How does the brain decide whether to risk a paycheck on the stock market or sock it away in the bank? That's one of the questions posed by the field of neuro-economics, which studies how the brain makes decisions.

According to new research by Mauricio Delgado, a neuroscientist at Rutgers University, our brains interpret losing money the same way they interpret pain. Delgado and his collaborators used functional magnetic resonance imaging, a technique that indirectly measures brain activity, to watch the brains of volunteers as they played a gambling game that resulted in either money loss or a painful shock. Volunteers rated both experiences as equally unpleasant, and in both cases, a part of the brain known as the striatum, which is involved in picking out the most rewarding objects or actions in our environment, became active. "Perhaps the way we learn about losing money is similar to how we learn to avoid shock," says Delgado, who presented the research this week at the Society for Neurosciences conference in Atlanta. According to Read Montague, a neuroscientist at Baylor University who also studies neuro-economics but was not involved in the current research, the findings show that older brain structures shared by all animals--not all of which deal with currency, obviously--can be used to make decisions about abstract symbols, such as money.

A second study found that certain gamblers release dopamine--a brain chemical linked to pleasurable sensations, such as food and sex or taking drugs--when gambling. Arne Moller (http://www.cfin.au.dk/index.php?menu=232), a neuroscientist at Aarhus University Hospital, in Denmark, used positron emission tomography (PET) to image dopamine concentrations in the brains of pathological gamblers as they played a gambling game. The findings could eventually help design specialized treatments for gamblers. "Gambling is like a parasite that learns to grow in our liver," says Montague. "It's a totally irrational behavior that takes advantage of the frailty of our decision-making systems."