A size principle for recruitment of Drosophila leg motor neurons
- University of Washington, United States
- Columbia University, United States
Abstract
To move the body, the brain must precisely coordinate patterns of activity among diverse populations of motor neurons. Here, we use in vivo calcium imaging, electrophysiology, and behavior to understand how genetically-identified motor neurons control flexion of the fruit fly tibia. We find that leg motor neurons exhibit a coordinated gradient of anatomical, physiological, and functional properties. Large, fast motor neurons control high force, ballistic movements while small, slow motor neurons control low force, postural movements. Intermediate neurons fall between these two extremes. This hierarchical organization resembles the size principle, first proposed as a mechanism for establishing recruitment order among vertebrate motor neurons. Recordings in behaving flies confirmed that motor neurons are typically recruited in order from slow to fast. However, we also find that fast, intermediate, and slow motor neurons receive distinct proprioceptive feedback signals, suggesting that the size principle is not the only mechanism that dictates motor neuron recruitment. Overall, this work reveals the functional organization of the fly leg motor system and establishes Drosophila as a tractable system for investigating neural mechanisms of limb motor control.
Data availability
All data is publicly available on Dryad doi:10.5061/dryad.76hdr7stb
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Data for: A size principle for recruitment of Drosophila leg motor neuronsDryad Digital Repository, doi:10.5061/dryad.76hdr7stb.
Article and author information
Author details
Lalanti Venkatasubramanian
Funding
NIH (U19NS104655)
- Anthony W Azevedo
- Evyn S Dickinson
- Pralaksha Gurung
- Lalanti Venkatasubramanian
- Richard S Mann
- John C Tuthill
Searle Foundation (Scholar Award)
- Anthony W Azevedo
- Evyn S Dickinson
- Pralaksha Gurung
- John C Tuthill
McKnight Foundation (Scholar Award)
- Anthony W Azevedo
- Evyn S Dickinson
- Pralaksha Gurung
- John C Tuthill
Pew Biomedical Trust (Scholar Award)
- Anthony W Azevedo
- Evyn S Dickinson
- Pralaksha Gurung
- John C Tuthill
Sloan Foundation (Research Fellowship)
- Anthony W Azevedo
- Evyn S Dickinson
- Pralaksha Gurung
- John C Tuthill
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Ronald L Calabrese, Emory University, United States
Version history
- Received: March 9, 2020
- Accepted: June 1, 2020
- Accepted Manuscript published: June 3, 2020 (version 1)
- Version of Record published: July 9, 2020 (version 2)
Copyright
© 2020, Azevedo 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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A size principle for recruitment of Drosophila leg motor neurons
eLife 9:e56754.
https://doi.org/10.7554/eLife.56754
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