Visceral sensations arising from the digestive tract are an everyday occurrence and range from nonpainful sensations such as pressure or a sense of urgency to defecate to pain. Painful visceral sensations and hyperalgesia are a hallmark of disorders such as inflammatory bowel disease, irritable bowel disorder, and esophageal disease. However, little is known of the brain mechanisms underlying visceral sensations under normal and injured states, and how they differ from cutaneous sensations. Over the last decade, functional brain imaging has been adopted for the study of acute and chronic pain, typically arising from the skin. Imaging of visceral sensations poses several challenges due to the internal location of the site to be stimulated. The three studies presented in this chapter demonstrate that visceral imaging studies not only are feasible but also represent a valuable approach to understanding basic mechanisms of visceral sensations compared to cutaneous sensations under normal and pathological conditions.
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