title: Effects of movement-related afferent inputs on spinal reflexes evoked by transcutaneous spinal cord stimulation during robot-assisted passive stepping.
abstract: Studies of robot-assisted passive stepping paradigms have reported that movement-related afferent inputs strongly inhibit the excitability of the Hoffmann (H) reflex in the soleus (Sol) during walking. However, it is unknown if movement-related afferent inputs have the same effect on the excitability of spinal reflexes in the other lower-limb muscles that are involved in normal walking in healthy subjects. The aim of this study was to examine the effects of movement-related afferent inputs on the spinal reflexes in lower-limb muscles during walking. Spinal reflexes that were elicited by transcutaneous spinal cord stimulation (tSCS) were recorded during passive air standing and air stepping at three stepping velocities (stride frequencies: 14, 25, and 36 strides/min). The amplitude of the spinal reflexes was reduced in most of the recorded muscles during passive air stepping compared with air standing. Furthermore, in the Sol and lateral gastrocnemius, the amplitude of the reflexes during air stepping significantly decreased as stride frequency increased. These results demonstrate that movement-related afferent inputs inhibit spinal reflexes in the Sol and other lower-limb muscles during walking.
authors.affiliation: Department of Rehabilitation for Movement Functions, Research Institute of the National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan. Electronic address: masugi-yohei@rehab.go.jp.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Masugi
authors.affiliation: Department of Rehabilitation for Movement Functions, Research Institute of the National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Kawashima
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Inoue
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Nakazawa
mesh_terms: D000328:Adult; D004576:Electromyography; D005260:Female; D006181:H-Reflex; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D012371:Robotics; D013116:Spinal Cord / Q000502:physiology*; D062187:Spinal Cord Stimulation; D004561:Transcutaneous Electric Nerve Stimulation; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Afferent input; Locomotion; Passive stepping; Spinal reflex; Transcutaneous spinal cord stimulation