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| Type | Journal Article |
| Scope | Discipline-based scholarship |
| Title | Arbitration between model-free and model-based control is not affected by transient changes in tonic serotonin levels |
| Organization Unit | |
| Authors |
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| Item Subtype | Original Work |
| Refereed | Yes |
| Status | Published in final form |
| Language |
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| Journal Title | Journal of Psychopharmacology |
| Publisher | Sage Publications |
| Geographical Reach | international |
| ISSN | 0269-8811 |
| Volume | 38 |
| Number | 2 |
| Page Range | 178 - 187 |
| Date | 2024 |
| Abstract Text | Background: Serotonin has been suggested to modulate decision-making by influencing the arbitration between model-based and model-free control. Disruptions in these control mechanisms are involved in mental disorders such as drug dependence or obsessive-compulsive disorder. While previous reports indicate that lower brain serotonin levels reduce model-based control, it remains unknown whether increases in serotonergic availability might thus increase model-based control. Moreover, the mediating neural mechanisms have not been studied yet. Aim: The first aim of this study was to investigate whether increased/decreased tonic serotonin levels affect the arbitration between model-free and model-based control. Second, we aimed to identify the underlying neural processes. Methods: We employed a sequential two-stage Markov decision-task and measured brain responses during functional magnetic resonance imaging in 98 participants in a randomized, double-blind cross-over within-subject design. To investigate the influence of serotonin on the balance between model-free and model-based control, we used a tryptophan intervention with three intervention levels (loading, balanced, depletion). We hypothesized that model-based behaviour would increase with higher serotonin levels. Results: We found evidence that neither model-free nor model-based control were affected by changes in tonic serotonin levels. Furthermore, our tryptophan intervention did not elicit relevant changes in Blood-Oxygenation-Level Dependent activity. |
| Digital Object Identifier | 10.1177/02698811231216325 |
| Other Identification Number | merlin-id:24352 |
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| Keywords | Pharmacology (medical), psychiatry and mental health, pharmacology, tryptophan loading, tryptophan depletion, habitual system, goal-directed system, two-stage Markov decision task |