Individual Differences in the Frontal - Striatal Reward Network : Decision - Making and Psychiatric Disease by Joshua

The frontal-striatal reward network is involved in many reward-related behaviors, including decision-making and those related to psychiatric disease. One important class of decisions involves the conflict between immediate rewards and delayed gratification. Temporal discounting preferences reflect how a person makes decisions that involve tradeoffs over time. A fundamental question is how people vary and what accounts for this variation in temporal discounting preferences, both behaviorally and neurobiologically. In addition, psychiatric diseases, such as social anxiety, are associated with deficits in behaviors that involve social reward. Here I report two experiments that provid -vidence for two major factors tacnriuetodifrnsintpra Fluvu VICkviu~i Wu LVVU Ilidjl IaL~ LLLUL UUl1LIUUL~ Lu U1L1c[eLes in temporal discounting preferences: personality traits and the underlying frontal-striatal reward network, both during task and at rest. Finally, I report underlying differences in the organization of the frontal-striatal reward network in social anxiety disorder. In the first study, I investigated the frontal-striatal reward network that underlies personality traits and the association of personality with temporal discounting preferences. Higher neuroticism was associated with a greater preference for immediate rewards and greater impulsivity, and higher conscientiousness with a greater preference for delayed rewards and less impulsivity. Executive-control and reward regions in the frontal-striatal reward network were more activated when higher conscientiousness participants selected a smaller-sooner reward and, conversely, when higher neuroticism participants selected a larger-later reward. Both cases involved choices that went against predispositions implied by personality. In the second study, I investigated how restingstate intrinsic functional brain organization (functional connectivity) of the frontal-striatal reward network varies with temporal discounting preferences. Increased patience and decreased impulsivity were associated with stronger functional connectivity between the nucleus accumbens and prefrontal executive control regions, including the dorsolateral prefrontal cortex. These findings reveal that the intrinsic strength of the frontal-striatal network is associated with differences in temporal discounting preferences. In the third study, I investigated the differences in the organization of the frontal-striatal reward