title: Valence-dependent influence of serotonin depletion on model-based choice strategy.
abstract: Human decision-making arises from both reflective and reflexive mechanisms, which underpin goal-directed and habitual behavioural control. Computationally, these two systems of behavioural control have been described by different learning algorithms, model-based and model-free learning, respectively. Here, we investigated the effect of diminished serotonin (5-hydroxytryptamine) neurotransmission using dietary tryptophan depletion (TD) in healthy volunteers on the performance of a two-stage decision-making task, which allows discrimination between model-free and model-based behavioural strategies. A novel version of the task was used, which not only examined choice balance for monetary reward but also for punishment (monetary loss). TD impaired goal-directed (model-based) behaviour in the reward condition, but promoted it under punishment. This effect on appetitive and aversive goal-directed behaviour is likely mediated by alteration of the average reward representation produced by TD, which is consistent with previous studies. Overall, the major implication of this study is that serotonin differentially affects goal-directed learning as a function of affective valence. These findings are relevant for a further understanding of psychiatric disorders associated with breakdown of goal-directed behavioural control such as obsessive-compulsive disorders or addictions.
authors: Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK.
authors: Y
authors: Y
authors: Worbe
authors: Institute of Cognitive science, University College of London, London, UK.|Laboratoire des Neurosciences Cognitives, Ecole Normal Supérieure, Paris, France.
authors: S
authors: S
authors: Palminteri
authors: Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK.|Department of Psychiatry, University of Cambridge, Cambridge, UK.
authors: G
authors: G
authors: Savulich
authors: Center for Neural Science and Department of Psychology, New York University, NY, USA.
authors: N D
authors: ND
authors: Daw
authors: Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK.|Department of Psychiatry, University of Cambridge, Cambridge, UK.|Cambridgeshere and Peterborough NHS Foundation Trust, Cambridge, UK.
authors: E
authors: E
authors: Fernandez-Egea
authors: Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK.|Department of Psychology, University of Cambridge, Cambridge, UK.
authors: T W
authors: TW
authors: Robbins
authors: Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK.|Department of Psychiatry, University of Cambridge, Cambridge, UK.
authors: V
authors: V
authors: Voon
mesh_terms: D000328:Adult; D001070:Appetitive Behavior / Q000502:physiology; D002755:Choice Behavior / Q000502:physiology*; D004032:Diet; D004311:Double-Blind Method; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008960:Models, Psychological; D009483:Neuropsychological Tests; D011678:Punishment; D012201:Reward; D012701:Serotonin / Q000172:deficiency*; D014364:Tryptophan / Q000172:deficiency*
chemical_list: D012701:Serotonin; D014364:Tryptophan