Figure 1.

A systems biology model for the brain-gut–microbiome interactions in mammals. The interconnected structural networks of the central nervous system influence via the autonomous nervous system to alter microbiota composition and function indirectly by regulating the microbial environment in the gut. The brain communicates with the gut microbiota indirectly through gut-derived molecules via afferent vagal and spinal nerve endings, or directly through microbe-generated signals. Alterations in these bidirectional interactions in response to perturbations like diet, medication, infections, and stress can alter the stability and behavior of this system resulting in brain-gut disorders.