Risky Monkey Business Could Help Humans

January 31, 2006

Humans all too often compulsively take risks we shouldn't--blowing our life savings on a get-rich-quick scheme, taking drugs we know could kill us, and letting our waistline grow to heart-stopping proportions. To their surprise, Duke neurobiologists have found that monkeys also like to gamble, and the discovery could offer important insights into the neural machinery underlying risk-taking.

Michael Platt, assistant professor of neurobiology, and Allison McCoy, a third-year medical student, gave rhesus monkeys the chance to gamble on receiving squirts of a tasty juice. By choosing to glance at a "safe" or "risky" target light, the animals could choose whether to receive the same amount of juice each time or to gamble on receiving either a larger or smaller juice reward. As described in an article in a recent issue of Nature Neuroscience, they found that the monkeys overwhelmingly preferred to gamble by looking at the "risky" target--even though the average amount of juice was no larger than for the "safe" target.

"There was no rational reason why monkeys might prefer one of these options over the other because, according to the theory of expected value, they're identical," says Platt. The monkeys' predilection for gambling persisted even when the researchers reduced the reward from gambling or subjected the animals to a series of losses.

Especially significant about the findings, says Platt, is that the monkeys offer an animal model for risky behavior that can be studied in ways not possible in humans. The researchers used hair-thin recording microelectrodes to pinpoint one brain region involved in the circuitry governing risk-taking. Now, they can trace that circuitry to try to understand how it might go awry in compulsive behavior in humans. Someday, says Platt, studies could lead to treatments for such conditions as compulsive gambling, obsessive-compulsive disorder, and depression.