A specific role for serotonin in overcoming effort cost.
Serotonin is implicated in many aspects of behavioral regulation. Theoretical attempts to unify the multiple roles assigned to serotonin proposed that it regulates the impact of costs, such as delay or punishment, on action selection. Here, we show that serotonin also regulates other types of action costs such as effort. We compared behavioral performance in 58 healthy humans treated during 8 weeks with either placebo or the selective serotonin reuptake inhibitor escitalopram. The task involved trading handgrip force production against monetary benefits. Participants in the escitalopram group produced more effort and thereby achieved a higher payoff. Crucially, our computational analysis showed that this effect was underpinned by a specific reduction of effort cost, and not by any change in the weight of monetary incentives. This specific computational effect sheds new light on the physiological role of serotonin in behavioral regulation and on the clinical effect of drugs for depression.



ISRCTN75872983.
Motivation, Brain and Behavior team, Institut du Cerveau et de la Moelle épinière, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.|INSERM UMRS 1127, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC-P6), Paris, France.|Cognitive Neuroimaging Unit, NeuroSpin Center, INSERM U992, Institut d'Imagerie Biomédicale, Direction de la recherche fondamentale, Commissariat à l'énergie atomique et aux énergies alternatives, Gif-sur-Yvette, France.
Florent
0000-0002-6992-678X
F
Meyniel
Department of Psychiatry, University of Oxford, Oxford, United Kingdom.|Warneford Hospital, University of Oxford, Oxford, United Kingdom.
Guy M
GM
Goodwin
Neuroscience and Psychiatry Unit, The University of Manchester, Manchester, United Kingdom.
Jf William
0000-0002-2750-962X
JW
Deakin
Department of Psychiatry, University of Oxford, Oxford, United Kingdom.|Warneford Hospital, University of Oxford, Oxford, United Kingdom.
Corinna
C
Klinge
Department of Psychiatry, University of Oxford, Oxford, United Kingdom.|Warneford Hospital, University of Oxford, Oxford, United Kingdom.
Christine
C
MacFadyen
Neuroscience and Psychiatry Unit, The University of Manchester, Manchester, United Kingdom.
Holly
H
Milligan
Neuroscience and Psychiatry Unit, The University of Manchester, Manchester, United Kingdom.
Emma
E
Mullings
Motivation, Brain and Behavior team, Institut du Cerveau et de la Moelle épinière, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.|INSERM UMRS 1127, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC-P6), Paris, France.
Mathias
M
Pessiglione
Centre Hospitalier Sainte-Anne, Service de Psychiatrie, Paris, France.|Faculté de Médecine Paris Descartes, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.|Laboratoire de Physiopathologie des maladies Psychiatriques, Centre de Psychiatrie et Neurosciences, INSERM U894, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.|Human Histopathology and Animal Models, Department of Infection and Epidemiology, Institut Pasteur, Paris, France.
Raphaël
R
Gaillard
D000328:Adult; D001519:Behavior; D015283:Citalopram; D005260:Female; D018737:Hand Strength; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D010919:Placebos / Q000008:administration & dosage; D012201:Reward; D012701:Serotonin / Q000008:administration & dosage*; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage*; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage; D055815:Young Adult
D015283:Citalopram; D010919:Placebos; D012701:Serotonin; D017366:Serotonin Receptor Agonists; D017367:Selective Serotonin Reuptake Inhibitors
computational biology; decision-making; effort; escitalopram; human; neuroscience; reward; serotonin; systems biology