Abstract
In everyday life, we encounter situations that require tradeoffs between potential rewards and associated costs, such as time and (physical) effort. The literature indicates a prominent role for dopamine in discounting of both delay and effort, with mixed findings for delay discounting in humans. Moreover, the reciprocal antagonistic interaction between dopaminergic and cholinergic transmission in the striatum suggests a potential opponent role of acetylcholine in these processes. We found opposing effects of dopamine D2 (haloperidol) and acetylcholine M1 receptor (biperiden) antagonism on specific components of effort-based decision making in healthy humans: haloperidol decreased, whereas biperiden increased the willingness to exert physical effort. In contrast, delay discounting was reduced under haloperidol, but not affected by biperiden. Together, our data suggest that dopamine, acting at D2 receptors, modulates both effort and delay discounting, while acetylcholine, acting at M1 receptors, appears to exert a more specific influence on effort discounting only.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
We have revised the introduction and discussion to avoid overgeneralizations regarding the roles of dopamine and acetylcholine in cost-benefit decision making. We now also characterize the relationship between both neurotransmitter systems more cautiously, limiting contrasting effects to specific components of effort-based behaviour. Further, we have incorporated additional analyses to control for potential confounding factors, such as fatigue and session effects. Finally, we have expanded the methods section to provide a more comprehensive explanation of our analysis approach.
