How monkeys decide to explore new options

WASHINGTON - Researchers at Duke University Medical Center have used brain scans in monkeys to predict when monkeys decide if they want to switch from exploiting a known resource to exploring newer options.

Such a trade-off is easy for many, but not for those with conditions such as Alzheimer’s disease or obsessive-compulsive disorder who are trapped in simple routines.

“Humans aren’t the only animals who wonder if the grass is greener elsewhere, but it’s hard to abandon what we know in hopes of finding something better,” said Dr. John Pearson.

“Studies like this one help reveal how the brain weighs costs and benefits in making that kind of decision. We suspect that such a fundamental question engages many areas of the brain, but this is one of the first studies to show how individual neurons can carry signals for these kinds of strategic decisions,” he added.

The researchers analysed how nerve cells fired in a part of the brain known as the posterior cingulate cortex as the monkeys were offered a selection of rewards.

Generally, these neurons fired more strongly when monkeys decided to explore new alternatives.

The monkeys started with four rewards to choose from, each a 200 microliter cup of juice.

Later, the four targets began to slowly change in value, becoming larger or smaller. The monkeys were free to explore the other targets or stay with the initial target, whose value they knew for certain.

The animals had to select an option to learn its current value and integrate this information with their knowledge of the chances of getting more juice at a different target.

The researcher studied individual neurons and were able to predict which strategy the monkey would employ.

“These data are interesting from a human health perspective, because the posterior cingulate cortex is the most metabolically active part of the brain when we are daydreaming or thinking to ourselves, and it is also one of the first parts of the brain to show damage in Alzheimer’s disease,” said Dr. Michael Platt.

“People with Alzheimer’s become set in their ways and don’t explore as much, which may be because this part of the brain is damaged. Likewise, in people with obsessive-compulsive disorder, they can become fixed on certain activities or patterns of activity and can’t disengage from them, which may also relate to changes in this part of the brain that renders them mentally unable to switch gears between exploring and exploiting,” he added.

Such brain functions could be crucial to the flexible adaptation of strategy in response to changing environments, said Pearson.

The study has been published in the latest issue of Current Biology. (ANI)