# Anatomical and functional characterization of the role of projection-specific populations of corticospinal neurons in motor control

> **NIH NIH U19** · COLUMBIA UNIVERSITY HEALTH SCIENCES · 2020 · $409,696

## Abstract

Abstract
Motor cortex (M1) plays a crucial role in the control of voluntary movement but the neuronal mechanisms by
which this region converges on downstream circuits remain obscure. To better understand how activity in M1 is
translated into context-appropriate behaviors, we propose to characterize the role of specific cortical projection
subtypes as defined by their spinal interneuron targets. A growing body of electrophysiological and behavioral
evidence suggests that interneuron subsets in the spinal cord represent functional units that, when recruited,
play a role in imposing a task-appropriate pattern of muscle activation. An example of this is seen in the
alternating activity of opposing flexor and extensor muscles, which is in part regulated by defined spinal circuits.
These circuits can be over-ridden to achieve simultaneous antagonist muscle coactivation. Two inhibitory spinal
interneuron (IN) populations, presynaptic GABAergic (GABApre) and reciprocal inhibitory GABA/glycineric (Ia)
neurons, play a role in this transition, undergoing activation or suppression of their activity, respectively. Using
a recently developed CVS-N2C based rabies tracing strategy combined with genetic access to specific cardinal
interneuron populations, we have identified that both classes receive direct corticospinal neuron (CSN) inputs.
Moreover, this input has been suggested to play a role in the task-appropriate switching from alternating
activation to co-activation of flexor-extensor muscle pairs. In order to investigate the nature of this role, we have
developed a motor behavioral task in, which mice are trained to either alternate or co-contract opposing forelimb
muscles in response to a visual cue. For the first time, we can now simultaneously monitor and manipulate the
activity of defined subsets of CSNs during a motor-cortically dependent behavior.

## Key facts

- **NIH application ID:** 9983206
- **Project number:** 5U19NS104649-04
- **Recipient organization:** COLUMBIA UNIVERSITY HEALTH SCIENCES
- **Principal Investigator:** Thomas M. Jessell
- **Activity code:** U19 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $409,696
- **Award type:** 5
- **Project period:** 2017-09-25 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9983206

## Citation

> US National Institutes of Health, RePORTER application 9983206, Anatomical and functional characterization of the role of projection-specific populations of corticospinal neurons in motor control (5U19NS104649-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9983206. Licensed CC0.

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