Dopamine neurons learn relative chosen value from probabilistic rewards

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Abstract

Economic theories posit reward probability as one of the factors defining reward value. Individuals learn the value of cues that predict probabilistic rewards from experienced reward frequencies. Building on the notion that responses of dopamine neurons increase with reward probability and expected value, we asked how dopamine neurons in monkeys acquire this value signal that may represent an economic decision variable. We found in a Pavlovian learning task that reward probability-dependent value signals arose from experienced reward frequencies. We then assessed neuronal response acquisition during choices among probabilistic rewards. Here, dopamine responses became sensitive to the value of both chosen and unchosen options. Both experiments showed also the novelty responses of dopamine neurones that decreased as learning advanced. These results show that dopamine neurons acquire predictive value signals from the frequency of experienced rewards. This flexible and fast signal reflects a specific decision variable and could update neuronal decision mechanisms.

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Armin Lak

Institute of Ophthalmology, University College London, London, United Kingdom

For correspondence
arminlak@gmail.com

Competing interests
No competing interests declared.

"This ORCID iD identifies the author of this article:" 0000-0003-1926-5458
William R Stauffer

Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge, United Kingdom

Competing interests
No competing interests declared.
Wolfram Schultz

Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge, United Kingdom

Competing interests
Wolfram Schultz, Reviewing editor, eLife.

"This ORCID iD identifies the author of this article:" 0000-0002-8530-4518

Funding

Wellcome (WT106101)

Armin Lak

Wellcome

Wolfram Schultz

European Research Council

Wolfram Schultz

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: All experimental protocols and procedures were approved by the Home Office of the United Kingdom (project licence number: 80 / 2416).

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.