Motor actions are spatially organized in motor and dorsal premotor cortex
- University of Pittsburgh, United States
Abstract
Frontal motor areas are central to controlling voluntary movements. In non-human primates, the motor areas contain independent, somatotopic, representations of the forelimb (i.e., motor maps). But are the neural codes for actions spatially organized within those forelimb representations? Addressing this question would provide insight into the poorly understood structure-function relationships of the cortical motor system. Here, we tackle the problem using high resolution optical imaging and motor mapping in motor (M1) and dorsal premotor (PMd) cortex. Two macaque monkeys performed an instructed reach-to-grasp task while cortical activity was recorded with intrinsic signal optical imaging (ISOI). The spatial extent of activity in M1 and PMd was then quantified in relation to the forelimb motor maps, which we obtained from the same hemisphere with intracortical microstimulation. ISOI showed that task-related activity was concentrated in patches that collectively overlapped <40% of the M1 and PMd forelimb representations. The spatial organization of the patches was consistent across task conditions despite small variations in forelimb use. Nevertheless, the largest condition differences in forelimb use were reflected in the magnitude of cortical activity. Distinct time course profiles from patches in arm zones and patches in hand zones suggest functional differences within the forelimb representations. The results collectively support an organizational framework wherein the forelimb representations contain subzones enriched with neurons tuned for specific actions. Thus, the often-overlooked spatial dimension of neural activity appears to be an important organizing feature of the neural code in frontal motor areas.
Data availability
All data and code used in this paper is posted on OSF.DOI: 10.17605/OSF.IO/7SGBEhttps://osf.io/7sgbe/
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Motor actions are spatially organized in motor and dorsal premotor cortexDOI: 10.17605/OSF.IO/7SGBE.
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Author details
Funding
National Institutes of Health (R01 NS105697)
- Omar A Gharbawie
Whitehall Foundation (2017-12-94)
- Omar A Gharbawie
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 procedures were approved by the University of Pittsburgh Animal Care and Use Committees (protocol #21049001) and followed the guidelines of the National Institutes of Health guide for the care and use of laboratory animals.
Copyright
© 2023, Chehade & Gharbawie
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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Motor actions are spatially organized in motor and dorsal premotor cortex
eLife 12:e83196.
https://doi.org/10.7554/eLife.83196
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