In an Unspoken Voice: How the Body Releases Trauma and Restores Goodness

by Peter A. Levine

embedded within the lining of the gastrointestinal wall itself there is a massive plexus of nerves. This complex network of sensory, motor and interneurons (those nerve cells that connect between the sensory and motor neurons) integrates the digestive and eliminative organs so that they function coherently.m This intricate system has about the same number of neurons and white matter as does a cat’s brain. Because of this complexity, it has sometimes been called the second or enteric brain; the other three are the reptilian (instinctual), the paleomammalian (limbic/emotional) and the primate (enlarged, rational) neocortex. The enteric nervous system is our oldest brain, evolving hundreds of millions of years ago. It produces many beneficial hormones, including 95% of the serotonin in the body,n and thus is a primary natural medicine factory and warehouse for feel-good hormones.76 Amazingly, as much as 90% of the vagus nerve that connects our guts and brains is sensory! In other words, for every one motor nerve fibero that relays commands from the brain to the gut, nine sensory nerves send information about the state of the viscera to the brain. The sensory fibers in the vagus nerve pick up the complex telecommunications going on in the gut and relay them, first up to the (mid) brain stem and then to the thalamus. From there, these signals virtually influence the entire brain, and subliminal “decisions” are made that profoundly influence our actions. Many of our likes and di...