Brain Sees Reward Before Risk

TUESDAY, Aug. 1 (HealthDay News) -- California researchers say they have pinpointed the area of the brain that governs gambling behaviors.

By using functional magnetic resonance imaging (fMRI), scientists at the California Institute of Technology, in Pasadena, confirmed that the "gambling" parts of the brain lie in the subcortical region, and there are pathways in the brain that weigh risk and reward.

"We wanted to know what happens in the brain when one is faced with a probable reward and risk," said study co-author Kerstin Preuschoff, a doctoral student at the institute.

Preuschoff said that by understanding these pathways, scientists may be able to develop ways to treat those with impaired decision-making skills, such as gamblers, people with bipolar disorder, and schizophrenics.

The findings were expected to be published in the Aug. 3 issue of Neuron.

The study included 19 healthy adults between the ages of 18 and 30. Nine were female. All had no history of mental illness or gambling addiction.

Each participant was given an initial endowment of $25. While they were being scanned with fMRI -- which produces images of blood flow in the brain -- they were asked to bet $1 on whether or not the first or second card from a deck of 10 would be higher.

"They had to first place the bet without seeing the cards," explained Preuschoff. "Then, the expectation changes when they see the first card."

The researchers focused on the period after the study volunteers saw the first card, but before they'd seen the second card. It was during this period that they had enough information to more accurately assess the risk of the bet that they'd already placed, and to anticipate the reward of winning if they felt their card was a good one.

Interestingly, the study participants focused for a second solely on the anticipated reward.

"The risk signal had a delayed onset," Preuschoff said.

"It turns out that anticipation of reward seems to kick in before the brain regions associated with assessing risk do," said Dr. Eric Hollander, professor and chairman of psychiatry at Mount Sinai School of Medicine in New York City.

The regions of the brain activated by this risk vs. reward behavior are areas that are controlled by the neurotransmitter dopamine. Dopamine helps govern movement, emotional responses and the ability to feel pleasure and pain. Many addictive substances alter the amount of dopamine in the brain.

"This study reinforces the idea that these dopamine systems are involved in anticipated reward and in assessment of risk," said Hollander.

Preuschoff said it's likely that people with mental illnesses, such as bipolar disorder or pathological gambling, would have subtle differences in these areas when scanned. He said such people often underestimate the actual risk, or may have an impaired ability to assess risk.

"If we can understand the pathway, maybe we can help develop methods to fix it," said Preuschoff.