title: Oligosynaptic inhibition of group Ia afferents from brachioradialis to triceps brachii motor neurons in humans.
abstract: BACKGROUND
  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.
  
  
  CONCLUSIONS
  These findings suggest that oligosynaptic inhibition mediated by group Ia afferents from BR to TB exists in humans. Muscle Nerve 57: 122-128, 2018.
authors.affiliation: Department of Occupational Therapy, Yamagata Prefectural University of Health Sciences, Yamagata, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Anatomy and Structural Science, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata, 990-9585, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Nito
authors.affiliation: Department of Physical Therapy, Yamagata Prefectural University of Health Sciences, Yamagata, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Department of Occupational Therapy, Yamagata Prefectural University of Health Sciences, Yamagata, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Fujii
authors.affiliation: Department of Anatomy and Structural Science, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata, 990-9585, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Hashizume
authors.affiliation: Department of Judo Therapy, Teikyo University Faculty of Medical Technology, Utsunomiya, Japan.
authors.forename: Takuji
authors.initials: T
authors.lastname: Miyasaka
authors.affiliation: Graduate School of Health Sciences, Matsumoto University, Matsumoto, Japan.
authors.forename: Masaomi
authors.initials: M
authors.lastname: Shindo
authors.affiliation: Department of Anatomy and Structural Science, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata, 990-9585, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Naito
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D055815:Young Adult
keywords: brachioradialis; group Ia afferents; humans; oligosynaptic inhibition; triceps brachii