Psychophysical evidence supporting a physiologically derived model of salt transduction mechanisms

It is known that the perceived saltiness of sodium salts varies notably with the anion. When anions other than chloride are present, attenuation of the saltiness can occur; since these anion effects can be seen in recordings from the chorda tympani nerve of animals, their origin seems to be peripheral (Ye et al., 1991). A physiological model developed from investigations with rats has been proposed to explain this "anion effect" (Ye et al., 1993). From this model, one can predict that for a given cation, as anion size increases, both the perceptual time course and the neural response time course will be slowed. The time to maximum gustatory neural response in the chorda tympani nerve has been noted to increase with increasing anion size in rats (Ye et al., 1994). However, for a given compound, transduction mechanisms vary from species to species (Kinnamon & Cummings, 1992). Thus, before applying models derived from non-humans to humans, supporting psychophysical evidence must be gathered.;Three studies were undertaken to provide such evidence. In each, the prediction that simple manual taste reaction times (in response to stimulation with various lithium, sodium and potassium salts) would increase with increasing formula weight was statistically supported by the data. Additionally, it was shown that a simple reaction times were linearly related to the square root of anion weight in sodium salts. Furthermore, the collection of intensity ratings in the third experiment allowed for a set of analyses of covariance, as well as a set of regression analyses, which showed that when the intensity differences between sodium salts is controlled for statistically, a significant difference in reaction times for the different sodium salt types still exists.