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

Dopamine signaling in the medial accumbens shell constrains discrete action duration: lever hold-downs are rarely longer than 5 s and higher stimulation frequencies shorten them.

• Why it matters: Dopamine is known to regulate motor action frequency, but whether it also regulates the duration of discrete behaviors was unclear.
• What they did: In mice, medial accumbens shell dopamine axon self-stimulation showed hold-downs rarely exceeding 5 s, with higher frequencies producing shorter, more numerous bouts; D1 agonist effects were tested on lever and licking.
• The result: High-frequency stimulation also made mice terminate and reinitiate licking bouts faster, and D1 receptor signaling underpinned this disengaging property by shortening both self-stimulation hold-downs and consummatory bouts.