Kawai Kazutake, Tazoe Toshiki, Yanai Toshimasa, Kanosue Kazuyuki, Nishimura Yukio
College of Sports Sciences, Nihon University, Tokyo, Japan.
Neural Prosthetics Project, Department of Brain and Neuroscience, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
Front Hum Neurosci. 2022 Sep 23;16:1016064. doi: 10.3389/fnhum.2022.1016064. eCollection 2022.
Transvertebral magnetic stimulation (TVMS) of the human lumbar spinal cord can evoke bilateral rhythmic leg movements, as in walking, supposedly through the activation of spinal locomotor neural circuitry. However, an appropriate stimulus intensity that can effectively drive the human spinal locomotor circuitry to evoke walking-like movements has not been determined. To address this issue, TVMS was delivered over an intervertebral space of the lumbar cord (L1-L3) at different stimulus intensities (10-70% of maximum stimulator output) in healthy human adults. In a stimulus intensity-dependent manner, TVMS evoked two major patterns of rhythmic leg movements in which the left-right movement cycles were coordinated with different phase relationships: hopping-like movements, in which both legs moved in the same direction in phase, and walking-like movements, in which both legs moved alternatively in anti-phase; uncategorized movements were also observed which could not be categorized as either movement type. Even at the same stimulation site, the stimulus-evoked rhythmic movements changed from hopping-like movements to walking-like movements as stimulus intensity was increased. Different leg muscle activation patterns were engaged in the induction of the hopping- and walking-like movements. The magnitude of the evoked hopping- and walking-like movements was positively correlated with stimulus intensity. The human spinal neural circuitry required a higher intensity of magnetic stimulation to produce walking-like leg movements than to produce hopping-like movements. These results suggest that TVMS activates distinct neural modules in the human spinal cord to generate hopping- and walking-like movements.
对人类腰脊髓进行经椎骨磁刺激（TVMS）可以诱发双侧有节奏的腿部运动，就像行走时一样，据推测是通过激活脊髓运动神经回路实现的。然而，尚未确定能够有效驱动人类脊髓运动回路以诱发类似行走运动的合适刺激强度。为了解决这个问题，在健康成年人中，以不同的刺激强度（最大刺激器输出的10%-70%）在腰脊髓的椎间间隙（L1-L3）进行TVMS。TVMS以刺激强度依赖的方式诱发了两种主要的有节奏腿部运动模式，其中左右运动周期以不同的相位关系协调：类似跳跃的运动，即双腿同相朝同一方向运动；类似行走的运动，即双腿反相交替运动；还观察到无法归类为这两种运动类型的未分类运动。即使在相同的刺激部位，随着刺激强度增加，刺激诱发的有节奏运动也会从类似跳跃的运动转变为类似行走的运动。在诱发类似跳跃和类似行走的运动过程中，腿部肌肉的激活模式不同。诱发的类似跳跃和类似行走运动的幅度与刺激强度呈正相关。与产生类似跳跃的运动相比，人类脊髓神经回路需要更高强度的磁刺激来产生类似行走的腿部运动。这些结果表明，TVMS激活人类脊髓中不同的神经模块以产生类似跳跃和类似行走的运动。
