侧激活；然而，对健侧运动皮层（C-M1）激活的功能意义存在很大争议。特别是，尚不清楚任务特征（如灵巧性）是否会影响瘫痪手运动过程中 C-M1 的因果参与。我们使用经颅磁刺激（TMS）来量化 11 名单侧脑卒中患者瘫痪手进行不同灵巧性的单侧任务时，C-M1 投射到对侧静息桡侧腕短伸肌（ECRB）和第一背侧骨间肌（FDI）的运动皮质脊髓生理学。一个新的发现是，与休息和不太灵巧的任务（LDT）相比，更灵巧的任务（MDT）会导致投射到静息 FDI 的 C-M1 的皮质脊髓兴奋性增加和抑制性降低，但对静息 ECRB 没有影响。此外，我们在 MDT 和 LDT 期间使用重复 TMS 进行训练，以测试 C-M1 对瘫痪手运动的行为相关性。在 MDT 期间，对 C-M1 进行在线 rTMS 干扰，而不是对顶点或假刺激进行在线 rTMS 干扰，会导致运动错误明显增加，而不会持续影响 LDT 表现。本研究结果表明，在脑卒中后用瘫痪手进行灵巧运动动作时，C-M1 对准确运动具有有益作用。
