A key regulator of decision-making identified in the brain

Researchers at Washington University School of Medicine in St. Louis have new insights into what goes through people’s heads when they make decisions to gain information about the future.

Scientists have identified a set of mental rules that govern decision-making regarding physical rewards (for example, food or money) and cognitive rewards, such as the joy felt by accessing the information sought.

They also identified the part of the brain that regulates this type of decision-making. The process occurs in the lateral habenula, an ancient brain structure shared by species as distantly related as humans and fish. The study is published in Natural neuroscience.

The findings not only offer insight into the body’s most mysterious organ, but have the potential to help people grappling with difficult choices, whether due to the inherent complexity of some decisions, such as whether to pass a genetic test that may return unwanted information, or due to mental illnesses that affect the ability to make decisions, such as obsessive-compulsive disorder (OCD), anxiety and depression.

“Identifying the circuits involved in assigning value to cognitive rewards, like information about the future, is really important, because this type of valuation is often what breaks down in mental disorders,” said the lead author. Ilya Monosov, professor of neuroscience at the University of Washington. .

“If we can understand exactly what part of the decision-making process is malfunctioning in an individual, we may be able to target precisely that aspect of the process and treat certain mental illnesses more effectively.”

Choosing between two options often requires weighing the values ​​of several factors and making trade-offs between them. Some of these factors are concrete and practical. But there are also intangible factors that can be powerful motivations for choosing one option over another, such as the desire to satisfy curiosity and obtain information.

Some information, of course, has practical value, such as advance warning of an impending hurricane. But experiments have shown that humans and animals enjoy getting information even if they can’t turn it into something useful.

“Take, for example, a student who takes a final exam and then wants to know the results immediately,” said co-first author Yang-Yang Feng, MD/Ph.D. student who designed and directed the study’s experiments with human participants. “Finding out your score today versus finding out in a week won’t change the results or give you any benefit. But some people want to know so much that they’ll pay to find out sooner. That’s what we calls non-instrumental information seeking., trying to obtain information for its own sake.”

Historically, the drive to obtain practical rewards, such as money or food, and the drive to obtain information have been studied as separate phenomena. This division is artificial and oversimplifies the choices people make in the real world, researchers say.

Feng and co-first author Ethan Bromberg-Martin, a senior scientist in Monosov’s lab, designed experiments that required participants to make trade-offs between rewards and non-instrumental information, to make a final decision.

Study participants had two options to choose from, each giving them a chance to get a few cents. The amount of money they could win and the likelihood of winning it varied. Some of the options came with the promise of knowing the outcome early on, before the real money arrived. In separate experiments, monkeys were presented with similar choices, with juice as a reward instead of money.

“By analyzing the trade-offs individuals make, we were able to develop some of the rules that individuals use to decide how much they are willing to pay for information,” Bromberg-Martin said. “These rules have become widespread between humans and animals, suggesting that this abstract value may be conserved through evolution.”

One of the key principles discovered is that individuals seek information largely to resolve uncertainty. The more uncertainty there is, the more they are willing to pay for information about it. Intuitively, this makes sense. You would probably be willing to pay more to know the outcome of a $100 bet than a $1 bet, especially if you could get the information as soon as possible. These and other principles form a logical framework that the brain uses to make choices.

But sometimes the system malfunctions.

“Some people with OCD exhibit what are called checking behaviors, where they go back and check the same thing over and over again,” Monosov said. “This is aberrant information-seeking behavior, primarily due to poor processing of uncertainty.”

In this study, the team discovered that decision-making algorithms are implemented through a neurological circuit that culminates in the lateral habenula, a tiny structure located deep in the brain. The lateral habenula is a major regulator of dopamine and has been associated with mental illnesses including depression, anxiety, and OCD.

The team is working on using tasks requiring participants to make choices, similar to those in this study, to classify people with OCD into subtypes that match how their brains process uncertainty. This would be a step towards more targeted therapies.

“A person may be fine in some ways, but their processing of uncertainty is disrupted in a specific way,” Monosov said. “Rather than saying that a person has a generalized mental disorder such as OCD, we could say that their processing of uncertainty is interrupted in this specific way, and here’s how we can modulate it. That’s a step towards more personalized medicine for mental illnesses.”