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

Dopamine signalling in the motor cortex is crucial for motor skill learning. Here we resolve the spatiotemporal dopamine dynamics and the activity of local dopaminoceptive circuits during the formation and execution of motor skills. We trained head-fixed mice to perform skilled forelimb movements with a joystick to collect water rewards, while simultaneously monitoring dopamine release and calcium dynamics in the forelimb area of motor cortex. We found that dopamine release events and calcium transients were temporally linked to joystick movements and reward consumption. Dopamine dynamics and population level activity of dopamine-receptive neurons scaled with the vigor of forelimb movements and tracked the relationship between actions and their consequences. Optogenetic photoinhibition of cortical dopaminoceptive circuits reduced the number of rewarded joystick movements. Our findings show how phasic dopamine signals in the motor cortex facilitate reinforcement motor learning of skilled behavior.