Dopamine signaling in the medial accumbens shell constrains the duration of reinforced actions.

Dopamine regulates the frequency of motor actions, but it is unclear whether it similarly regulates the duration of discrete behaviors. Here, we show that dopamine signaling within the medial accumbens shell reinforces actions while simultaneously constraining their duration. When mice hold down a lever to continuously self-stimulate dopamine axons in the medial accumbens shell, hold-downs are rarely longer than 5 s, and higher stimulation frequencies elicit shorter, but more numerous, lever hold-downs. This disengaging property of medial accumbens shell dopamine also applies to consummatory behavior, as mice are quicker to both terminate and reinitiate bouts of licking paired with high-frequency dopamine axon stimulation. Dopamine D1 receptors underpin this disengaging property of dopamine signaling, as we demonstrate a D1 agonist shortens both self-stimulation hold-downs and bouts of consummatory behavior. Altogether, we uncover an anatomically defined role of dopamine, which is to disengage its own reinforcing properties through D1 receptor signaling.