Signed and unsigned reward prediction errors dynamically enhance learning and memory

Abstract
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Abstract

Memory helps guide behavior, but which experiences from the past are prioritized? Classic models of learning posit that events associated with unpredictable outcomes as well as, paradoxically, predictable outcomes, deploy more attention and learning for those events. Here, we test reinforcement learning and subsequent memory for those events, and treat signed and unsigned reward prediction errors (RPEs), experienced at the reward-predictive cue or reward outcome, as drivers of these two seemingly contradictory signals. By fitting reinforcement learning models to behavior, we find that both RPEs contribute to learning by modulating a dynamically changing learning rate. We further characterize the effects of these RPE signals on memory, and show that both signed and unsigned RPEs enhance memory, in line with midbrain dopamine and locus-coeruleus modulation of hippocampal plasticity, thereby reconciling separate findings in the literature.

Data availability

All data files and code for models, analysis and figures are publicly available at https://github.com/ninarouhani/2021_RouhaniNiv

The following data sets were generated

1. Rouhani N
2. Niv Y
(2021) 2021_RouhaniNiv
github.

https://github.com/ninarouhani/2021_RouhaniNiv

Article and author information

Author details

Nina Rouhani

Princeton Neuroscience Institute, Princeton University, Princeton, United States

For correspondence
nrouhani@princeton.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-2814-0462
Yael Niv

Princeton Neuroscience Institute, Princeton University, Princeton, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-0259-8371

Funding

Army Research Office (W911NF-14-1-0101)

Yael Niv

National Institute of Mental Health (R01MH098861)

Yael Niv

National Science Foundation (Graduate Student Fellowship)

Nina Rouhani

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

Ethics

Human subjects: We obtained informed consent online; procedures were approved by Princeton University's Institutional Review Board (IRB #4452).

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.