Pungency and tingling: Sensations and mechanisms of trigeminal chemical sensitivity

Distinct from taste and olfaction, the trigeminal nerve is the third sensory pathway in the cranial sensory system that is sensitive to chemical stimuli. Trigeminal nerve endings in the nose and mouth contribute to flavor through the sensory modalities of touch, thermal sensation and pain. The best-characterized example of chemically induced trigeminal sensation is the pungency produced by hot peppers, the result of the activation of ion channels on pain-sensitive and thermally sensitive nerve fibers. Compounds commonly found in spices, food and beverages also elicit sensations other than pain. Menthol and other related compounds stimulate a subclass of thermal nerve endings to produce cooling. Yet other compounds, stimuli as diverse as CO, and fatty acids as well as some unsaturated alkylamides found in non-capsicum peppers and other plants, activate cooling-sensitive and tactile nerve endings. This particular combination of modalities gives rise to the novel tingling sensations associated with these stimuli.