Working with a dozen healthy participants who drink socially, research fellow Jodi Gilman, working with senior author Daniel Hommer, MD, at the National Institutes on Alcohol Abuse and Alcoholism, used functional magnetic resonance imaging (fMRI) 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. (Previous studies have shown that expressions of fear signal a threatening situation and activate specific brain regions.)
The same group of participants received both alcohol and placebo, on two separate days.
Comparing brain activity, Gilman’s team found that when participants received the placebo infusion, fearful facial expressions spurred greater activity than neutral expressions in the amygdala, insula, and parahippocampal gyrus—brain regions involved in fear and avoidance—as well as in the brain’s visual system. However, these regions showed no increased brain activity when the participants were intoxicated.
In addition, alcohol activated striatal areas of the brain that are important components of the reward system. 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. Gilman’s team found that the level of striatal activation was associated with how intoxicated the participants reported feeling. These striatal responses help account for the stimulating and addictive properties of alcohol.
Does alcohol have a similar suppressive effect in reaction to a happy face? Or does it amplify our emotional response to happy smiling people?
A hobbled ability to detect threats can get one into trouble.
“The key finding of this study is that after alcohol exposure, threat-detecting brain circuits can’t tell the difference between a threatening and non-threatening social stimulus,” said Marina Wolf, PhD, at Rosalind Franklin University of Medicine and Science, who was unaffiliated with the study. “At one end of the spectrum, less anxiety might enable us to approach a new person at a party. But at the other end of the spectrum, we may fail to avoid an argument or a fight. By showing that alcohol exerts this effect in normal volunteers by acting on specific brain circuits, these study results make it harder for someone to believe that risky decision-making after alcohol ‘doesn’t apply to me’,” Wolf said.
Do some people have minds that naturally fail to identify threatening or fearful or angry faces? Can one lack this ability yet still have the ability to identify happy faces or faces that communicate other emotional states? My guess is that some of these facial expression reading abilities vary separately from each other.
|Share |||Randall Parker, 2008 May 04 11:42 AM Brain Addiction|