Dopamine-associated cached values are not sufficient as the basis for action selection.

Journal article

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: Hollon, N; Arnold, M; Gan, J; Walton, M; Phillips, P

• Publisher: National Academy of Sciences
• Journal: Proceedings of the National Academy of Sciences of the United States of America
• Volume: 111
• Issue: 51
• Pages: 18357-18362
• Publication date: 2014-12-01
• DOI: 10.1073/pnas.1419770111
• EISSN: 1091-6490
• ISSN: 0027-8424
• Language: English
• Keywords: action selection; cached values; decision making; dopamine