title: A critical role for the hippocampus in the valuation of imagined outcomes.
abstract: Many choice situations require imagining potential outcomes, a capacity that was shown to involve memory brain regions such as the hippocampus. We reasoned that the quality of hippocampus-mediated simulation might therefore condition the subjective value assigned to imagined outcomes. We developed a novel paradigm to assess the impact of hippocampus structure and function on the propensity to favor imagined outcomes in the context of intertemporal choices. The ecological condition opposed immediate options presented as pictures (hence directly observable) to delayed options presented as texts (hence requiring mental stimulation). To avoid confounding simulation process with delay discounting, we compared this ecological condition to control conditions using the same temporal labels while keeping constant the presentation mode. Behavioral data showed that participants who imagined future options with greater details rated them as more likeable. Functional MRI data confirmed that hippocampus activity could account for subjects assigning higher values to simulated options. Structural MRI data suggested that grey matter density was a significant predictor of hippocampus activation, and therefore of the propensity to favor simulated options. Conversely, patients with hippocampus atrophy due to Alzheimer's disease, but not patients with Fronto-Temporal Dementia, were less inclined to favor options that required mental simulation. We conclude that hippocampus-mediated simulation plays a critical role in providing the motivation to pursue goals that are not present to our senses.
authors.affiliation: Motivation, Brain and Behavior (MBB) Team, Institut du Cerveau et de la Moelle Epinière (ICM), Paris, France ; Service de Neuroradiologie, Hôpital Pitie-Salpetriere, Centre de NeuroImagerie de Recherche (CENIR), Institut du Cerveau et de la Moelle épinière (ICM), Paris, France ; INSERM UMRS 975, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC - Paris 6), Paris, France.
authors.forename: Maël
authors.initials: M
authors.lastname: Lebreton
authors.forename: Maxime
authors.initials: M
authors.lastname: Bertoux
authors.forename: Claire
authors.initials: C
authors.lastname: Boutet
authors.forename: Stéphane
authors.initials: S
authors.lastname: Lehericy
authors.forename: Bruno
authors.initials: B
authors.lastname: Dubois
authors.forename: Philippe
authors.initials: P
authors.lastname: Fossati
authors.forename: Mathias
authors.initials: M
authors.lastname: Pessiglione
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000473:pathology / Q000503:physiopathology; D001284:Atrophy / Q000473:pathology / Q000503:physiopathology; D001931:Brain Mapping; D002755:Choice Behavior; D003657:Decision Making; D005260:Female; D057180:Frontotemporal Dementia / Q000473:pathology / Q000503:physiopathology; D006262:Health; D006624:Hippocampus / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007092:Imagination; D007175:Impulsive Behavior / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D013647:Task Performance and Analysis