When and how should we study colonic motility?

The colon has an autonomic activity owing to the concerted actions of the interstitial cells of Cajal, the enteric nervous system (especially myentric plexus and submucosal plexus), and smooth muscle cells. Changes in colonic motility are perceived centrally and can affect the neurons in the central nervous system. Conversely, the central nervous system can affect colonic motility via hormonal and neural signals. These reciprocal relations between the brain and the colon are known as the brain-gut interactions. Normal colonic motility consists of segmental contractions, propulsion, and high-amplitude propagating contractions. Physical stimulation of the internal lumen of the colon causes a reflex action and gastrointestinal perception. This activity comprises the peristaltic reflex, colo-colonic inhibitory reflex, and colonic perception. Several methods have been developed for observing colonic motility in the human body. Barostat and gastrointestinal manometry are suitable for the analysis of the gastrointestinal wall motion, while the analysis of gastrointestinal transit can be performed using radioisotopes, radiopaque markers, and the hydrogen breath test. There are various diseases based on the pathology and/or pathophysiology of colonic motility. They are chronic intestinal pseudo-obstruction, megacolon, colonic inertia, Hirschsprung's disease, colonic diverticula, colonic motility disorders due to systemic diseases, functional constipation, functional diarrhea, and irritable bowel syndrome. Thus, the physiology of colonic motility and pathology are gradually being elucidated. Functional investigations of motility in order to clarify pathological colonic motility are progressing. The ultimate goal is a treatment that is highly rational and highly effective in colonic motility disorders. It is important to identify the key molecules and disordered levels in the brain, autonomic nervous system, or enteric nervous system. A new technique is therefore required to address the whole understanding of disorders of colonic motility.