Choices made between outcomes available at different points in the future (intertemporal choices) constitute an important and common set of decisions encountered in everyday life. How people respond to such choices is also known to be predictive of a number of important life outcomes, and can be summarized using laboratory measures of delay discounting. Understanding the cognitive brain processes that underlie delay discounting, and particularly our ability to resist immediate temptations, is an important area of research in cognitive neuroscience. Significant progress has been made in this area over the past decade. It is now well established that brain reward areas, including the ventromedial prefrontal cortex (vmPFC), encode the subjective value of prospective rewards. It is also established that a network of regions in lateral prefrontal (lPFC), dorsomedial frontal (dmFC), and posterior parietal cortex (pPC) are engaged when making intertemporal choices. However, the role of this fronto-parietal cortical network (FPN) remains debated and less understood. The current research project builds on recent computational modeling work done by McClure and his colleagues to test and unify competing theories of FPN function in delay discounting. This work promises to further our understanding of the brain basis of important cognitive processes related to the exertion of willpower and self-control.
We will conduct three studies that employ both fMRI and EEG to investigate the role of different frontal and parietal regions in intertemporal decision-making. In preliminary work, we have used our computation model framework to demonstrate that (1) the pPC interacts with the vmPFC during the valuing of choice options, and (2) value information is accumulated in the dmFC during action selection. This project will further test how the FPN functions under conditions of temptation and cognitive load and how these manipulations influence choice outcomes. A number of disorders, including attention deficit hyperactivity disorder and drug addiction, have been directly associated with delay discounting. The proposed studies of delay discounting therefore represent a clear example in which cognitive neuroscience approaches promise to directly impact and improve our understanding of normal and aberrant behavior. Finally, decision neuroscience is a highly interdisciplinary field that combines elements of economics, psychology, and neuroscience. It offers an exciting training opportunity for the students at various levels of training who will be directly involved in the project.