The largest collection or neurons in the body outside of the"bog" brain is the mesenteric plexus inside your abdomen.
It controls movement, the complex secretion of over 50 hormones. Of note:there are more serotonin receptors by five compared to the big brain, for which we use prozac (fluoxetine). In a lecture i once heard two years ago, irritable bowel syndrome was said to be "depression" of the small brain!
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