Dopamine promotes instrumental motivation, but reduces reward-related vigour

Abstract
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Abstract

We can be motivated when reward depends on performance, or merely by the prospect of a guaranteed reward. Performance-dependent (contingent) reward is instrumental, relying on an internal action-outcome model, whereas motivation by guaranteed reward may minimise opportunity cost in reward-rich environments. Competing theories propose that each type of motivation should be dependent on dopaminergic activity. We contrasted these two types of motivation with a rewarded saccade task, in patients with Parkinson’s disease (PD). When PD patients were ON dopamine, they had greater response vigour (peak saccadic velocity residuals) for contingent rewards, whereas when PD patients were OFF medication, they had greater vigour for guaranteed rewards. These results support the view that reward expectation and contingency drive distinct motivational processes, and can be dissociated by manipulating dopaminergic activity. We posit that dopamine promotes goal-directed motivation, but dampens reward-driven vigour, contradictory to the prediction that increased tonic dopamine amplifies reward expectation

Data availability

Anonymised data are available on OSF (https://osf.io/2k6x3)

The following data sets were generated

1. Grogan JP
2. Sandhu TR
3. Hu MT
4. Manohar SG
(2020) Contingent Motivation in PD
OSF, 2k6x3.

https://osf.io/2k6x3

Article and author information

Author details

John P Grogan

Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom

For correspondence
john.grogan@ndcn.ox.ac.uk

Competing interests
No competing interests declared.

"This ORCID iD identifies the author of this article:" 0000-0002-0463-8904
Timothy R Sandhu

Department of Psychology, University of Cambridge, Cambridge, United Kingdom

Competing interests
No competing interests declared.
Michele T Hu

Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom

Competing interests
Michele T Hu, MTH is a consultant advisor to the Roche Prodromal Advisory, Biogen Digital Advisory Board, Evidera, and CuraSen Therapeutics, Inc..
Sanjay G Manohar

Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom

Competing interests
No competing interests declared.

"This ORCID iD identifies the author of this article:" 0000-0003-0735-4349

Funding

MRC (MR/P00878X)

Sanjay G Manohar

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

Ethics

Human subjects: Ethical approval was granted by the South Central Oxford A REC (18/SC/0448). All participants gave written informed consent.

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.