Abstract
How negative emotion is produced in the brain is the crucial research question in psychosomatic medicine. Research on irritable bowel syndrome (IBS) provides basic and clinical keys to solve this question. Emotion consists of emotional states as bodily condition and conscious feeling. Emotions are typically elicited by a specific stimulus via afferent neurons. The stimulus is processed in the cortical (i.e. anterior cingulate) and subcortical (i.e. amygdala) structures. Thus skeletomotor and autonomic-endocrine control systems are activated. This changes activities of the peripheral organs. Altered activities of organs are conducted to the central nervous system as interoception via afferent neurons. Visceral stimulation therefore provides simple model to clarify the process of emotion. Colonic distention in normal individuals induces activation of the thalamus,, and prefrontal cortex with increased scores of abdominal pain and anxiety. In IBS patients, these changes are exaggerated. These changes seem to be dependent on personality, gene, and experience. Activities of amygdala, anterior cingulate cortex, and insula as well as regulatory substances like serotonin or corticotropin-releasing hormone may determine interoception and emotion. Further studies on interoception and emotion are warranted in the future.
