A study in the May issue of Neuron identifies reward circuits in the brain that are involved in the experience of monetary gains and losses. The results suggest that the same circuits activated by cocaine and nicotine in habitual users may be involved in compulsive gambling.Hans Breiter and colleagues at the Massachusetts General Hospital's NMR-Center imaged the brain activity of 12 people who played games of chance in which they could win or lose money.
Given $50 to start, the subjects watched a simplified wheel of fortune in action. On any given trial, a subject might see a "good" spinner that could land on +$10, +$2.50 or $0, an "intermediate" spinner, or a "bad" spinner that could land on $0, -$1.50 or -$6. Brain activity was monitored both while the subjects were waiting for a spinner to stop and after they saw the amount of money they had won.
While waiting for the spinner to stop, certain brain areas known to be activated in other rewarding situations were more active for the "good" than the "bad" spinner.
In contrast, when anticipating loss from the "bad" spinner, the amygdala -- a part of the brain involved in fearful emotions -- became increasingly active.
When the spinner landed on a good outcome, the responses in some of these reward-related regions was greater for larger payoffs.
These results can all be viewed in light of psychological research on how emotions are involved in gambles and chance. We have expectations and fears based on the likelihood of wins and losses, and our feelings about money actually won or lost in a gamble are shaped by these expectations. This work describes the brain responses in these different scenarios.
A compelling feature of these results is the finding that these brain regions overlap those implicated in expecting and receiving pleasant or unpleasant tastes and touches, and even cocaine infusion in habitual users.
These parts of the brain receive and deliver dopamine, which is thought to be a key to reward and addiction. The researchers conclude that dysfunction in these same reward circuits could be implicated in compulsive gambling.
Breiter and colleagues hope to unravel the cognitive, emotional and motivational mechanisms involved in making or losing money.
"We can begin to dissect the systems that process reward in humans," says Breiter. But it seems there's still no medical substitute for a positive bank balance."
(Reference: Neuron Volume 30 Number 2 May 2001.)
[Contact: Hans C. Breiter]
24-May-2001
