title: Mesolimbic dopamine dynamically tracks, and is causally linked to, discrete aspects of value-based decision making.
abstract: BACKGROUND
  To make appropriate choices, organisms must weigh the costs and benefits of potential valuable outcomes, a process known to involve the nucleus accumbens (NAc) and its dopaminergic input. However, it is currently unknown if dopamine dynamically tracks alterations in expected reward value online as behavioral preferences change and if so, if it is causally linked to specific components of value such as reward magnitude and/or delay to reinforcement.
  
  
  METHODS
  Electrochemical methods were used to measure subsecond NAc dopamine release during a delay discounting task where magnitude was fixed but delay varied across blocks (n = 7 rats). Next, to assess whether this dopamine signaling was causally related to specific components of choice behavior, we employed selective optogenetic stimulation of dopamine terminals in the NAc using a modified delay discounting task in which both delay and magnitude varied independently (n = 23 rats).
  
  
  RESULTS
  Cues predictive of available choices evoked dopamine release that scaled with the rat's preferred choices and dynamically shifted as delay to reinforcement for the large reward increased. In the second experiment, dopamine signaling was causally related to features of decision making, as optogenetically enhanced dopamine release within the NAc during predictive cue presentation was sufficient to alter subsequent value-related choices. Importantly, this dopamine-mediated shift in choice was limited to delay-based, but not magnitude-based, decisions.
  
  
  CONCLUSIONS
  These findings indicate that NAc dopamine dynamically tracks delay discounting and establishes a causal role for this signaling in a subset of value-based associative strategies.
authors.affiliation: Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Saddoris
authors.affiliation: Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Sugam
authors.affiliation: Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.|Department of Cell Biology and Physiology University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.|Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Garret D
authors.initials: GD
authors.lastname: Stuber
authors.affiliation: Psychology Department, Princeton University, Princeton, New Jersey 08540.
authors.forename: Ilana B
authors.initials: IB
authors.lastname: Witten
authors.affiliation: Department of Bioengineering, Stanford University School of Medicine, Stanford, CA 94305, USA.|Department of Psychiatry, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Karl
authors.initials: K
authors.lastname: Deisseroth
authors.affiliation: Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.|Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Regina M
authors.initials: RM
authors.lastname: Carelli
mesh_terms: D000818:Animals; D003657:Decision Making / Q000502:physiology*; D065786:Delay Discounting / Q000502:physiology; D004298:Dopamine / Q000378:metabolism / Q000502:physiology*; D008297:Male; D009714:Nucleus Accumbens / Q000378:metabolism / Q000502:physiology*; D062308:Optogenetics; D020318:Rats, Long-Evans; D017207:Rats, Sprague-Dawley; D012201:Reward
chemical_list: D004298:Dopamine
keywords: Decision making; Dopamine; Nucleus accumbens; Optogenetics; Reward; Value