Chemoreceptor systems, oral

The second type of study which has contributed to our understanding of the functional properties of oral chemoreceptor systems is human psychophysics, where verbal reports are taken on the taste properties of food and beverages and their chemical constituents. It is often possible for an individual to break a flavor complex down into a variety of distinguisable sensations. These sensations are end products of neural processing that are available to consciousness. Any natural food is of complex chemical composition and thus activates a wide variety of oral and nasal chemoreceptors. These flavor sensations may arise entirely from the oral cavity or require both oral and nasal stimulation. 

Although it is common to assert that there are only four distinct taste sensations, even a casual introspection reveals that other oral sensations can be distinguished. As one may expect, flavor chemists have discovered that many separate oral sensations are required to reconstruct the flavors of foods and beverages. Some of these sensations have distinct oral loci from which they are elicited by specified types of chemical compounds, thus indicating that different neural systems are involved. Many of these sensations are difficult to typify verbally and also often have affective overtones. These sensations are the result of considerable peripheral and central neural processing and are only indirectly related to the peripheral neural pulse signals as discussed above. The type of sensation elicited and the locus of elicitation provide us with further measures of the functional properties of oral chemoreceptor systems. 

Studies on human taste sensations confirm and extend our understanding of the types of chemical signals measured by these oral chemoreceptor systems. There are, for instance, several distinct sensations elicited by chemical stimulation of fungiform papillae innervated by the geniculate ganglion, indicating that a neural functional complexity similar to that described above for... 

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