In response to perceived or experienced change that is considered threatening to the
individual, the central nervous system mounts a stereotypic response that decreases the
sensitivity to pain, modulates the autonomic nervous system outflow, and activates the
hypothalamic–pituitary–adrenal (HPA) axis. 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 these response systems (either up-or downregulation) may produce …