A Comparison of Neural and Psychophysical Responses to Taste Stimuli in Man

Abstract

Diamant, H. B. Oakley, L. Ström, C. Wells and Y. Zotterman. A comparison of neural and psychophysical responses to taste stimuli in man. Acta physiol. scand. 1965 64. 67–74. – Electrophysiological records of taste activity have been obtained from the chorda tympani nerve of otosclerotic patients. When possible, preoperative psychophysical responses to taste stimuli were also obtained. The summated chorda tympani discharge to 0.2 M NaCl adapts completely and the time required agrees with psychophysical reports. Psychophysical estimates of the sweetness of different sugars correspond closely with nerve response magnitudes. Gymnema extract abolishes both the sweet sensation and the nerve response to sweet tasting chemicals. The total sum of taste activity in the entire chorda tympani nerve appears to be an important determinant of the psychophysical responses. There are large individual differences in the relative size of the neural response to different taste stimuli. Responses to ethyl alcohol are described.

Masking and adaptation of sugar sweetness intensity

“…The exact nature of this mechanism is unknown, but there is evidence that adaptation is peripheral in nature [4,39].…”

Molecular Mechanisms for Sweet-suppressing Effect of Gymnemic Acids

“…It is known that GAs selectively suppress taste responses to various sweet compounds without affecting responses to salty, sour, and bitter substances for 30 -60 min after application of GAs in * This work was supported in whole or part by KAKENHI Grants 18109013, humans (21,22). The sweet-suppressing effect of GAs is specific to humans and chimpanzees; it has no effect on sweeteners for rodents (23)(24)(25)(26)(27). This effect is diminished by rinsing the tongue with ␥-cyclodextrin (CD) (28 -30).…”

Theory for the mechanism of action of “miracle fruit”

“…It has already been concluded by Diamant, Oakley, Strom, Wells, and Zotterman (1965), on the basis of electrophysiological recordings from human subjects, that the active substance works peripherally. From the point of view of the new theory of sweet, and of the data discussed above, it seems likely that the active principle of Gymnema sylvestre straddles the sweet sites, and prevents the protons from being removed.…”