Spinal V2b neurons reveal a role for ipsilateral inhibition in speed control
- Washington University School of Medicine, United States
- National Institute for Basic Biology, Japan
Abstract
The spinal cord contains a diverse array of interneurons that govern motor output. Traditionally, models of spinal circuits have emphasized the role of inhibition in enforcing reciprocal alternation between left and right sides or flexors and extensors. However, recent work has shown that inhibition also increases coincident with excitation during contraction. Here, using larval zebrafish, we investigate the V2b (Gata3+) class of neurons, which contribute to flexor-extensor alternation but are otherwise poorly understood. Using newly generated transgenic lines we define two stable subclasses with distinct neurotransmitter and morphological properties. These V2b subclasses synapse directly onto motor neurons with differential targeting to speed-specific circuits. In vivo, optogenetic manipulation of V2b activity modulates locomotor frequency: suppressing V2b neurons elicits faster locomotion, whereas activating V2b neurons slows locomotion. We conclude that V2b neurons serve as a brake on axial motor circuits. Together, these results indicate a role for ipsilateral inhibition in speed control.
Data availability
Datasets have been deposited on Dryad, https://dx.doi.org/10.5061/dryad.1d78mt2
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Data from: Spinal V2b neurons reveal a role for ipsilateral inhibition in speed controlDryad, doi:10.5061/dryad.1d78mt2.
Article and author information
Author details
Funding
National BioResource Project
- Shin-ichi Higashijima
National Institute on Deafness and Other Communication Disorders (R00 DC012536)
- Martha W Bagnall
National Institute on Deafness and Other Communication Disorders (R01 DC016413)
- Martha W Bagnall
National Institute of Neurological Disorders and Stroke (F32 NS103247)
- Rebecca A Callahan
Alfred P. Sloan Foundation
- Martha W Bagnall
Pew Charitable Trusts
- Martha W Bagnall
McKnight Endowment Fund for Neuroscience
- Martha W Bagnall
Children's Discovery Institute
- Martha W Bagnall
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: This research adheres to recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health and received approval by the Washington University Institutional Animal Care and Use Committee (protocol 20170228).
Copyright
© 2019, Callahan 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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Spinal V2b neurons reveal a role for ipsilateral inhibition in speed control
eLife 8:e47837.
https://doi.org/10.7554/eLife.47837
