Oligosynaptic inhibition of group Ia afferents from brachioradialis to triceps brachii motor neurons in humans |
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| Authors: | Toshiaki Sato PhD Mitsuhiro Nito PhD Katsuhiko Suzuki PhD Hiromi Fujii PhD Wataru Hashizume Takuji Miyasaka PhD Masaomi Shindo MD PhD Akira Naito MD PhD |
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| Affiliation: | 1. Department of Occupational Therapy, Yamagata Prefectural University of Health Sciences, Yamagata, Japan;2. Department of Anatomy and Structural Science, Yamagata University School of Medicine, 2‐2‐2 Iida‐nishi, Yamagata, Japan;3. Department of Physical Therapy, Yamagata Prefectural University of Health Sciences, Yamagata, Japan;4. Department of Judo Therapy, Teikyo University Faculty of Medical Technology, Utsunomiya, Japan;5. Graduate School of Health Sciences, Matsumoto University, Matsumoto, Japan |
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| Abstract: | Introduction: This study examines effects of low‐threshold afferents from the brachioradialis (BR) on excitability of triceps brachii (TB) motor neurons in humans. Methods: We evaluated the effects using a post stimulus time histogram (PSTH) and electromyogram averaging (EMG‐A) methods in 13 healthy human participants. Electrical conditioning stimulation to the radial nerve branch innervating BR with the intensity below the motor threshold was delivered. Results: In the PSTH study, the stimulation produced a trough (inhibition) in 36/69 TB motor units for all the participants. A cutaneous stimulation never provoked such inhibition. The central latency of the inhibition was 1.5 ± 0.5 ms longer than that of the homonymous facilitation. In the EMG‐A study, the stimulation produced inhibition in EMG‐A of TB in all participants. The inhibition diminished with a tonic vibration stimulation to BR. Discussion: These findings suggest that oligosynaptic inhibition mediated by group Ia afferents from BR to TB exists in humans. Muscle Nerve 57 : 122–128, 2018 |
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| Keywords: | brachioradialis group Ia afferents humans oligosynaptic inhibition triceps brachii |
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