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UBC Theses and Dissertations

A dissociable role for dopamine receptors in the basolateral amygdala in risk/reward decision making Larkin, Joshua Daniel


Different aspects of cost/benefit decision making involving uncertain rewards are facilitated by distributed corticolimbic circuits linking different regions of the prefrontal cortex, ventral striatum and the basolateral amygdala (BLA). Dopamine (DA) also plays an integral role in promoting choice of larger, uncertain rewards, as manipulations of DA transmission the PFC or nucleus accumbens alters risky choice. However, considerably less is known about how DA activity within the BLA regulates risk-based decision making. The present study assessed the effects of DA receptor modulation within the BLA on risk-based decision making, utilizing a probabilistic discounting task. Rats were trained to choose between a small/certain lever (1 sugar pellet) and a large/risky lever (4 sugar pellets) delivered in a probabilistic manner. The odds of obtaining the larger reward decreased in a systematic manner across 4 blocks of trials (100%, 50%, 25%, & 12.5%) during a daily session. Animals received counterbalanced intra-BLA microinfusions of the D1 receptor antagonist SCH23390, D2 antagonist eticlopride, the D1 agonist SKF81297 or D2 agonist quinpirole. Blockade of D1 receptors in the BLA caused rats to discount the larger/uncertain reward significantly more when compared to their performance after saline infusions, resulting in a reduction in risky choice most prominently during blocks where delivery of the larger reward was uncertain. Further, stimulation of the D1 receptor produced an optimization effect on choice behavior, increasing risky choice when it is more advantageous and decreasing risky choice when it is not advantageous. D1 receptors in the BLA seem to have an important role in facilitating optimal decision making and promoting choice of larger uncertain rewards. D2 receptor blockade showed a significant reduction in reward sensitivity, while stimulation of the D2 receptor did not affect choice behavior. More generally, these findings highlight a key contribution by mesoamygdala DA in regulating certain aspects of cost/benefit decision making, particularly the D1 receptor which may be the primary mechanism through which DA exerts its effect the BLA. These findings may have important implications to understanding mechanisms underlying disruptions in decision making and reward processes in psychiatric disorders linked to dysfunction of the DA system and the amygdala.

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Attribution-NoDerivs 2.5 Canada