Dopamine Rewards Information-Seeking

Post by Elisa Guma

What's the science?

Humans have a desire to gain knowledge from their environment, often exhibited via information-seeking behaviours. Despite this being a central human behaviour, little is known about the biological mechanisms that control it. Previous studies have shown that information-seeking activates many of the brain’s reward pathways and dopamine-rich areas. This week in eLife, Vellani and colleagues seek to investigate the impact of dopamine, a neurotransmitter central to motivation and reward, on information-seeking behaviours.

How did they do it?

The authors performed a double-blind pharmacological intervention on 248 participants, who were recruited to perform an information-seeking task; one half of the group received L-DOPA to boost their dopamine levels, and the other half received a placebo. L-DOPA (or levodopa) is a precursor of dopamine which is converted to dopamine in the brain. It is typically used as a treatment for Parkinson’s disease symptoms.

Forty minutes following administration, participants completed a behavioural task consisting of four blocks (50 trials each) in which they had to invest in two of five possible stocks in a simulated stock market. On each trial, participants observed changes in the stock market and were instructed to bid for a chance to either know or remain ignorant about the value of their portfolio. Additionally, they had to decide how much they were willing to pay to secure their choice. The authors performed statistical modeling (linear mixed models) to investigate the effects of L-DOPA administration on information seeking behaviours, and whether or not the valence of the expectation influenced the participants’ decision to seek or avoid information. 

What did they find?

The authors observed that L-DOPA administration did not affect general information-seeking as there were no differences between groups in the number of trials in which participants chose to pay for or avoid information, or not to pay at all. Despite there being no differences in general information seeking, the authors found that information-seeking behaviour was modulated by the expected market outcome: participants were more likely to pay for information when the market was going up, in the hopes of receiving positive information, and more likely to pay to avoid information when the market was going down, in order to avoid negative news.

Interestingly, they found that the L-DOPA group was less affected by the expected valence of the information (whether it was a win or a loss). Specifically, participants in the placebo group desired to learn more information when the market was up vs. down, whereas the L-DOPA group’s desire to seek information was not affected by valence (i.e. they wanted to gain information regardless of whether it might be a win or a loss). Furthermore, when investigating the degree of market change, the L-DOPA group was willing to pay more for information the greater the gains or losses, whereas the placebo group was only willing to pay more for information the greater the gains, but not the losses. Finally, they found that the effects of valence observed in the L-DOPA group were not affected by the participant’s expectations about their outcomes (based on whether they believed their stocks to have increased or decreased).

What's the impact?

This study shows that dopamine plays a critical role in motivating information-seeking, even if it does not directly lead to a reward. By increasing dopamine levels via L-DOPA administration, participants sought out information both about potential wins and losses, contrary to the placebo group who was mostly interested in information about potential wins. Future studies may investigate whether patients with dopamine deficiencies exhibit abnormal patterns of information-seeking.

Vellani et al. A selective effect of dopamine on information-seeking. eLife (2020). Access to the original publication can be found here.