Feel-good transmitter levels in brain determine anger

September 19th, 2011 - 3:21 pm ICT by IANS  

London, Sep 19 (IANS) Fluctuating levels of serotonin, which may be triggered by abstaining from food or being stressed, affects brain regions that enable people to manage anger, a study shows.

Although reduced serotonin levels had been linked with aggression, this is the first study to show how this neuro-transmitter helps regulate behaviour in the brain and explains why some individuals are more aggressive.

Serotonin is a brain transmitter that conveys messages from one neuron to another. The feel-good chemical gives us self-confidence, a feeling of safety and security, and increases our appetite.

Molly Crockett, earlier doctoral student in clinical neuroscience at Cambridge University, co-authored the study, the journal Biological Psychiatry reports.

Crockett said: “We’ve known for decades that serotonin plays a key role in aggression, but it’s only very recently that we’ve had the technology to look into the brain and examine just how serotonin helps us regulate our emotional impulses.”

For the study, healthy volunteers’ serotonin levels were altered by manipulating their diet. On the serotonin depletion day, they were given a mixture of amino acids that lacked tryptophan, the building block for serotonin, according to a Cambridge statement.

On the placebo day, they were given the same mixture but with a normal amount of tryptophan. Researchers then scanned the volunteers’ brains using functional magnetic resonance imaging (FMRI).

They were able to measure how different brain regions reacted and communicated with one another when the volunteers viewed angry faces, as opposed to sad or neutral faces.

The findings suggest that when serotonin levels are low, it may be more difficult for a part of the brain to control emotional responses to anger generated in another.

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