Masugi Yohei, Kitamura Taku, Kamibayashi Kiyotaka, Ogawa Tetsuya, Ogata Toru, Kawashima Noritaka, Nakazawa Kimitaka
Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
Division of Functional Control Systems, Graduate School of Engineering and Science, Shibaura Institute of Technology, 307, Fukasaku, Minuma-ku, Saitama-shi, Saitama 337-8570, Japan; Department of Motor Dysfunction, Research Institute of National Rehabilitation Center for the Disabled, 4-1 Namiki, Tokorozawa-shi, Saitama 359-8555, Japan.
Neurosci Lett. 2015 Jan 1;584:337-41. doi: 10.1016/j.neulet.2014.10.044. Epub 2014 Nov 3.
The amplitude of the Hoffmann (H)-reflex in the soleus (Sol) muscle is known to be suppressed during passive stepping compared with during passive standing. The reduction of the H-reflex is not due to load-related afferent inputs, but rather to movement-related afferent inputs from the lower limbs. To elucidate the underlying neural mechanisms of this inhibition, we investigated the effects of the stepping velocity on the Sol H-reflex during robot-assisted passive stepping in 11 healthy subjects. The Sol H-reflexes were recorded during passive standing and stepping at five stepping velocities (stride frequencies: 14, 21, 28, 35, and 42 min(-1)) in the air. The Sol H-reflexes were significantly inhibited during passive stepping as compared with during passive standing, and reduced in size as the stepping velocity increased. These results indicate that the extent of H-reflex suppression increases with increasing movement-related afferent inputs from the lower limbs during passive stepping. The velocity dependence suggests that the Ia afferent inputs from lower-limb muscles around the hip and knee joints are most probably related to this inhibition.
与被动站立相比，比目鱼肌（Sol）的霍夫曼（H）反射波幅在被动踏步时会受到抑制。H反射的降低并非源于与负荷相关的传入输入，而是来自下肢与运动相关的传入输入。为了阐明这种抑制作用的潜在神经机制，我们在11名健康受试者进行机器人辅助被动踏步期间，研究了踏步速度对Sol H反射的影响。在空气中，于被动站立以及五种踏步速度（步频：14、21、28、35和42次/分钟）的被动踏步过程中记录Sol H反射。与被动站立相比，被动踏步期间Sol H反射受到显著抑制，并且随着踏步速度增加，其波幅减小。这些结果表明，在被动踏步期间，随着来自下肢与运动相关的传入输入增加，H反射抑制的程度也会增加。速度依赖性表明，来自髋关节和膝关节周围下肢肌肉的Ia传入输入很可能与这种抑制作用有关。
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