Dopamine Dynamics in the Nucleus Accumbens Reflect Confidence in Detecting the Occurrence and Non-Occurrence of Visual Signals in Perceptual Decision-Making

Dopamine (DA) is critically involved in processes such as reward anticipation, attention, and decision-making. The present study examined the temporal dynamics of phasic DA transients in the nucleus accumbens core (NAcC) during a visual decisional task based on signal detection theory, using the fluorescent DA sensor dLight1.3b. During the decision-making phase, DA transients in the NAcC encoded real-time outcome expectancy, apparently reflecting the confidence of male rats in their choices. Reward prediction errors (RPEs) emerged following reward delivery and omission and were amplified under conditions of increased uncertainty, produced either by degrading the visual target or introducing interfering distraction. Moreover, DA transients were elicited on both visual signal and no-signal trials. These findings demonstrate that DA fluctuations in the NAcC reflect the RPE that incorporates confidence and levels of uncertainty, emphasizing an involvement of nucleus accumbens DA in adaptive decision-making.<b>Significance Statement</b> This study reveals a novel involvement of the widely studied neurotransmitter dopamine in coding the confidence of choice responses in well-established visual decision-making in the rat. Reward prediction errors were shown to emerge during manipulations of uncertainty, such as distraction. Similar phasic dopamine responses in the nucleus accumbens core occurred to both the occurrence and non-occurrence of the discriminative visual stimulus, showing for the first time that such dopaminergic responses are generated to interoceptive as well as exteroceptive discriminative stimuli. These observations thus enhance our understanding of the role of mesoaccumbens dopamine in perceptual decision-making.