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Dopamine modulates adaptive prediction error coding in the human midbrain and striatum

Accepted version
Peer-reviewed

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Authors

Diederen, KMJ 
Vestergaard, MD 
Spencer, T 

Abstract

Learning to optimally predict rewards requires agents to account for fluctuations in reward value. Recent work suggests that individuals can efficiently learn about variable rewards through adaptation of the learning rate, and coding of prediction errors relative to reward variability. Such adaptive coding has been linked to midbrain dopamine neurons in non-human primates, and evidence in support for a similar role of the dopaminergic system in humans is emerging from fMRI data. Here, we sought to investigate the effect of dopaminergic perturbations on adaptive prediction error coding in humans, using a between-subject, placebo-controlled pharmacological fMRI study with a dopaminergic agonist (bromocriptine) and antagonist (sulpiride). Participants performed a previously validated task in which they predicted the magnitude of upcoming rewards drawn from distributions with varying standard deviations. After each prediction, participants received a reward, yielding trial- by-trial prediction errors. Under placebo, we replicated previous observations of adaptive coding in the midbrain and ventral striatum. Treatment with sulpiride attenuated adaptive coding in both midbrain and ventral striatum, and was associated with a decrease in performance, whereas bromocriptine did not have a significant impact. Although we observed no differential effect of SD on performance between the groups, computational modelling suggested decreased behavioral adaptation in the sulpiride group. These results suggest that normal dopaminergic function is critical for adaptive prediction error coding, a key property of the brain thought to facilitate efficient learning in variable environments. Crucially, these results also offer potential insights for understanding the impact of disrupted dopamine function in mental illness.

Description

Keywords

dopamine, adaptation, prediction errors, fMRI, reward, pharmacological intervention

Journal Title

The Journal of Neuroscience

Conference Name

Journal ISSN

0270-6474
1529-2401

Volume Title

37

Publisher

Society for Neuroscience
Sponsorship
Wellcome Trust, Bernard Wolfe Health Neuroscience Fund, Niels Stensen Foundation