title: Phase-dependent reversal of the crossed conditioning effect on the soleus Hoffmann reflex from cutaneous afferents during walking in humans.
abstract: We previously demonstrated that non-noxious electrical stimulation of the cutaneous nerve innervating the contralateral foot modified the excitability of the Hoffmann (H-) reflex in the soleus muscle (SOL) in a task-dependent manner during standing and walking in humans. To date, however, it remains unclear how the crossed conditioning effect on the SOL H-reflex from the contralateral foot is modified during the various phases of walking. We sought to answer this question in the present study. The SOL H-reflex was evoked in healthy volunteers by an electrical test stimulation (TS) of the right (ipsilateral) posterior tibial nerve at five different phases during treadmill walking (4 km/h). A non-noxious electrical stimulation was delivered to the superficial peroneal nerve of the left (contralateral) ankle ~100 ms before the TS as a conditioning stimulation (CS). This CS significantly suppressed the H-reflex amplitude during the early stance phase, whereas the same CS significantly facilitated the H-reflex amplitude during the late stance phase. The CS alone did not produce detectable changes in the full-wave rectified electromyogram of the SOL. This result indicates that presynaptic mechanisms driven by the activation of low-threshold cutaneous afferents in the contralateral foot play a role in regulating the transmission between the Ia terminal and motoneurons in a phase-dependent manner. The modulation pattern of the crossed conditioning effect on the SOL H-reflex may be functionally relevant for the left-right coordination of leg movements during bipedal walking.
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, 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, 1-33 Yayoicho, Inage-ku, Chiba, 263-8522, 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: Division of Health and Sports Education, The United Graduate School of Education, Tokyo Gakugei University, Tokyo, Japan. komiyama@faculty.chiba-u.jp.|Division of Health and Sports Sciences, Faculty of Education, Chiba University, 1-33 Yayoicho, Inage-ku, Chiba, 263-8522, Japan. komiyama@faculty.chiba-u.jp.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Komiyama
mesh_terms: D000328:Adult; D003213:Conditioning, Psychological / Q000502:physiology*; D004576:Electromyography / Q000379:methods; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Cutaneous inputs; Interlimb coordination; Phase-dependency; Presynaptic inhibition; Walking