Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.
Institute for Smart Augmentative and Restorative Technologies and Health Innovation (iSMART), University of Alberta, Edmonton, AB, Canada.
J Neuroeng Rehabil. 2024 Jun 18;21(1):103. doi: 10.1186/s12984-024-01395-w.
Humans use their arms in complex ways that often demand two-handed coordination. Neurological conditions limit this impressive feature of the human motor system. Understanding how neuromodulatory techniques may alter neural mechanisms of bimanual coordination is a vital step towards designing efficient rehabilitation interventions. By non-invasively activating the spinal cord, transcutaneous spinal cord stimulation (tSCS) promotes recovery of motor function after spinal cord injury. A multitude of research studies have attempted to capture the underlying neural mechanisms of these effects using a variety of electrophysiological tools, but the influence of tSCS on cortical rhythms recorded via electroencephalography remains poorly understood, especially during bimanual actions. We recruited 12 neurologically intact participants to investigate the effect of cervical tSCS on sensorimotor cortical oscillations. We examined changes in the movement kinematics during the application of tSCS as well as the cortical activation level and interhemispheric connectivity during the execution of unimanual and bimanual arm reaching movements that represent activities of daily life. Behavioral assessment of the movements showed improvement of movement time and error during a bimanual common-goal movement when tSCS was delivered, but no difference was found in the performance of unimanual and bimanual dual-goal movements with the application of tSCS. In the alpha band, spectral power was modulated with tSCS in the direction of synchronization in the primary motor cortex during unimanual and bimanual dual-goal movements and in the somatosensory cortex during unimanual movements. In the beta band, tSCS significantly increased spectral power in the primary motor and somatosensory cortices during the performance of bimanual common-goal and unimanual movements. A significant increase in interhemispheric connectivity in the primary motor cortex in the alpha band was only observed during unimanual tasks in the presence of tSCS. Our observations provide, for the first time, information regarding the supra-spinal effects of tSCS as a neuromodulatory technique applied to the spinal cord during the execution of bi- and unimanual arm movements. They also corroborate the suppressive effect of tSCS at the cortical level reported in previous studies. These findings may guide the design of improved rehabilitation interventions using tSCS for the recovery of upper-limb function in the future.
人类以复杂的方式使用手臂，这通常需要双手协调。神经疾病会限制人类运动系统的这一令人印象深刻的特征。了解神经调节技术如何改变双手协调的神经机制是设计高效康复干预措施的重要步骤。经皮脊髓电刺激（tSCS）通过非侵入性地激活脊髓，促进脊髓损伤后的运动功能恢复。大量研究试图使用各种电生理工具来捕捉这些影响的潜在神经机制，但 tSCS 对通过脑电图记录的皮质节律的影响仍知之甚少，特别是在双手动作期间。我们招募了 12 名神经完整的参与者来研究颈 tSCS 对感觉运动皮质振荡的影响。我们检查了在应用 tSCS 期间运动运动学的变化，以及在执行代表日常生活活动的单手和双手手臂伸展运动期间皮质激活水平和半球间连接的变化。对运动的行为评估表明，当 tSCS 施加时，双手共同目标运动的运动时间和误差得到改善，但在应用 tSCS 时，单手和双手双目标运动的表现没有差异。在 alpha 波段，在执行单手和双手双目标运动时，初级运动皮层的同步方向调制了 tSCS 的光谱功率，在执行单手运动时调制了体感皮层的光谱功率。在 beta 波段，tSCS 在执行双手共同目标和单手运动期间显著增加了初级运动和体感皮层的光谱功率。仅在存在 tSCS 的情况下，在执行单手任务时，初级运动皮层的 alpha 波段的半球间连接显著增加。我们的观察结果首次提供了有关 tSCS 作为一种神经调节技术应用于脊髓时对双和单手手臂运动执行的脊髓上效应的信息。它们还证实了以前研究中报道的 tSCS 在皮质水平的抑制作用。这些发现可能为未来使用 tSCS 恢复上肢功能的改进康复干预措施的设计提供指导。
