Dopaminergic control of neuroeconomic decision making

Abstract

Dopamine in the nucleus accumbens is an important neural substrate for valuation and decision-making. Dominant theories generally discretize and homogenize decision-making, when it is in fact a continuous process, with evaluation and re-evaluation components that extend beyond simple outcome prediction into consideration of past and future value. Furthermore, individual animals use distinct strategies to achieve their goals, requiring different computational processes. Extensive work has examined mesolimbic dopamine in the context of reward prediction error, but major gaps persist in our understanding of how dopamine tracks imagined past and future rewards to influence decision confidence. Moreover, there is little consideration of strategy-dependent differences in value processing that may shape dopaminergic encoding. In the studies presented in this dissertation we used an economic foraging task in mice, and found that strategy-specific dopamine dynamics reflected decision confidence during evaluation, as well as both past and future counterfactual value during re-evaluation. We found that inhibition of dopamine terminals altered counterfactual processing during re-evaluation. Individually-tailored optogenetic stimulation of mesolimbic dopamine terminals altered decision confidence during evaluation and carried over to counterfactual re-evaluation, in a strategy-specific manner. We provide evidence that mesolimbic dopamine is tightly linked to decision confidence and counterfactual information, through signals that go beyond reward prediction errors to more complex encoding of imagined past and future value.