The association of rewards with specific actions is a common learning mechanism observed in day to day life that lead to predictions about potential rewards and shaping of behaviors. Over the years, research has suggested that one particular brain structure, the striatum, is a central region involved in how humans learn what decisions are advantageous (e.g., lead to reward). The goal of this proposal is to explore the neural substrates of human reward learning and decision-making processes drawing on two distinct methodologies in cognitive neuroscience: functional neuroimaging and experimental neuropsychology. Functional neuroimaging in healthy individuals can show whether a brain region is normally involved in a cognitive function; neuropsychological studies of individuals with damage localized to the same brain region can show whether or not that region is also necessary for that function. With support from the National Science Foundation, Drs. Mark Gluck, Mauricio Delgado and colleagues at Rutgers University propose to integrate both methodologies to investigate the role of the human striatum during (1) learning when reinforcement is directly contingent on actions as opposed to learning from passive observation, (2) learning when there is a delay between action and reinforcement. Parallel studies will be conducted in patients with striatal dysfunction due to lack of dopaminergic input that occurs in Parkinson's disease (PD) and neuroimaging studies of striatal function in healthy subjects.
Results from this research will contribute to a deeper understanding of the role of the striatum in decision making and in reward prediction, and of how the striatum, and related brain regions, utilize prediction-error feedback. This research builds on prior studies of the role of the basal ganglia in feedback learning, but also expands into new and more complex cognitive domains, including the creation of chains of linked predictions about sequences of actions. Learning to predict future rewards and other positive outcomes is fundamental to our survival in a complex, dynamic and uncertain world; it provides essential knowledge for making decisions that critically affect our lives, and the lives of those around us. The findings could influence interdisciplinary research in economics and neuroscience concerned about the mechanisms of how humans make decisions. Further, the research will give us a deeper understanding of the non-motoric, more motivational deficits associated with PD, eliciting new ideas for future research directions. Finally, the proposal aims to increase training opportunities for undergraduate, graduate and post-doctoral trainees in both neuropsychology and functional neuroimaging.
