Vasilyev Anatoly N, Nuzhdin Yury O, Kaplan Alexander Y
Department of Human and Animal Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia.
MEG Center, Moscow State University of Psychology and Education, 123290 Moscow, Russia.
Brain Sci. 2021 Sep 18;11(9):1234. doi: 10.3390/brainsci11091234.
Motor imagery engages much of the same neural circuits as an overt movement. Therefore, the mental rehearsal of movements is often used to supplement physical training and might aid motor neurorehabilitation after stroke. One attempt to capture the brain's involvement in imagery involves the use, as a marker, of the depression or event-related desynchronization (ERD) of thalamocortical sensorimotor rhythms found in a human electroencephalogram (EEG). Using fast real-time processing, it is possible to make the subject aware of their own brain reactions or-even better-to turn them into actions through a technology called the brain-computer interface (BCI). However, it remains unclear whether BCI-enabled imagery facilitates a stronger or qualitatively different brain response compared to the open-loop training.
Seven healthy volunteers who were experienced in both closed and open-loop motor imagery took part in six experimental sessions over a period of 4.5 months, in which they performed kinesthetic imagery of a previously known set of finger and arm movements with simultaneous 30-channel EEG acquisition. The first and the last session mostly consisted of feedback trials in which the subjects were presented with the classification results of the EEG patterns in real time; during the other sessions, no feedback was provided. Spatiotemporal and amplitude features of the ERD patterns concomitant with imagery were compared across experimental days and between feedback conditions using linear mixed-effects modeling.
The main spatial sources of ERD appeared to be highly stable across the six experimental days, remaining nearly identical in five of seven subjects (Pearson's ρ > 0.94). Only in one subject did the spatial pattern of activation statistically significantly differ ( = 0.009) between the feedback and no-feedback conditions. Real-time visual feedback delivered through the BCI did not significantly increase the ERD strength.
The results imply that the potential benefits of MI could be yielded by well-habituated subjects with a simplified open-loop setup, e.g., through at-home self-practice.
运动想象与实际运动所涉及的许多神经回路相同。因此，运动的心理预演常被用于补充体能训练，并可能有助于中风后的运动神经康复。一种试图捕捉大脑参与想象的方法是，将人类脑电图（EEG）中丘脑皮质感觉运动节律的抑制或事件相关去同步化（ERD）用作标记。利用快速实时处理，有可能让受试者意识到自己的大脑反应，或者——甚至更好的是——通过一种称为脑机接口（BCI）的技术将这些反应转化为行动。然而，与开环训练相比，通过BCI实现的想象是否能促进更强或质的不同的大脑反应仍不清楚。
7名在闭环和开环运动想象方面都有经验的健康志愿者在4.5个月的时间里参加了6次实验，他们对一组先前已知的手指和手臂运动进行动觉想象，同时进行30通道EEG采集。第一次和最后一次实验主要由反馈试验组成，在这些试验中，实时向受试者展示EEG模式的分类结果；在其他实验中，不提供反馈。使用线性混合效应模型，比较了不同实验日以及反馈条件之间与想象相关的ERD模式的时空和幅度特征。
在六个实验日中，ERD的主要空间来源似乎高度稳定，在七名受试者中的五名中几乎保持不变（Pearson相关系数ρ>0.94）。只有一名受试者的激活空间模式在反馈和无反馈条件之间存在统计学显著差异（P = 0.009）。通过BCI提供的实时视觉反馈并没有显著增加ERD强度。
结果表明，对于训练有素的受试者，采用简化的开环设置，例如通过在家自行练习，可能会产生运动想象的潜在益处。
