title: Modulation of impulsivity and reward sensitivity in intertemporal choice by striatal and midbrain dopamine synthesis in healthy adults.
abstract: Converging evidence links individual differences in mesolimbic and mesocortical dopamine (DA) to variation in the tendency to choose immediate rewards ("Now") over larger, delayed rewards ("Later"), or "Now bias." However, to date, no study of healthy young adults has evaluated the relationship between Now bias and DA with positron emission tomography (PET). Sixteen healthy adults (ages 24-34 yr; 50% women) completed a delay-discounting task that quantified aspects of intertemporal reward choice, including Now bias and reward magnitude sensitivity. Participants also underwent PET scanning with 6-[(18)F]fluoro-l-m-tyrosine (FMT), a radiotracer that measures DA synthesis capacity. Lower putamen FMT signal predicted elevated Now bias, a more rapidly declining discount rate with increasing delay time, and reduced willingness to accept low-interest-rate delayed rewards. In contrast, lower FMT signal in the midbrain predicted greater sensitivity to increasing magnitude of the Later reward. These data demonstrate that intertemporal reward choice in healthy humans varies with region-specific measures of DA processing, with regionally distinct associations with sensitivity to delay and to reward magnitude.
authors.affiliation: Neurobiology Curriculum, University of North Carolina, Chapel Hill, North Carolina;
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Smith
authors.affiliation: Helen Wills Neuroscience Institute, University of California, Berkeley, California;
authors.forename: Deanna L
authors.initials: DL
authors.lastname: Wallace
authors.affiliation: Helen Wills Neuroscience Institute, University of California, Berkeley, California; Lawrence Berkeley National Laboratory, Berkeley, California;
authors.forename: Linh C
authors.initials: LC
authors.lastname: Dang
authors.affiliation: Helen Wills Neuroscience Institute, University of California, Berkeley, California; Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands; and.
authors.forename: Esther
authors.initials: E
authors.lastname: Aarts
authors.affiliation: Helen Wills Neuroscience Institute, University of California, Berkeley, California; Lawrence Berkeley National Laboratory, Berkeley, California;
authors.forename: William J
authors.initials: WJ
authors.lastname: Jagust
authors.affiliation: Helen Wills Neuroscience Institute, University of California, Berkeley, California;
authors.forename: Mark
authors.initials: M
authors.lastname: D'Esposito
authors.affiliation: Neurobiology Curriculum, University of North Carolina, Chapel Hill, North Carolina; Department of Psychology & Neuroscience, Bowles Center for Alcohol Studies, and Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, North Carolina cab@unc.edu.
authors.forename: Charlotte A
authors.identifier: http://orcid.org/0000-0003-1853-1574
authors.initials: CA
authors.lastname: Boettiger
mesh_terms: D000328:Adult; D002755:Choice Behavior; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D006801:Humans; D007175:Impulsive Behavior; D008297:Male; D008636:Mesencephalon / Q000000981:diagnostic imaging / Q000378:metabolism / Q000502:physiology*; D049268:Positron-Emission Tomography; D011699:Putamen / Q000000981:diagnostic imaging / Q000378:metabolism / Q000502:physiology*; D019275:Radiopharmaceuticals; D011930:Reaction Time; D012201:Reward; D014443:Tyrosine / Q000031:analogs & derivatives
chemical_list: C496696:6-fluoro-3-hydroxyphenylalanine; D019275:Radiopharmaceuticals; D014443:Tyrosine; D004298:Dopamine
keywords: delay discounting; immediate reward bias; impulsive choice; putamen; ventral tegmental area