# The role of dopamine-sensitive motor cortical circuits in the development and execution of skilled forelimb movements

## TL;DR

This study explores how dopamine and brain circuits in the motor cortex help mice learn and perform skilled movements to get rewards.

## Contribution

The study reveals how dopamine dynamics and neuronal activity in the motor cortex are linked to skilled movement execution and reward processing.

## Key findings

- Dopamine activity in the motor cortex is temporally linked to movement and reward consumption.
- Neuronal activity in the motor cortex reflects the vigor of forelimb movements.
- D1+ and D2+ neurons are differently distributed in the layers of the motor cortex.

## Abstract

Dopamine (DA) signaling in the primary motor cortex (M1) is crucial for motor skill learning. However, the DA dynamics in the M1 during the formation and execution of skilled behavior have not yet been investigated. We trained head-fixed D1Cre and D2Cre mice to perform skilled forelimb movements with a joystick to collect water rewards and used fiber photometry to simultaneously monitor DA dynamics and population-level calcium (Ca2+) activity from D1+ and D2+ neurons in the M1 forelimb area. We found that the activity of DA and neuronal populations in M1 is temporally linked to joystick movements and reward consumption, tracks actual reward availability, and reflects the vigor of forelimb movement. Our findings show how DA dynamics and activity of local dopaminoceptive circuits in the M1 are shaped during motor learning and execution of skilled behavior.

•Mice perform skilled forelimb movements with a joystick to obtain a delayed water reward•DA dynamics in the M1 encode the execution of forelimb movement and reward consumption•Neural response in the M1 reflects movement vigor•D1+ and D2+ neurons are differently distributed in the layers of M1

Mice perform skilled forelimb movements with a joystick to obtain a delayed water reward

DA dynamics in the M1 encode the execution of forelimb movement and reward consumption

Neural response in the M1 reflects movement vigor

D1+ and D2+ neurons are differently distributed in the layers of M1

Biological sciences; natural sciences; neuroscience; systems neuroscience