Complementary roles of serotonin and dopamine in model-based learning
Year: 2024
Type: review
Abstract: Model-based learning involves building mental representations of predictive relationships between events. Although there is growing evidence clarifying the role of dopamine in model-based learning, we know less about how serotonin contributes to this process. Here, we present evidence demonstrating a role for serotonin neurons in the dorsal raphe nucleus (DRN) in regulating model-based learning. We contrast this to the role of ventral tegmental area dopamine neurons in this process. We further propose a new framework, suggesting how dopamine and serotonin influence model-based learning in unique but complementary ways. Specifically, we know that the phasic firing of dopamine neurons acts as teaching signals to drive model-based learning. In contrast, we argue that the sustained activity seen in DRN serotonin neurons during waiting for rewards or during the presentation of reward-predictive cues reflects a precise expectation of future rewards across multiple dimensions. These two systems allow us to refine our cognitive maps by interplexing different types of information. • Dopamine and serotonin play important roles in acquiring internal models of predictive relationships and using these learned representations to guide actions. • Dopamine neurons exhibit phasic activity to unexpected events, and causal studies have shown that phasic firing of dopamine neurons can act as a teaching signal to form associations between events regardless of their motivational significance or inherent value. • Serotonin neurons show sustained activity during waiting or reward-predictive cues later in learning, which often ramps up as subjects reach reward. • Sustained serotonin activity may relay precise expectations for upcoming rewards incorporating multidimensional aspects of the environment to facilitate adaptive behaviour.
Authors: Masakazu Taira, Melissa J Sharpe
Institution: The University of Sydney
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,840
OpenAlex ID: W4405039401