title: Dopamine-associated cached values are not sufficient as the basis for action selection.
abstract: Phasic dopamine transmission is posited to act as a critical teaching signal that updates the stored (or "cached") values assigned to reward-predictive stimuli and actions. It is widely hypothesized that these cached values determine the selection among multiple courses of action, a premise that has provided a foundation for contemporary theories of decision making. In the current work we used fast-scan cyclic voltammetry to probe dopamine-associated cached values from cue-evoked dopamine release in the nucleus accumbens of rats performing cost-benefit decision-making paradigms to evaluate critically the relationship between dopamine-associated cached values and preferences. By manipulating the amount of effort required to obtain rewards of different sizes, we were able to bias rats toward preferring an option yielding a high-value reward in some sessions and toward instead preferring an option yielding a low-value reward in others. Therefore, this approach permitted the investigation of dopamine-associated cached values in a context in which reward magnitude and subjective preference were dissociated. We observed greater cue-evoked mesolimbic dopamine release to options yielding the high-value reward even when rats preferred the option yielding the low-value reward. This result identifies a clear mismatch between the ordinal utility of the available options and the rank ordering of their cached values, thereby providing robust evidence that dopamine-associated cached values cannot be the sole determinant of choices in simple economic decision making.
authors.affiliation: Departments of Psychiatry and Behavioral Sciences and Pharmacology and Graduate Program in Neurobiology and Behavior, University of Washington, Seattle, WA 98195; and.
authors.forename: Nick G
authors.initials: NG
authors.lastname: Hollon
authors.affiliation: Departments of Psychiatry and Behavioral Sciences and Pharmacology and.
authors.forename: Monica M
authors.initials: MM
authors.lastname: Arnold
authors.affiliation: Departments of Psychiatry and Behavioral Sciences and Pharmacology and Graduate Program in Neurobiology and Behavior, University of Washington, Seattle, WA 98195; and.
authors.forename: Jerylin O
authors.initials: JO
authors.lastname: Gan
authors.affiliation: Departments of Psychiatry and Behavioral Sciences and Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, United Kingdom.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Walton
authors.affiliation: Departments of Psychiatry and Behavioral Sciences and Pharmacology and Graduate Program in Neurobiology and Behavior, University of Washington, Seattle, WA 98195; and pemp@uw.edu.
authors.forename: Paul E M
authors.initials: PE
authors.lastname: Phillips
mesh_terms: D000818:Animals; D003657:Decision Making; D004298:Dopamine / Q000378:metabolism / Q000502:physiology*; D009714:Nucleus Accumbens / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward
chemical_list: D004298:Dopamine
keywords: action selection; cached values; decision making; dopamine