Take a look at this book, he Second Brain : The Scientific Basis of Gut Instinct and a Groundbreaking New Understanding of Nervous Disorders of the Stomach and

Take a look at this book, he Second Brain : The Scientific Basis of Gut Instinct and a Groundbreaking New Understanding of Nervous Disorders of the Stomach and Intestines: http://amzn.to/2dmlrM4 http://amzn.to/2dmlrM4 It touches on how the enteric nervous system has similar structures to the brain and also produces neurochemicals. Interesting perspective.