Role of the brain and sensory pathways in gastrointestinal sensory disorders in humans.

Several features of the irritable bowel syndrome (IBS) suggest involvement of the emotional limbic system in the brain. Abnormalities which upregulate afferent (sensory) signal intensity anywhere in this system, from the gastrointestinal tract to the brain, could induce hypersensitivity, leading to the pain and discomfort that characterise IBS and other functional disorders. Functional gastrointestinal disorders are likely to be heterogeneous given the complexity of the afferent system, and a number of different perturbations are possible. Intestinal hypersensitivity to pain and discomfort and associated reflex alterations in motility might explain the symptoms of functional bowel diseases.