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How does our brain function when we gamble?

September 7, 2017
Sridevi Sarma

Ever feel lucky? So lucky that you’re sure you can’t lose?

It’s not just a feeling. It’s an actual electromagnetic wave—between 36 and 50 hertz—that zips from one part of your brain to another. When it’s present, all things being equal, you might bet the house on your next hand of cards.

That’s a gross oversimplification of what a group of researchers, including Sridevi Sarma and her postdoctoral researcher, Pierre Sacré, discovered in a novel experiment that let them peek into subjects’ brains as they gambled. These weren’t Las Vegas high rollers, however. They were epilepsy patients at Cleveland Clinic, under observation of physicians who had implanted electrodes in their skulls to locate and eventually remove the minute regions that were responsible for seizures.

The patients had little to do during their weeks of observation, so were happy to participate in a gambling experiment. Sarma, associate director of the Institute for Computational Medicine, described the setup: Each patient played a form of the card game War against a computer, with a simulated card deck that had only the 2, 4, 6, 8, and 10 cards. Players had to bet either $5 or $20 (in imaginary money) that the card they had drawn would win over what the computer drew.

If a player drew a 2 or 4, the rational response would be to bet $5. If the player drew an 8 or 10, the rational response would be to bet $20. In economic terms, that’s what is known as the “expected reward” element of an individual’s decision-making—there’s a mathematical probability that supports the decision.

Harder for economists and psychologists to assess are the other two components of what drives a person’s actions: their propensity for risk-taking (although that can be observed over time) and their “bias”—that is, the internal emotional state of a person as he or she chooses.

“Nobody has put all of those together and tried to understand how they play a role while looking at the brain’s actions in milliseconds,” says Sarma. Other attempts involved functional MRI scans, which only measure blood flow and only in snapshots of a second or two apart. In this experiment, the researchers could detect electrical signals in milliseconds as they shot into the orbital frontal cortex.

And here’s where that 36 to 50 hertz wave, which they dubbed the “lucky wave,” first appeared. If players had been winning several hands in a row, they often generated that lucky wave. And when they did so, they’d bet the $20 not just when they drew an 8 or 10, but also a 6, a 4, and—despite the impossibility of winning—even a 2.

The results of that work were published last November in Scientific Reports. Now, Sarma’s drafting another paper that looks at similar activity throughout the brain, including such key emotional centers as the amygdala.

The gambling experiment is just one of many ways in which researchers are getting unprecedented looks at how the brain functions. Sarma is now working with a colleague who is interested in how learning takes place. “We all know the feeling of trying to understand something and not getting it until the light suddenly goes on and it makes sense,” she says. “We’re trying to see what’s happening in the brain as that happens.”

– Michael Blumfield

Category: Research
Associated Faculty: Sridevi V. Sarma

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