second brain

[mellowtigger]

I learned today that humans (perhaps all vertebrates) have a second brain in their body. It's diffuse, primitive, and limited to concerns of the gut, but it's definitely there. It's called the "enteric nervous system". It forms from the same early cells as the brain, it has more neurons than the spinal cord, and it can work independently.

"This is indeed the picture seen by developmental biologists. A clump of tissue called the neural crest forms early in embryogenesis, Dr. Gershon said. One section turns into the central nervous system. Another piece migrates to become the enteric nervous system. Only later are the two nervous systems connected via a cable called the vagus nerve."
- http://www.nytimes.com/1996/01/23/science/complex-and-hidden-brain-in-gut-makes-stomachaches-and-butterflies.html?pagewanted=all&src=pm

So it is literally a fragment of brain material that matures into a separate integration center, where it receiving incoming signals and reacts by directing appropriate responses. It's the area responsible for "stomach butterflies" during emotional stress. It is associated through neurotransmitters to our emotional state, and it may play a large part in emotional responses.

"The enteric nervous system uses more than 30 neurotransmitters, just like the brain, and in fact 95 percent of the body's serotonin is found in the bowels. Because antidepressant medications called selective serotonin reuptake inhibitors (SSRIs) increase serotonin levels, it's little wonder that meds meant to cause chemical changes in the mind often provoke GI issues as a side effect. Irritable bowel syndrome—which afflicts more than two million Americans—also arises in part from too much serotonin in our entrails, and could perhaps be regarded as a "mental illness" of the second brain."
- http://www.scientificamerican.com/article.cfm?id=gut-second-brain

I've been talking for years about emotion as a primary sensory issue for autistics (overwhelmed by bloodstream "emotional chemicals").

"I have argued previously that I think some emotions are actually sensations. I suspect that there are cells in the brain that "sense" chemicals in the blood and produce a perception of emotion the same way that we have cells that "sense" chemicals in the air we breathe and then produce a perception of odor."
- Terry Walker, 2005 February 06, ANI-L@LISTSERV.SYR.EDU, Autism Network International Listserv

This new information fits very well with my personal observations. It might eventually lead to hard evidence explaining why so many autistics use diet as a means of symptom and behavior control.