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

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 (Ca(2+)) 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.