Gustatory System

This chapter describes the human gustatory system and integrates the clinical and experimental literature. When the clinical reports contradict the experimental literature, the chapter has weighed the likelihood of a species difference versus the possibility that the disagreement reflects differences in the quality of the data. This chapter deals primarily with the central organization of the gustatory system and emphasizes its cortical organization, where most of the research over the last decade has been done. The human peripheral gustatory apparatus is described. On the anterior tongue, taste buds occur in fungiform papillae. The density of taste buds on the anterior tongues of adult cadavers varies by two orders of magnitude, and the differences are not attributable to age or race. These differences in the number of taste buds per papilla are more than an anatomical curiosity. The number of fungiform papilla correlates positively with taste intensity, the inherited ability to taste bitterness, and the intensity of the "burn" produced by capsaicin, the active ingredient in chili peppers. Furthermore, functional issues such as transduction, coding, and behavior are also covered in this chapter.