Sleep deprivation (SD) has detrimental effects on cognition, but the affected psychological processes and underlying neural mechanisms are still essentially unclear. Here we combined functional magnetic resonance imaging and computational modeling to examine how SD alters neural representation of specific choice variables (subjective value and decision conflict) during reward-related decision making. Twenty-two human subjects underwent two functional neuroimaging sessions in counterbalanced order, once during rested wakefulness and once after 24 h of SD. Behaviorally, SD attenuated conflict-dependent slowing of response times, which was reflected in an attenuated conflict-induced decrease in drift rates in the drift diffusion model. Furthermore, SD increased overall choice stochasticity during risky choice. Model-based functional neuroimaging revealed attenuated parametric subjective value signals in the midbrain, parietal cortex, and ventromedial prefrontal cortex after SD. Conflict-related midbrain signals showed a similar downregulation. Findings are discussed with respect to changes in dopaminergic signaling associated with the sleep-deprived state.
