Gustatory modality

The next point for consideration is whether pungency is a purely gustatory modality, or whether it is also an olfactory modality. There is a vast and growing literature on the interrelation of the senses, though the extent of their mutual influences are... 

That the sweet and bitter responses are intimately associated is clear from the results of gustatory studies of all of the conformationally defined sugars and of other organic compounds. If a carbohydrate has any taste at all, this is invariably sweet, bitter-sweet, or bitter. Chemical modification may alter the taste of a sweet compound so that the product is bitter-sweet or bitter, and it is now generally agreed that the two basic tastes may each be a feature of a single compound. It appears, therefore, that the interactions of these polyfunctional stimulants involve two different sets of receptor sites, representing sweet and bitter modalities. ... 

A century ago, Fick proposed the concept of four primary tastes, namely, sweet, salty, sour, and bitter. It has since been found that taste sensations are not describable by a single collection of discrete primaries. Electrophysiological studies of afierent taste-units in the chorda tympani and glossophyrangeal nerves have revealed that a continuous spectrum of gustation may be based on these four taste elements. Furthermore, the intensities of the tastes that we commonly experience are due not only to gustatory sensations but also to tactile, hot and cold, and, above all, olfactory sensations. The complexities of taste studies are such that, unless one of the taste modalities is singled out for study, there is very little hope of success. 

Drosophila gustatory receptor (GR) genes a gene family that subserves both gustatory and olfactory modalities... 

Figure 15.1 The sequence of behaviors in heterosexual courtship of Drosophila melanogaster. The arrows represent the known sensory modalities by which flies communicate (+) for stimulatory and (-) for inhibitory signals. Olfactory and gustatory cues are represented respectively by white and black arrows auditory and visual cues by light and dark gray arrows. Several cuticular hydrocarbons exchanged during each sequence can affect precise behaviors 5-and 7-tricosene (respectively 5-T and 7-T), 7,11-hepta- and nonacosadiene (7,11-HD 7,11-ND) and 7- and 9-pentacosene (7-P 9-P see text). (Adapted from Ferveur and Sureau, 1996 Greenspan and Ferveur, 2000.)...

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