Itch - Sensations Associated With Scratching

Sensations Associated With Scratching

Pain and itch have very different behavioral response patterns. Pain evokes a withdrawal reflex which leads to retraction and therefore a reaction trying to protect an endangered part of the body. Itch creates a scratch reflex which draws one to the affected skin site. For example, responding to a local itch sensation is an effective way to remove insects on the skin. Scratching has traditionally been regarded as a way to relieve oneself by reducing the annoying itch sensation. However there are hedonic aspects of scratching as one would find noxious scratching highly pleasurable. This can be problematic with chronic itch patients, such as ones with atopic dermatitis, who may scratch affected spots until it no longer produces a pleasant or painful sensation instead of when the itch sensation disappears. It has been hypothesized that motivational aspects of scratching include the frontal brain areas of reward and decision making. These aspects might therefore contribute to the compulsive nature of itch and scratching.