The biological basis of food perception and acceptance

Abstract

We have discarded the old tongue map (sweet on the tip, etc.) for study of the interactions among taste nerves. Taste is mediated by the chorda tympani (anterior) and the glossopharyngeal (posterior) nerves. Unilateral anesthesia of the chorda tympani intensified some taste sensations from the area innervated by the contralateral glossopharyngeal. For some subjects, even with no stimulation, a phantom taste sensation appeared in the area innervated by the contralateral glossopharyngeal nerve. Thus when one taste nerve is damaged another compensates; however, the cost may be a taste phantom. Work on genetic variation in taste has identified supertasters of PROP (6- n-propylthiouracil) who are unusually sensitive to bitters and sweets as well as the burn from chili pepper (active ingredient capsaicin). Supertasters appear to have more tastebuds and since tastebuds have trigeminal neurons (mediating pain) associated with them, there is an association between perception of taste and irritation.