Division of Functional and Restorative Neurosurgery, Tuebingen NeuroCampus, Eberhard Karls University Tuebingen, Tuebingen, Germany.
Division of Functional and Restorative Neurosurgery, Tuebingen NeuroCampus, Eberhard Karls University Tuebingen, Tuebingen, Germany.
Brain Stimul. 2019 Jul-Aug;12(4):1027-1040. doi: 10.1016/j.brs.2019.03.009. Epub 2019 Mar 12.
Motor imagery (MI) engages cortical areas in the human brain similar to motor practice. Corticospinal excitability (CSE) is facilitated during but not after MI practice. We hypothesized that lasting CSE changes could be achieved by associatively pairing this endogenous modulation with exogenous stimulation of the same intracortical circuits.
We combined MI with a disinhibition protocol (DIS) targeting intracortical circuits by paired-pulse repetitive transcranial magnetic stimulation in one main and three subsequent experiments. The follow-up experiments were applied to increase effects, e.g., by individualizing inter-stimulus intervals, adding neuromuscular stimulation and expanding the intervention period. CSE was captured during (online) and after (offline) the interventions via input-output changes and cortical maps of motor evoked potentials. A total of 35 healthy subjects (mean age 26.1 ± 2.6 years, 20 females) participated in this study.
A short intervention (48 stimuli within ∼90s) increased CSE. This plasticity developed rapidly, was associative (with MI, but not MI or REST) and persisted beyond the intervention period. Follow-up experiments revealed the relevance of individualizing inter-stimulus intervals and of consistent inter-burst periods for online and offline effects, respectively. Expanding this combined MI/DIS intervention to 480 stimuli amplified the sustainability of CSE changes. When concurrent neuromuscular electrical stimulation was applied, the plasticity induction was cancelled.
This novel associative stimulation protocol augmented plasticity induction in the human motor cortex within a remarkably short period of time and in the absence of active movements. The combination of endogenous and exogenous disinhibition of intracortical circuits may provide a therapeutic backdoor when active movements are no longer possible, e.g., for hand paralysis after stroke.
运动想象（MI）会激活大脑皮质中的运动区域，与运动练习相似。皮质脊髓兴奋性（CSE）在 MI 练习期间得到促进，但在练习后不会得到促进。我们假设，通过将这种内源性调节与相同的皮质内回路的外源性刺激相联系，可以实现持久的 CSE 变化。
我们在一个主要实验和三个后续实验中，通过成对脉冲重复经颅磁刺激（rTMS），将 MI 与针对皮质内回路的去抑制协议（DIS）相结合。后续实验旨在通过个性化刺激间隔、添加神经肌肉刺激和扩大干预期来增加效果。通过输入-输出变化和运动诱发电位的皮质图，在干预期间（在线）和之后（离线）捕获 CSE。共有 35 名健康受试者（平均年龄 26.1±2.6 岁，20 名女性）参与了这项研究。
一个短的干预（在约 90 秒内 48 次刺激）增加了 CSE。这种可塑性发展迅速，是联想性的（与 MI 相关，而不是 MI 或 REST），并在干预期后持续存在。后续实验表明，个性化刺激间隔和一致的爆发间隔对于在线和离线效果分别具有相关性。将这种结合的 MI/DIS 干预扩展到 480 次刺激，增强了 CSE 变化的可持续性。当同时应用神经肌肉电刺激时，可塑性诱导被取消。
这种新的联想性刺激方案在极短的时间内增强了人类运动皮质的可塑性诱导，而且不需要主动运动。内源性和外源性抑制皮质内回路的结合可能为无法进行主动运动时提供一种治疗途径，例如中风后手瘫痪。
