Nature Communications: PET-measured Human Dopamine Synthesis Capacity and Receptor Availability Predict Trading Rewards and Time-costs during Foraging
Foraging is a type of reward-guided behavior in which a decision is made by weighing potential rewards available in the current environment versus the cost of lost time traveling to a new environment. In other words, when the current setting is less rewarding than the average experience, it is optimal to leave and search for something that is likely to be better. Although striatal dopamine is key to this process, the specific role of dopamine in foraging behavior in humans is not well characterized.
To gain an improved understanding of the role of dopamine in foraging behavior, Angela Ianni, MD, DPhil (PGY4 psychiatry resident), and collaborators from multiple institutions—including her DPhil mentors Karen Berman, MD (NIMH) and Tim Behrens, DPhil (University of Oxford)—used positron emission tomography (PET) imaging to directly measure dopamine synthesis capacity and D1 and D2/3 receptor availability in 57 healthy adults who complete a computerized foraging task. They hypothesized that individuals with higher dopamine synthesis capacity and receptor availability would enact greater adjustments in the threshold for leaving a reward cluster as the reward environment changed.
The team found that found that the degree to which individuals change their foraging behavior based on the parameters of the experimental reward environment is correlated with two patterns of dopamine synthesis capacity and receptor availability throughout the basal ganglia and anterior cingulate cortex. Additionally, they found that these patterns of dopamine function were specifically associated with behavioral adjustments due to changes in travel-time costs, suggesting a role of dopamine in tracking the opportunity cost of time.
“The results from this unique multi-tracer PET study provide insight into the role of dopamine D1 and D2/3 receptors in adjusting decisions about balancing rewards against time-costs during foraging. This provides a foundation for understanding the neural mechanisms underlying decisions about how to spend time. I hope to extend this work to try to understand how these mechanisms are modified in psychiatric illnesses involving dopamine dysfunction and decision-making impairments,” said Dr. Ianni, the study’s corresponding author.
PET-measured human dopamine synthesis capacity and receptor availability predict trading rewards and time-costs during foraging
Ianni AM, Eisenberg DP, Boorman ED, Constantino SM, Hegarty CE, Gregory MD, Masdeu JC, Kohn PD, Behrens TE, Berman KF
Nature Communications 14, 6122 (2023). https://doi.org/10.1038/s41467-023-41897-0