Dopamine promotes instrumental motivation, but reduces reward-related vigour
- University of Oxford, United Kingdom
- University of Cambridge, United Kingdom
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)
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Author details
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
© 2020, Grogan et al.
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.
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Dopamine promotes instrumental motivation, but reduces reward-related vigour
eLife 9:e58321.
https://doi.org/10.7554/eLife.58321
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