Ask anyone down the pub what happens when you drink and they'll have the answer: you cheer up and loosen up. Yet until now no one has explored what happens in the brain during intoxication.
Jodi Gilman and her colleagues at the US National Institute on Alcohol Abuse and Alcoholism in Bethesda, Maryland, used MRI to observe the brain activity of 12 healthy "social drinkers" both when sober and after they had been given alcohol intravenously and their blood alcohol levels had reached nearly 0.08 grams of alcohol per 100 millilitres of blood - the legal limit for driving in the UK and the US. In both conditions they were shown pictures of either frightened or neutral faces.
The researchers found that booze completely changed the way the brain reacted to the images. Without alcohol, the amygdala - which is involved in processing emotional reactions - lit up in response to the frightened faces, but with alcohol, it was less active, reacting equally to neutral and fearful faces. This may help explain why drunkenness makes people both more outgoing and more aggressive: it impairs the amygdala's ability to detect threats (The Journal of Neuroscience, DOI: 10.1523/jneurosci.0086-08.2008).
The researchers also confirmed that alcohol activates reward circuits, such as the nucleus accumbens, just as other drugs of abuse do - resulting in pleasurable feelings.
Drugs and Alcohol - Learn more in our comprehensive special report.
The Human Brain - With one hundred billion nerve cells, the complexity is mind-boggling. Learn more in our cutting edge special report.
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