Control of patience and serotonin

Kenji Doya, PhD
Okinawa Institute of Science and Technology

Talk Abstract: Evaluation of delayed reward is an essential component of intelligence and also critical in economic decision making. We hypothesized that the brain’s serotonergic system regulates the temporal discounting of future rewards. Human brain imaging experiments showed that different cortico-basalganglia loops are involved in reward prediction in different time scales and that they are differentially modulated by  serotonerin. Chemical recording and manipulation in rats showed that serotonin release is elevated when animals are engaged in delayed reward tasks and that suppression of dorsal raphe serotonin neurons increase reward waiting errors. Electrode recording of dorsal raphe neurons revealed that their firing increases during reward waiting period and drops just before the animal abandons waiting. Optogenetic activation of dorsal raphe serotonin neurons reduced waiting errors and extended waiting time in reward omission trials. These results showed that dorsal raphe serotonin neurons control the patience for delayed rewards in a dynamic way.