 Once stimulated, usually by histamine within the body, a signal is sent through the peripheral nervous system to the brain (thalamus), where the information is processed and the command for the bodily response is issued.Itch can also originate as a result of damage to the nervous system (central or peripheral) or in response to the presence of excess opioids.Because of the scarcity of research available on mitempfindung, there is no widely accepted theory on how the referral of sensation is manifested.