Jodi Gilman and Dr. Daniel Hommer at the National Institutes on Alcohol Abuse and Alcoholism used functional magnetic resonance imaging to study activity in emotion-processing brain regions during alcohol exposure. Over two 45-minute periods, the study participants received either alcohol or a saline solution intravenously and were shown images of fearful facial expressions.

The study, published in The Journal of Neuroscience, showed alcohol affects the brain by decreasing sensitivity to threats and increasing activity in brain regions involved in reward.

The same group of participants received both alcohol and placebo, on two separate days. Gilman's team found brain activity in participants receiving the placebo was spurred by the fearful expressions. However, these regions showed no increased brain activity when the participants were infused with alcohol.

In addition, those who became intoxicated activated striatal areas of the brain key to feelings of reward. This confirms previous findings and supports the idea that activation of the brain's reward system is a common feature of all drugs of abuse, the researchers said.