Reinforcement learning is the process by which individuals alter their decisions to maximize positive outcomes, and minimize negative outcomes. It is a cognitive process that is widely used in our daily lives and is often disrupted during psychiatric disease. Thus, a major goal of neuroscience is to characterize the neural underpinnings of reinforcement learning. Whereas animal studies have utilized invasive physiological methods to characterize several neural mechanisms that underlie reinforcement learning, human studies have largely relied on non-invasive techniques that have reduced physiological precision. Although ethical limitations preclude the use of invasive physiological methods in healthy human populations, patient populations undergoing certain neurosurgical interventions offer a rare opportunity to directly assay neural activity from the brain during human reinforcement learning. This dissertation presents early findings from this research effort.