This striking image shows a polarized light micrograph of crystals of serotonin, which acts as a neurotransmitter and assists in relaying messages from one area of the brain to another. Almost all of the approximately 40 million cells contained in the brain are affected either directly or indirectly by serotonin.
Now new findings (subscription required) published this week in Biological Psychiatry shows fluctuating levels of the brain chemical, which can occur when you're stressed or hungry, may make it more difficult for the brain to control emotional responses to anger. Reuters reports:
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. On the placebo day, they were given the same mixture but with a normal amount of tryptophan.
The researchers then scanned the volunteers' brains using functional magnetic resonance imaging (fMRI) as they viewed faces with angry, sad, and neutral expressions. They were able to measure how different brain regions reacted and communicated with one another when the volunteers saw angry faces, as opposed to sad or neutral faces.
The results showed that low brain serotonin made communications between specific brain regions of the emotional limbic system of the brain -- a structure called the amygdala -- and the frontal lobes weaker compared to when serotonin levels are normal.
Using a personality questionnaire, the researchers also analysed which of the volunteers had a natural tendency to behave aggressively. In these people, the communications between the amygdala and the prefrontal cortex was even weaker following serotonin depletion.
Researchers hope their findings will help in improving methods for diagnosing and treating a range of psychiatric disorders.
Photo by Wellcome Images