Serotonin differentially regulates short- and long-term prediction of rewards in the ventral and dorsal striatum.
BACKGROUND
The ability to select an action by considering both delays and amount of reward outcome is critical for maximizing long-term benefits. Although previous animal experiments on impulsivity have suggested a role of serotonin in behaviors requiring prediction of delayed rewards, the underlying neural mechanism is unclear.


RESULTS
To elucidate the role of serotonin in the evaluation of delayed rewards, we performed a functional brain imaging experiment in which subjects chose small-immediate or large-delayed liquid rewards under dietary regulation of tryptophan, a precursor of serotonin. A model-based analysis revealed that the activity of the ventral part of the striatum was correlated with reward prediction at shorter time scales, and this correlated activity was stronger at low serotonin levels. By contrast, the activity of the dorsal part of the striatum was correlated with reward prediction at longer time scales, and this correlated activity was stronger at high serotonin levels.


CONCLUSIONS
Our results suggest that serotonin controls the time scale of reward prediction by differentially regulating activities within the striatum.
Tanaka
Saori C
SC
Department of Computational Neurobiology, ATR Computational Neuroscience Laboratories, Seika, Souraku, Kyoto, Japan. xsaori@atr.jp
Schweighofer
Nicolas
N
Asahi
Shuji
S
Shishida
Kazuhiro
K
Okamoto
Yasumasa
Y
Yamawaki
Shigeto
S
Doya
Kenji
K
D003342:Corpus Striatum / Q000502:physiology*; D004311:Double-Blind Method; D006801:Humans; D008279:Magnetic Resonance Imaging; D009042:Motivation; D012044:Regression Analysis; D012701:Serotonin / Q000502:physiology*
D012701:Serotonin