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The Interaction between Externalizing Proneness and Striatal Dopamine on Distinct Aspects of Reward Processing
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Externalizing proneness, or impulse control and substance abuse problems, has been broadly associated with dysregulation in reward sensitivity. The goal of this investigation was to systematically determine the effects of distinct manifestations of externalizing proneness, namely disinhibition and substance abuse, on specific aspects of reward processing using a Research Domain Criteria approach. Additionally, this investigation examined whether striatal dopamine moderates the impact of externalizing proneness on reward processing. Striatal tonic dopamine levels were operationalized using spontaneous eyeblink rate. Participants completed disinhibition and substance abuse subscales of the brief form Externalizing Spectrum Inventory, and then performed assessments of reward wanting and learning, devaluation sensitivity, effort expenditure for rewards, and reward-incentivized cognitive control. Results revealed that disinhibition and substance abuse exerted unique effects on reward processing, which were moderated by variation in striatal dopamine levels. High-disinhibited individuals with low striatal dopamine showed greater reward wanting and preferred less physically effortful, smaller rewards. Individuals with substance abuse problems and high striatal dopamine showed enhanced long-term reward learning, while high substance users with low dopamine showed enhanced learning of immediately rewarding options, exerted greater cognitive effort to obtain rewards, and showed deficits in reward- incentivized cognitive control. Substance abuse, independent of striatal dopamine, was associated with reduced reward devaluation sensitivity. Collectively, these results suggest that in individuals with externalizing proneness, low striatal dopamine may represent a risk factor for addiction or elevated impulse control problems.
Byrne, Kaileigh A (2017). The Interaction between Externalizing Proneness and Striatal Dopamine on Distinct Aspects of Reward Processing. Doctoral dissertation, Texas A & M University. Available electronically from