Spinal Shox2 interneuron interconnectivity related to function and development

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Abstract

Neuronal networks generating hindlimb locomotion are located in the spinal cord. The mechanisms underlying spinal rhythmogenesis are unknown but network activity and interconnectivity of excitatory interneurons likely play prominent roles. Here, we investigate interconnectivity within the Shox2 interneuron population, a subset of which has been shown to be involved in locomotor rhythm generation, using paired recordings in isolated spinal cords or slices from transgenic mice. Sparse unidirectional connections consistent with chemical synaptic transmission and prominent bidirectional connections mediated by electrical synapses were present within distinct subsets of Shox2 interneurons. Moreover, bidirectional electrical connections were preferentially found between functionally-related Shox2 interneurons. Though prevalent in neonatal mice, electrical coupling began to decline in incidence and strength in mice ~3 weeks of age. Overall, our data suggest that gap junctional coupling promotes synchronization of Shox2 interneurons, and may be implicated in locomotor rhythmicity in developing mice.

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All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 2Eii, 2Fii, 3C, 3F, 4B, 4D, 5B, 5C, 7C and 7D.

Article and author information

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Ngoc T Ha

Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, United States

Competing interests
The authors declare that no competing interests exist.
Kimberly J Dougherty

Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, United States

For correspondence
kjd86@drexel.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-0807-574X

Funding

National Institutes of Health (R01 NS095366)

Kimberly J Dougherty

Wings for Life (WFL-US-003/15)

Kimberly J Dougherty

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

Ethics

Animal experimentation: All experimental procedures followed NIH guidelines and were approved by the Institutional AnimalCare and Use Committee at Drexel University (protocols 20317 and 20657).

Copyright

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.