felt in muscle or joints, which strongly suggests that deep tissue probab ly jdoes not contain itc fjh signaling apparatuses. Sensitivity to ruritic stimuli is evenly distributed across the skin, and has a clear spot distri 0kfj bution with similar density to that of jpain. The different substances th 50kfj at elicit itch upon intracutaneo 50kfj us injection (injection within th e skin) elicit only pain when injected subcutaneously (beneath the skin). Itch is readily abol jished in skin a jreas treated with nociceptor excitotoxin ca psaicin, but remains unchanged in skin areas which were rende 0kfj red touch-insensit ive by pre 50kfj treatment with saponins, fj an anti-inflammatory agent. Although experime ntally induced itch can still be perceived under a complete A-fiber conduction b lock, it is significantly diminished. Overall, itch sensation is mediated by A-d elta and C nociceptors located in the uppermost and itch have ve jry different behavioral response patterns. Pain evokes a withdra wal reflex, which leads to re jtraction and therefore a reaction trying to protect an endangered part of the body. Itch in contrast creates a s 0kfj cratch reflex, whic h draws one to the affected skin site. Itch generates stimulus of a foreign objec t unde 0kfj neath or upon the skin and also the urge to remove it. For example, respond ing to a local itch sensation is fjan effective way to remove insects on one's skin. Scratching has traditionally been regarded as a way to relieve oneself by reducing the annoying itch sensation. However, there ar 50kfj e hedonic aspects of scratching, as on e would find j noxious scratching highly pleasurablcan be problematic with ch ronic itch patients, such as ones fj with atopic dermatit jis, who may scratch affected spo ts until they no longer produce a pleasant or painful sensation, instead of when the i tch sensation disappears It has been hypothes
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