Computational modeling of spinal circuits controlling limb coordination and gaits in quadrupeds

  1. Simon M Danner  Is a corresponding author
  2. Natalia A Shevtsova
  3. Alain Frigon
  4. Ilya A Rybak
  1. Drexel University College of Medicine, United States
  2. Université de Sherbrooke, Canada

Abstract

Interactions between cervical and lumbar spinal circuits are mediated by long propriospinal neurons (LPNs). Ablation of descending LPNs in mice disturbs left-right coordination at high speeds without affecting fore-hind alternation. We developed a computational model of spinal circuits consisting of four rhythm generators coupled by commissural interneurons (CINs), providing left-right interactions, and LPNs, mediating homolateral and diagonal interactions. The proposed CIN and diagonal LPN connections contribute to speed-dependent gait transition from walk, to trot, and then to gallop and bound; the homolateral LPN connections ensure fore-hind alternation in all gaits. The model reproduces speed-dependent gait expression in intact and genetically transformed mice and the disruption of hindlimb coordination following ablation of descending LPNs. Inputs to CINs and LPNs can affect interlimb coordination and change gait independent of speed. We suggest that these interneurons represent the main targets for supraspinal and sensory afferent signals adjusting gait.

Article and author information

Author details

  1. Simon M Danner

    Department for Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, United States
    For correspondence
    simon.danner@gmail.com
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4642-7064
  2. Natalia A Shevtsova

    Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Alain Frigon

    Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke, Canada
    Competing interests
    The authors declare that no competing interests exist.
  4. Ilya A Rybak

    Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3461-349X

Funding

National Institutes of Health (R01 NS081713)

  • Ilya A Rybak

National Institutes of Health (R01 NS090919)

  • Ilya A Rybak

National Institutes of Health (R01 NS095366)

  • Natalia A Shevtsova

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Ronald L Calabrese, Emory University, United States

Publication history

  1. Received: August 5, 2017
  2. Accepted: November 21, 2017
  3. Accepted Manuscript published: November 22, 2017 (version 1)
  4. Version of Record published: December 12, 2017 (version 2)

Copyright

© 2017, Danner et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Simon M Danner
  2. Natalia A Shevtsova
  3. Alain Frigon
  4. Ilya A Rybak
(2017)
Computational modeling of spinal circuits controlling limb coordination and gaits in quadrupeds
eLife 6:e31050.
https://doi.org/10.7554/eLife.31050

Further reading

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    A series of recent studies identified key structures in the mesencephalic locomotor region and the caudal brainstem of mice involved in the initiation and control of slow (exploratory) and fast (escape-type) locomotion and gait. However, the interactions of these brainstem centers with each other and with the spinal locomotor circuits are poorly understood. Previously we suggested that commissural and long propriospinal interneurons are the main targets for brainstem inputs adjusting gait (Danner et al., 2017). Here, by extending our previous model, we propose a connectome of the brainstem-spinal circuitry and suggest a mechanistic explanation of the operation of brainstem structures and their roles in controlling speed and gait. We suggest that brainstem control of locomotion is mediated by two pathways, one controlling locomotor speed via connections to rhythm generating circuits in the spinal cord and the other providing gait control by targeting commissural and long propriospinal interneurons.

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