Scientists from the University of Illinois at Chicago have discovered that alcohol intoxication reduces communication between two areas of the brain that work together to interpret social signals such as facial expressions.
Previous research had shown that alcohol suppresses activity in the amygdala, the area of the brain responsible for perceiving social cues. "Because emotional processing involves both the amygdala and areas of the brain located in the prefrontal cortex responsible for cognition and modulation of behavior, we wanted to see if there were any alterations in the functional connectivity or communication between these two brain regions that might underlie alcohol's effects," explained researcher K. Luan Phan.
The participants were 12 heavy social drinkers (10 men, two women) with an average age of 23. They were given a beverage containing either a high dose of alcohol (16 percent) or a placebo. They then had an fMRI scan as they tried to match photographs of faces with the same expression. They were shown three faces on a screen - one at the top and two at the bottom - and were asked to pick the face on the bottom showing the same emotion as the one on top. The faces were angry, fearful, happy or neutral.
When participants processed images of angry, fearful and happy faces, alcohol reduced the coupling between the amygdala and the orbitofrontal cortex, an area of the prefrontal cortex implicated in socio-emotional information processing and decision-making.
The researchers also noticed that alcohol reduced the reaction in the amygdala to threat signals - angry or fearful faces. "The amygdala and the prefrontal cortex have a dynamic, interactive relationship. How the amygdala and prefrontal cortex interact enables us to accurately appraise our environment and modulate our reactions to it," Phan explained. "If these two areas are uncoupled, as they are during acute alcohol intoxication, then our ability to assess and appropriately respond to the non-verbal message conveyed on the faces of others may be impaired. This research gives us a much better idea of what is going on in the brain that leads to some of the maladaptive behaviors we see in alcohol intoxication including social disinhibition, aggression and social withdrawal."
Discuss this article in our forum
Older Women And Alcohol: Out of Mind And Out of Sight
Sex and Alcohol
Sex, alcohol and consent make blurry bedfellows...
Female serotonin system especially vulnerable to alcohol
Source: University of Illinois at Chicago