Cortex commands the performance of skilled movement
- Janelia Farm Research Campus, Howard Hughes Medical Institute, United States
Abstract
Mammalian cerebral cortex is accepted as being critical for voluntary motor control, but what functions depend on cortex is still unclear. Here we used rapid, reversible optogenetic inhibition to test the role of cortex during a head-fixed task in which mice reach, grab, and eat a food pellet. Sudden cortical inhibition blocked initiation or froze execution of this skilled prehension behavior, but left untrained forelimb movements unaffected. Unexpectedly, kinematically normal prehension occurred immediately after cortical inhibition even during rest periods lacking cue and pellet. This 'rebound' prehension was only evoked in trained and food-deprived animals, suggesting that a motivation-gated motor engram sufficient to evoke prehension is activated at inhibition's end. These results demonstrate the necessity and sufficiency of cortical activity for enacting a learned skill.
Article and author information
Author details
Reviewing Editor
- Michael Hausser, University College London, United Kingdom
Ethics
Animal experimentation: Animal procedures were performed in accordance with protocols (13-99) approved by the Institutional Animal Care and Use Committee (IACUC) of the Janelia Research Campus.
Version history
- Received: August 11, 2015
- Accepted: December 1, 2015
- Accepted Manuscript published: December 2, 2015 (version 1)
- Version of Record published: February 1, 2016 (version 2)
- Version of Record updated: June 16, 2016 (version 3)
- Version of Record updated: October 20, 2016 (version 4)
Copyright
© 2015, Guo 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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Cortex commands the performance of skilled movement
eLife 4:e10774.
https://doi.org/10.7554/eLife.10774
Further reading
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- Neuroscience
Vesicles within presynaptic terminals are thought to be segregated into a variety of readily releasable and reserve pools. The nature of the pools and trafficking between them is not well understood, but pools that are slow to mobilize when synapses are active are often assumed to feed pools that are mobilized more quickly, in a series. However, electrophysiological studies of synaptic transmission have suggested instead a parallel organization where vesicles within slowly and quickly mobilized reserve pools would separately feed independent reluctant- and fast-releasing subdivisions of the readily releasable pool. Here, we use FM-dyes to confirm the existence of multiple reserve pools at hippocampal synapses and a parallel organization that prevents intermixing between the pools, even when stimulation is intense enough to drive exocytosis at the maximum rate. The experiments additionally demonstrate extensive heterogeneity among synapses in the relative sizes of the slowly and quickly mobilized reserve pools, which suggests equivalent heterogeneity in the numbers of reluctant and fast-releasing readily releasable vesicles that may be relevant for understanding information processing and storage.
