dc.contributor.author | Halahakoon, Don Chamith | |
dc.contributor.author | Geddes, John R | |
dc.contributor.author | Cowen, Philip J | |
dc.contributor.author | Harmer, Catherine J | |
dc.contributor.author | Browning, Michael | |
dc.date.accessioned | 2022-03-28T19:13:27Z | |
dc.date.available | 2022-03-28T19:13:27Z | |
dc.date.issued | 2022-01 | |
dc.identifier.citation | Don Chamith Halahakoon, Alexander Kaltenboeck, Marieke Martens, John G. Geddes, Catherine J. Harmer, Philip Cowen, Michael Browning. Pramipexole Enhances Reward Learning by Preserving Value Estimates. MedRXIV 14 January 2022 | en |
dc.identifier.uri | https://oxfordhealth-nhs.archive.knowledgearc.net/handle/123456789/1026 | |
dc.description.abstract | Background: Dopamine D2-like receptor agonists show promise as treatments for depression. They are
thought to act by altering how individuals learn from rewarding experiences. However, the nature of these
reward learning alterations, and the mechanisms by which they are produced is not clear. Reinforcement
learning accounts describe three distinct processes that may produce similar changes in reward learning
behaviour; increased reward sensitivity, increased inverse decision temperature and decreased value
decay. As these processes produce equivalent effects on behaviour, arbitrating between them requires
measurement of how expectations and prediction errors are altered. In the present study, we characterised
the behavioural effects of a sustained 2-week course of the D2/3/4 receptor agonist pramipexole on
reward learning and used fMRI measures of expectation and prediction error to assess which of these three
mechanistic processes were responsible for the behavioural effects.
Methods: 40 healthy volunteers (Age: 18-43, 50% female) were randomly allocated to receive either two
weeks of pramipexole (titrated to 1mg/day) or placebo in a double-blind, between subject design.
Participants completed a probabilistic instrumental learning task, in which stimuli were associated with
either rewards or losses, before the pharmacological intervention and twice between days 12-15 of the
intervention (once with and once without fMRI). Both asymptotic choice accuracy, and a reinforcement
learning model, were used to assess reward learning.
Results: Behaviourally, pramipexole specifically increased choice accuracy in the reward condition, with no
effect in the loss condition. Pramipexole increased the BOLD response in the orbital frontal cortex during
the expectation of win trials but decreased the BOLD response to reward prediction errors in the
ventromedial prefrontal cortex. This pattern of results indicates that pramipexole enhances choice
accuracy by reducing the decay of estimated values during reward learning.
Conclusions: The D2-like receptor agonist pramipexole enhances reward learning by preserving learned
values. This is a plausible candidate mechanism for pramipexole’s observed anti-depressant effect. | en |
dc.description.sponsorship | Supported by the NIHR | en |
dc.description.uri | https://doi.org/10.1101/2022.01.14.22269287 | en |
dc.language.iso | en | en |
dc.subject | Depressive Disorders | en |
dc.title | Pramipexole Enhances Reward Learning by Preserving Value Estimates | en |
dc.type | Preprint | en |