DESCRIPTION (provided by applicant): The development of drug addiction depends on the ability of drugs to activate the brain's "reward circuit," which acts to reinforce the drug-taking behavior. In order to gain insight into this process, it is important to understand the neural processes underlying reinforcement learning in the healthy brain. The striatum and orbitofrontal cortex (OFC), two key regions in the brain's reward circuit, are activated not only by drugs of abuse, but also by other rewards, such as food or money. Even rewards with no extrinsic value, such as positive feedback indicating a correct answer on a difficult task, engage this system, promoting learning from the performance-related feedback. It remains unclear, however, how contextual factors such as expectations of success influence processing in these brain regions, and in turn, the amount learned from feedback. Therefore, the proposed research uses feedback-based learning as a model system for understanding how expectations influence the neural processing of behavioral reinforcers. Participants will perform a feedback- based learning task during acquisition of functional magnetic resonance imaging (fMRI) data. Experiment 1 investigates how the abstract labels, "hard" and "easy," affect expectations of task difficulty and the neural processing of performance-related feedback. Experiment 2 manipulates difficulty expectations through a comparison with peer performance. False results from a pre-test will indicate to the participants that their performance is above or below average. The participants will then perform the feedback-based learning task as their brains are scanned with fMRI, allowing the effect of the ability labels on feedback-related signals in the striatum and OFC to be examined. These experiments will foster the initiation of a brain imaging research program on the neural mechanisms involved in motivated behavior. Such research may yield insights into how behavior could be motivated toward productive incentives, such as achievement, and away from harmful incentives, such as illicit drugs. PUBLIC HEALTH RELEVANCE: The proposed experiments examine contextual influences on the brain mechanisms involved in learning from behavioral reinforcers. These same mechanisms are involved in the development of drug addiction, so the research findings may suggest principles by which the ability of drugs to act as behavioral incentives could be altered through changes in motivational context.
|Effective start/end date||3/1/11 → 2/28/13|
- National Institutes of Health: $231,750.00