ABSTRACT
The gustatory system is responsible for four basic taste experiences: salty, sweet, sour, and bitter. A fifth quality, called umami, has been postulated to describe the taste of monosodium glutamate and related compounds (Rolls et al., 1998). However, these taste bud-mediated sensations should not be confused with flavor sensations like coffee, chocolate, strawberry, lemon, steak sauce, barbeque sauce, etc., which are mediated via the olfactory system. During deglutition, volatiles from foodstuffs or drinks stimulate the olfactory receptors retronasally (i.e., through the nasopharynx), imparting such sensations. Additional components of flavor include texture, temperature, oral irritation, pungentness, and other somatosensory sensations. Although many of these interrelated components of flavor can be impaired or distorted following traumatic cranial nerve or brain injury, nasal or oral trauma, and surgical or medical therapies, such impairment is extremely rare. In general, most “taste” losses reflect damage to the olfactory system (see Chapters 22, 30, and 44).
