Communication between the GI tract and the CNS occurs via the neuronal,endocrine, and immunological pathways through a) the production of neurotransmitters, b) the tryptophan metabolism, c) the modulation of the immunological activity in the CNS and the SNE, d) production of short chain fatty acids, e) the production of intestinal hormones, and f) the production of branched chain amino acids. CLICK TO REVIEW