How Humans Make Up Their Minds: Brain Region Associated with Decisions Discovered

How do humans make up their minds? It turns out that one of the smallest parts of the brain is critical for decision-making. Now, scientists are taking a closer look at this area of the brain in order to learn a bit more about how people decide between two options.

"These findings clarify the brain processes involved in the important decisions that we make on a daily basis, from choosing between job offers to deciding which house or car to buy," said Stan Floresco, one of the researchers, in a news release. "It also suggests that the scientific community has misunderstood the true functioning of this mysterious, but important, region of the brain."

In order to examine the decision-making process, the researchers trained rats to choose between a consistent small reward or a potentially larger reward that appeared sporadically. Like humans, the rats tended to choose the larger rewards when costs were low, but preferred smaller rewards when risks were higher.

Yet this decision-making process changed when scientists turned off the lateral habenula. This part of the brain has previously been associated with improving depressive symptoms in humans when it's deactivated. When the researchers turned it off in rats, though, the rodents chose an option at random and no longer seemed to be able to choose the best option for them in any given situation.

"Deep brain stimulation--which is thought to inactivate the lateral habenula--has been reported to improve depressive symptoms in humans," said Floresco in a news release. "But our findings suggest these improvements may not be because patients feel happier. They may simply no longer care as much about what is making them feel depressed."

The findings reveal a little bit more about the decision-making process. Understanding it is crucial for future studies, as well. Many psychiatric disorders, such as schizophrenia, stimulant abuse and depression, are associated with impairments in these processes. That means learning as much as possible about what helps people make up their minds is a large part of creating better treatments for the future.

The findings are published in the journal Nature Neuroscience.