title: Soleus Hoffmann reflex amplitudes are specifically modulated by cutaneous inputs from the arms and opposite leg during walking but not standing.
abstract: Electrical stimulation of cutaneous nerves innervating heteronymous limbs (the arms or contralateral leg) modifies the excitability of soleus Hoffmann (H-) reflexes. The differences in the sensitivities of the H-reflex pathway to cutaneous afferents from different limbs and their modulation during the performance of motor tasks (i.e., standing and walking) are not fully understood. In the present study, we investigated changes in soleus H-reflex amplitudes induced by electrical stimulation of peripheral nerves. Selected targets for conditioning stimulation included the superficial peroneal nerve, which innervates the foot dorsum in the contralateral ankle (cSP), and the superficial radial nerve, which innervates the dorsum of the hand in the ipsilateral (iSR) or contralateral wrist (cSR). Stimulation and subsequent reflex assessment took place during the standing and early-stance phase of treadmill walking in ten healthy subjects. Cutaneous stimulation produced long-latency inhibition (conditioning-test interval of ~100 ms) of the H-reflex during the early-stance phase of walking, and the inhibition was stronger following cSP stimulation compared with iSR or cSR stimulation. In contrast, although similar conditioning stimulation significantly facilitated the H-reflex during standing, this effect remained constant irrespective of the different conditioning sites. These findings suggest that cutaneous inputs from the arms and contralateral leg had reversible effects on the H-reflex amplitudes, including inhibitions with different sensitivities during the early-stance phase of walking and facilitation during standing. Furthermore, the differential sensitivities of the H-reflex modulations were expressed only during walking when the locations of the afferent inputs were functionally relevant.
authors.affiliation: Division of Health and Sports Education, The United Graduate School of Education, Tokyo Gakugei University, Tokyo, Japan. ssuzukiphysiol1@ks.kyorin-u.ac.jp.|Department of Integrative Physiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, 181-8611, Japan. ssuzukiphysiol1@ks.kyorin-u.ac.jp.
authors.forename: Shinya
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Department of Integrative Physiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, 181-8611, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Nakajima
authors.affiliation: Division of Health and Sports Education, The United Graduate School of Education, Tokyo Gakugei University, Tokyo, Japan.|Faculty of Business and Information Sciences, Jobu University, Isesaki, Gunma, Japan.
authors.forename: Genki
authors.initials: G
authors.lastname: Futatsubashi
authors.affiliation: Laboratory of Signal Processing and Motor Control, College of Physical Education, University of Brasília, Brasília, Brazil.|Biomedical Engineering Laboratory, EPUSP, PTC, University of São Paulo, São Paulo, Brazil.|Division of Health and Sports Sciences, Faculty of Education, Chiba University, Chiba, Japan.
authors.forename: Rinaldo A
authors.initials: RA
authors.lastname: Mezzarane
authors.affiliation: Department of Physical Therapy, School of Rehabilitation Sciences, Health Sciences University of Hokkaido, Hokkaido, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohtsuka
authors.affiliation: Department of Integrative Physiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, 181-8611, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Ohki
authors.affiliation: Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC, Canada.|Centre for Biomedical Research, University of Victoria, Victoria, BC, Canada.|International Collaboration on Repair Discoveries (ICORD), Vancouver, BC, Canada.
authors.forename: E Paul
authors.initials: EP
authors.lastname: Zehr
authors.affiliation: Division of Health and Sports Education, The United Graduate School of Education, Tokyo Gakugei University, Tokyo, Japan.|Division of Health and Sports Sciences, Faculty of Education, Chiba University, Chiba, Japan.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Komiyama
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D005121:Extremities / Q000502:physiology*; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D009433:Neural Inhibition / Q000502:physiology*; D010543:Peroneal Nerve / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011826:Radial Nerve / Q000502:physiology*; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Cutaneous afferents; H-reflex; Interlimb coordination; Locomotion; Presynaptic inhibition