Qualitative effects in nasal trigeminal chemoreception.

Olfaction and nasal trigeminal chemoreception together convey an impression of the physical and chemical qualities of inspired air. "Nasal pungency" refers to the nasal trigeminal impact of inhaled air pollutants as well as spicy foods and selected medicaments. Such diverse sensations as cooling, numbness, tingling, itching, burning, and stinging are all conveyed by the trigeminal system yet are successfully differentiated in psychophysical testing, with or without concomitant olfactory information. Here we briefly review the neurobiological and psychophysical evidence for qualitative specificity in the nasal trigeminal system.