As we navigate our daily lives, our choices are influenced by the information we gather. For example, how rewarding will it be to read this article, and is it worth the time and energy?
How our brains judge our willingness to gather information for a reward is unknown. Previous research suggested that antidepressants like SSRIs, which increase serotonin levels, reduce the perceived cost of physical actions. Now, a study published in the Journal of Neuroscience identifies the neurotransmitter serotonin for its role in motivating mental or cognitive work.
Scientists from the University of Berlin, the Max Planck Center, and the University of College London employed a card game to investigate how serotonin impacts our willingness to expend cognitive effort. Healthy participants were presented with cards facing down. As they flipped the cards over, subjects were rewarded by guessing whether there were more blue or yellow cards. However, each card flip came at the cost of points. Serotonin was manipulated with a week-long SSRI treatment, a single dose, or a placebo.
The results revealed that card players who received SSRI treatment had an increased inclination to flip cards, enhancing their chances of accurately guessing the dominant card color.
Using a computational model to explore the participants' decision-making, Michely et al. concluded that SSRI treatment altered the perception of the mental cost associated with information gathering. The participants in the placebo group behaved as if there was a higher cost of their sampling as they gathered more information. Treatment with single-dose or week-long SSRI treatments significantly increased the willingness to exert cognitive effort to maximize rewards.
The findings suggest that serotonin plays a crucial role in encoding the costs associated with mental work, offering valuable insights into how SSRIs can aid individuals with depression.
Serotonin is more than just an opponent of dopamine; it also affects our willingness to expend effort when faced with challenging experiences.
In a surprise twist that rewards those still reading this article, the treatment did not directly affect their response time, accuracy, or total earnings. Instead, the effect of SSRI on task earnings hovered just above the level needed for significance (p = 0.060). The researchers could not detect a measurable positive consequence to the increased information gathering displayed by the drug group. This might be due to the average serotonin production of the participants. Future experiments could explore this further with patient groups or alterations to the task.
The research's implications extend beyond depression. The non-linear increase in perceived costs could vary between individuals with different neuropsychological conditions, potentially leading to suboptimal decision-making. By determining how serotonin influences information-seeking behavior, this study takes a significant step forward in understanding the complexities of human motivation, decision-making processes, and how to write rewarding science news articles.
Sources: eLife, Journal of Neuroscience