Spinal and supraspinal modulation of visceral sensation

In response to perceived or experienced change, which is considered threatening to the individual, the central nervous system mounts a stereotypic response which decreases the sensitivity to somatic pain, modulates autonomic nervous system outflow, and activates the hypothalamic-pituitary-adrenal axis. Recent experimental evidence obtained in rats suggests that this response can be associated with an increase in visceral sensitivity. This response of the "emotional motor system" may or may not be associated with the conscious experience of feelings of fear or anxiety. Alterations in some of these response systems (antinociception, vigilance) may be responsible for the characteristic visceral hypersensitivity often seen in patients with functional gastrointestinal disorders.