The brain mechanisms that allow us to make choices and ultimately could be helpful in improving treatments for the millions of people who suffer from the effects of anxiety disorders have been revealed in a new study.
In the study, University of Colorado at Boulder psychology Professor Yuko Munakata and her research colleagues found that "neural inhibition," a process that occurs when one nerve cell suppresses activity in another, is a critical aspect in our ability to make choices.
"The breakthrough here is that this helps us clarify the question of what is happening in the brain when we make choices, like when we choose our words. Understanding more about how we make choices, how the brain is doing this and what the mechanisms are, could allow scientists to develop new treatments for things such as anxiety disorders," said Munakata.
Researchers have long struggled to determine why people with anxiety can be paralysed when it comes to decision-making involving many potential options.
Munakata believes the reason is that people with anxiety have decreased neural inhibition in their brain, which leads to difficulty making choices.
"A lot of the pieces have been there. What's new in this work is bringing all of this together to say here's how we can fit all of these pieces of information together in a coherent framework explaining why it's especially hard for people with anxiety to make decisions and why it links to neural inhibitors," she said.
In the study, they tested the idea that neural inhibition in the brain plays a big role in decision-making by creating a computer model of the brain called a neural network simulation.
"We found that if we increased the amount of inhibition in this simulated brain then our system got much better at making hard choices. If we decreased inhibition in the brain, then the simulation had much more trouble making choices," said Hannah Snyder, a psychology graduate student who worked with Munakata on the study.
Through their model they looked at the brain mechanisms involved when we choose words. They then tested the model's predictions on people by asking them to think of the first verb that comes to mind when they are presented with a noun.
"We know that making decisions, in this case choosing our words, taps into this left-front region of the brain, called the left ventrolateral prefrontal cortex. We wanted to figure out what is happening in that part of the brain that lets us make these choices. Our idea here, which we have shown through the word-choosing model, is that there's a fight between neurons in this area of the brain that lets us choose our words," said Munakata.
They then tested the model's predictions that more neural inhibition in the brain makes it easier to make choices by examining the effects of increased and decreased inhibition in people's brains.
They increased inhibition by using a drug called midazolam and found that people got much better at making hard choices.
It didn't affect other aspects of their thinking, but rather only the area of making choices.
They investigated the effects of decreased inhibition by looking at people with anxiety.
"We found that the worse their anxiety was, the worse they were at making decisions, and the activity in their left ventrolateral prefrontal cortex was less typical," said Munakata.
The study has been published in the latest edition of Proceedings of the National Academy of Sciences.