Abstract:

Discusses a neural network model concerning the apparent opponent partnership of serotonin and dopamine. Anatomical and pharmacological evidence suggests that the dorsal raphe serotonin system and the ventral tegmental and substantia nigra dopamine system may act as mutual opponents. In the light of the temporal difference model of the involvement of the dopamine system in reward learning, the proposed model incorporates 3 aspects of motivational opponency involving dopamine and serotonin: (1) a tonic serotonergic signal reports the long-run average reward rate as part of an average-case reinforcement learning model; (2) a tonic dopaminergic signal reports the long-run average punishment rate in a similar context; and (3) a phasic serotonin signal might report an ongoing prediction error for future punishment. (PsycINFO Database Record (c) 2016 APA, all rights reserved)