# Bidirectional modulation of reward-guided decision making by dopamine

## TL;DR

This study shows that dopamine affects how people weigh different aspects of rewards when making decisions, without changing the decision strategy itself.

## Contribution

The study reveals that dopamine modulates the influence of reward attributes on choices in a bidirectional manner, independent of decision strategies.

## Key findings

- Amisulpride reduced the influence of reward magnitude and probability on choices.
- L-DOPA increased the influence of reward magnitude and probability on choices.
- Dopamine manipulations did not alter statistically optimal decision-making behavior.

## Abstract

The neuromodulator dopamine is known to play a key role in reward-guided decision making, where choice options are often characterized by multiple attributes. Different decision strategies can be used to merge these choice attributes with personal preferences (e.g., risk preferences) and integrate them into a single subjective value. While the influence of dopamine on risk preferences has been investigated, it is unknown whether dopamine is also involved in arbitrating between decision strategies.

In the present study, we investigate the effects of pharmacological dopamine manipulations on arbitrating between different decision strategies in a healthy sample.

31 healthy male participants performed a reward-guided decision-making task under the influence of the dopamine D2/D3-receptor antagonist amisulpride (400 mg), the dopamine precursor L-DOPA (100 mg L-DOPA + 25 mg cardidopa), or placebo in a double-blind within-subject design. The effect of dopamine on reward-guided decisions and decision strategies was analyzed using hierarchical implementations of regressions and Bayesian models.

Notably, we observed that the dopaminergic interventions shifted the (overall) weighting of option attributes without changing how option attributes are integrated into a subjective value (decision strategy). These effects were bidirectional: Amisulpride reduced whereas L-DOPA increased the degree to which choices were influenced by both reward magnitude and reward probability. These effects occurred in the absence of changes in statistically optimal behavior.

Together, our data provide evidence for a role of dopamine in controlling the influence of value parameters on choice irrespective of decision strategies.

The online version contains supplementary material available at 10.1007/s00213-025-06816-9.