Hasegawa Keita, Kasuga Shoko, Takasaki Kenichi, Mizuno Katsuhiro, Liu Meigen, Ushiba Junichi
Graduate School of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan.
Keio Institute of Pure and Applied Sciences (KiPAS), 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, Japan.
J Neuroeng Rehabil. 2017 Aug 25;14(1):85. doi: 10.1186/s12984-017-0294-2.
Motor planning, imagery or execution is associated with event-related desynchronization (ERD) of mu rhythm oscillations (8-13 Hz) recordable over sensorimotor areas using electroencephalography (EEG). It was shown that motor imagery involving distal muscles, e.g. finger movements, results in contralateral ERD correlating with increased excitability of the contralateral corticospinal tract (c-CST). Following the rationale that purposefully increasing c-CST excitability might facilitate motor recovery after stroke, ERD recently became an attractive target for brain-computer interface (BCI)-based neurorehabilitation training. It was unclear, however, whether ERD would also reflect excitability of the ipsilateral corticospinal tract (i-CST) that mainly innervates proximal muscles involved in e.g. shoulder movements. Such knowledge would be important to optimize and extend ERD-based BCI neurorehabilitation protocols, e.g. to restore shoulder movements after stroke. Here we used single-pulse transcranial magnetic stimulation (TMS) targeting the ipsilateral primary motor cortex to elicit motor evoked potentials (MEPs) of the trapezius muscle. To assess whether ERD reflects excitability of the i-CST, a correlation analysis between between MEP amplitudes and ipsilateral ERD was performed.
Experiment 1 consisted of a motor execution task during which 10 healthy volunteers performed elevations of the shoulder girdle or finger pinching while a 128-channel EEG was recorded. Experiment 2 consisted of a motor imagery task during which 16 healthy volunteers imagined shoulder girdle elevations or finger pinching while an EEG was recorded; the participants simultaneously received randomly timed, single-pulse TMS to the ipsilateral primary motor cortex. The spatial pattern and amplitude of ERD and the amplitude of the agonist muscle's TMS-induced MEPs were analyzed.
ERDs occurred bilaterally during both execution and imagery of shoulder girdle elevations, but were lateralized to the contralateral hemisphere during finger pinching. We found that trapezius MEPs increased during motor imagery of shoulder elevations and correlated with ipsilateral ERD amplitudes.
Ipsilateral ERD during execution and imagery of shoulder girdle elevations appears to reflect the excitability of uncrossed pathways projecting to the shoulder muscles. As such, ipsilateral ERD could be used for neurofeedback training of shoulder movement, aiming at reanimation of the i-CST.
运动计划、想象或执行与通过脑电图（EEG）在感觉运动区可记录的μ节律振荡（8 - 13赫兹）的事件相关去同步化（ERD）有关。研究表明，涉及远端肌肉的运动想象，例如手指运动，会导致对侧ERD，其与对侧皮质脊髓束（c - CST）兴奋性增加相关。基于有目的地增加c - CST兴奋性可能有助于中风后运动恢复的原理，ERD最近成为基于脑机接口（BCI）的神经康复训练的一个有吸引力的目标。然而，尚不清楚ERD是否也能反映主要支配参与例如肩部运动等近端肌肉的同侧皮质脊髓束（i - CST）的兴奋性。这样的知识对于优化和扩展基于ERD的BCI神经康复方案很重要，例如用于中风后恢复肩部运动。在此，我们使用单脉冲经颅磁刺激（TMS）靶向同侧初级运动皮层以引出斜方肌的运动诱发电位（MEP）。为了评估ERD是否反映i - CST的兴奋性，我们对MEP幅度与同侧ERD之间进行了相关性分析。
实验1包括一个运动执行任务，在此期间10名健康志愿者进行肩带抬高或手指捏合动作，同时记录128通道脑电图。实验2包括一个运动想象任务，在此期间16名健康志愿者想象肩带抬高或手指捏合动作，同时记录脑电图；参与者同时接受对同侧初级运动皮层的随机定时单脉冲TMS。分析了ERD的空间模式和幅度以及激动剂肌肉的TMS诱发MEP的幅度。
在肩带抬高的执行和想象过程中，双侧均出现ERD，但在手指捏合时ERD偏向对侧半球。我们发现，在肩部抬高的运动想象过程中斜方肌MEP增加，并且与同侧ERD幅度相关。
在肩带抬高的执行和想象过程中，同侧ERD似乎反映了投射到肩部肌肉的未交叉通路的兴奋性。因此，同侧ERD可用于肩部运动的神经反馈训练，旨在使i - CST恢复活力。
