Nucleus accumbens dopamine modulates response rate but not response timing in an interval timing task.

While previous work has demonstrated that systemic dopamine manipulations can modulate temporal perception by altering the speed of internal clock processes, the neural site of this modulation remains unclear. Based on recent research suggesting that changes in incentive salience can alter the perception of time, as well as work showing that nucleus accumbens (NAc) shell dopamine (DA) levels modulate the incentive salience of discriminative stimuli that predict instrumental outcomes, we assessed whether microinjections of DA agents into the NAc shell would impact temporal perception. Rats were trained on either a 10-s or 30-s temporal production procedure and received intra-NAc shell microinfusions of sulpiride, amphetamine, and saline. Results showed that NAc DA modulations had no effect on response timing, but intra-NAc shell sulpiride microinfusions significantly decreased response rates relative to saline and amphetamine. Our findings therefore suggest that neither NAc shell DA levels, nor the resultant changes in incentive salience signaled by this structure, impact temporal control.