Log in

Monosynaptic facilitation mediated by group Ia afferents from deltoid to biceps brachii motoneurons in humans

  • Research Article
  • Published:
Experimental Brain Research Aims and scope Submit manuscript

Abstract

Effects of low-threshold afferents from the anterior (DA), middle (DM) and posterior parts of the deltoid (DP) on the excitability of biceps brachii (BB) motoneurons in humans were studied. We evaluated the effects on individual motor units and motoneuron pool using a post-stimulus time-histogram (PSTH) and an electromyogram-averaging (EMG-A) methods, respectively, in 11 healthy human subjects. Electrical conditioning stimulation was delivered to the axillary nerve branch innervating DA (DA nerve), DM (DM nerve) and DP (DP nerve) with the intensity below the motor threshold. In the PSTH study, stimulation to the DA, DM and DP nerves produced a significant peak (facilitation) in 26/40 (65%), 28/47 (59%) and 0/32 (0%) of BB motor units, respectively. Since the central latency of the facilitation from the DA and DM nerves was 0.1 ± 0.3 and 0.1 ± 0.2 ms (mean ± S.D.) longer than that of the homonymous monosynaptic Ia facilitation of BB, respectively, the facilitation thus being compatible with monosynaptic path. In the EMG-A study, stimulation to the DA and DM nerves produced a significant peak (facilitation) for the BB motoneuron pool in all the subjects, whereas stimulation to the DP nerve produced no effect on BB. The facilitation diminished by vibration stimulation, and the suppression lasted for 30–40 min after removal of the vibration. Therefore, group Ia afferents should be responsible for the facilitation. These findings suggest that monosynaptic facilitation mediated by group Ia afferents from the DA and DM nerves to BB motoneurons exists in humans.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Subscribe and save

Springer+ Basic
EUR 32.99 /Month
  • Get 10 units per month
  • Download Article/Chapter or Ebook
  • 1 Unit = 1 Article or 1 Chapter
  • Cancel anytime
Subscribe now

Buy Now

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5

Similar content being viewed by others

References

Download references

Acknowledgements

The study was supported by Yamagata health support society and JSPS KAKENHI to MN (Grant Number: JP19K19827).

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Mitsuhiro Nito.

Ethics declarations

Conflict of interest

None of the authors have any conflicts of interest to disclosure.

Additional information

Communicated by Francesco Lacquaniti.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary file1 (PDF 311 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Yoshimoto, T., Nito, M., Hashizume, W. et al. Monosynaptic facilitation mediated by group Ia afferents from deltoid to biceps brachii motoneurons in humans. Exp Brain Res 240, 1057–1067 (2022). https://doi.org/10.1007/s00221-022-06332-8

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00221-022-06332-8

Keywords

Navigation