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UBC Theses and Dissertations

Mesolimbic dopaminergic modulation of cue-guided risk-reward decision making Schofield-Lewis, Shayden


In naturalistic decision making, we are often presented with options that provide a small reward with a high degree of certainty, or riskier options with a larger reward at the cost of higher uncertainty. Human models of decision making often provide participants with external cues to guide subsequent decisions, however in rodent models of decision making it is common for the animal to develop an internal model of decision making in response to previous choice outcomes. To bridge the gap between human and rodent models of externally guided decision making, our lab has developed the “blackjack task”, where animals listen for an external auditory cue which signals the probability of a larger, riskier reward being delivered with favourable odds (50%) or unfavourable odds (12.5%) in comparison to a smaller reward delivered with 100% certainty. Both human and rodent studies have verified the importance of dopamine (DA) transmission in nucleus accumbens (NAc) and its core and shell subregions in the modulation of such risk-reward decision making. Here, we further clarify this role by delivering intracranial infusions of D1 or D2 antagonists directly into the NAc core or shell. It was found that D2 but surprisingly not D1 receptors modulate risk-reward decision making differentially in the NAc core versus NAc shell. D2 blockade in the NAc core blunted risky choice, while D2 blockade in the NAc shell heightened risky choice. These data contribute to the understanding that externally guided risk-reward decision making is affected differently by DA receptors, and that this effect is also subregion dependent.

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