Refy Omar, Blanchard Belle, Miller-Peterson Abigail, Dalrymple Ashley N, Bedoy Ernesto H, Zaripova Amelia, Motaghedi Nadim, Mo Owen, Panthangi Shalini, Reinhart Alex, Torres-Oviedo Gelsy, Geyer Hartmut, Weber Douglas J
Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States.
NeuroMechatronics Lab, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States.
J Neurophysiol. 2023 Oct 1;130(4):1008-1014. doi: 10.1152/jn.00248.2023. Epub 2023 Sep 13.
The dynamics and interaction of spinal and supraspinal centers during locomotor adaptation remain vaguely understood. In this work, we use Hoffmann reflex measurements to investigate changes in spinal reflex gains during split-belt locomotor adaptation. We show that spinal reflex gains are dynamically modulated during split-belt locomotor adaptation. During first exposure to split-belt transitions, modulation occurs mostly on the leg ipsilateral to the speed change and constitutes rapid suppression or facilitation of the reflex gains, followed by slow recovery to baseline. Over repeated exposure, the modulation pattern washes out. We further show that reflex gain modulation strongly correlates with correction of leg asymmetry, and cannot be explained by speed modulation solely. We argue that reflex modulation is likely of supraspinal origins and constitutes an integral part of the neural substrate underlying split-belt locomotor adaptation. This work presents direct evidence for spinal reflex modulation during locomotor adaptation. In particular, we show that reflexes can be modulated on-demand unilaterally during split-belt locomotor adaptation and speculate about reflex modulation as an underlying mechanism for adaptation of gait asymmetry in healthy adults.
在运动适应过程中，脊髓和脊髓上中枢的动态变化及相互作用仍未得到清晰的理解。在这项研究中，我们利用霍夫曼反射测量来研究分带运动适应过程中脊髓反射增益的变化。我们发现，在分带运动适应过程中，脊髓反射增益会动态调节。在首次接触分带转换时，调节主要发生在与速度变化同侧的腿部，表现为反射增益的快速抑制或易化，随后缓慢恢复至基线水平。经过反复接触，调节模式消失。我们进一步表明，反射增益调节与腿部不对称的校正密切相关，不能仅用速度调节来解释。我们认为，反射调节可能起源于脊髓上中枢，是分带运动适应潜在神经基质的一个组成部分。这项研究为运动适应过程中的脊髓反射调节提供了直接证据。特别是，我们表明在分带运动适应过程中，反射可按需单侧调节，并推测反射调节是健康成年人步态不对称适应的潜在机制。
