Dopamine, however, may influence non-affective aspects of decision-making related to learning and evaluating risk and reward levels. Although the effects are not uniform, pharmacologic stimulation and suppression of the dopamine system using systemic D1 and D2 receptor agonists and antagonists can bias choice behavior in some rodent tasks.219, 221, 222, 252 These effects may involve activity at D1 dopamine receptors (but not D2) in the nucleus accumbens.253 Microdialysis measurement of dopamine efflux during the Probabilistic Discounting Task in the prefrontal cortex and nucleus accumbens respectively suggests that the former encodes relative reward rate or availability while the latter encodes an integration of reward rate, uncertainty and preference, and decision information.254 Additionally, striatal D2/D3 density as assessed by micro-PET in rats was negatively correlated with wager-sensitivity in The Betting Task,223 implicating this system in irrational choice bias in the face of uncertainty. In sum, aggregate data indicates that dopamine signaling in brain regions implicated in decision-making and learning processes influence behavior in these risky decision-making tasks, but the precise mapping of signals at specific receptor subtypes in these networks onto specific decision-making related functions remains to be resolved.
