Study Examines Brain's Risk Center

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From NPR News, this is ALL THINGS CONSIDERED. I'm Michele Norris.

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For most of us, the prospect of losing money is scary. Scientists say that's because somewhere in our brains is a little voice urging caution when money is at stake. Now, researchers think they've found out where that voice lives.

NPR's Jon Hamilton has the story.

JON HAMILTON: There's an unusual woman in California who takes part in research studies from time to time. Scientists refer to her by her initials, S.M.

Professor COLIN CAMERER (Behavioral Economics, California Institute of Technology): She's quite normal and kind of a cheerful person. She sort of likes being involved in the studies.

HAMILTON: Colin Camerer studies behavioral economics at Caltech. He says if you look closely, there are hints that S.M. isn't quite like other people.

Prof. CAMERER: Most people, if you stand about three feet away from them, they feel very comfortable. If you come one-and-a-half feet away, they kind of freak out. But S.M. doesn't mind if you come walk right up to her.

HAMILTON: That's because a part of S.M.'s brain called the amygdala has been damaged by a rare disease. Camerer says in most people, one of the jobs of the amygdala is to tell us not to let someone stand too close.

Prof. CAMERER: It's sort of an early warning system about impending threat.

HAMILTON: Camerer and his colleagues wanted to know if the amygdala provided warnings about financial threats, as well as physical ones. So they had S.M., a second woman with damage to her amygdala and several people with normal brains play a gambling game. Camerer says the people with normal brains were reluctant to risk money even when the odds were in their favor, but it was a different story for both women with amygdala damage. And Camerer says S.M. was just plain reckless.

Prof. CAMERER: She really didn't mind losing dollars compared to winning dollars, almost like loss-seeking or let's say very loss-tolerant.

HAMILTON: Camerer says the results offer strong evidence that the amygdala really is the source of that little voice that urges financial caution.

Prof. CAMERER: The amygdala is broadcasting kind of a fear or vigilance signal, like be careful, be careful, don't take this gamble, or take this gamble only if the amount we can win is really great.

HAMILTON: Unless you're a compulsive gambler, of course. Camerer suspects that if you could compare the brains of these extreme financial risk takers with the brains of people who never gamble, you would find a difference in the amygdala. The research appears in the journal Proceedings of the National Academy of Sciences.

Jon Hamilton, NPR News.

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