Single sweetness signal

• Published in: Nature (London) 1994-06, Vol.369 (6480), p.447-448
• Main Authors: Breslin, P. A. S., Kemp, S., Beauchamp, G. K.
• Format: Article
• Language: English
• Subjects: Fructose; Glucose; Humanities and Social Sciences; Humans; multidisciplinary; Science; Science (multidisciplinary); scientific-correspondence; Sensory Thresholds; Sucrose; Taste - physiology
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/369447a0

The number of neural signals encoding information (coding dimensionality) about sweet-tasting compounds is vigorously debated. One hypothesis is that many signals are involved at every level of coding: accordingly, each physically distinct, sweet-tasting compound binds to a distinct population of receptors, producing a unique pattern of activity at the receptor level and all subsequent levels of coding. An alternative hypothesis is that only one or a few signals encode information about sweet-tasting compounds. To investigate the coding dimensionality of three simple saccharides, alpha -D-glucose, alpha -D-fructose and sucrose ( alpha -D-glucopyranosyl- beta -D-fructofuranoside), we used a two-alternative, forced-choice taste discrimination protocol. In each session a subject was required to discriminate a standard stimulus, S, from a test stimulus, T, that varied in concentration (all solutions were allowed to muto-rotate for 24 hours). We conclude that, within the concentration ranges tested, glucose, fructose and sucrose are indeed indiscriminable when their relative concentrations are suitably adjusted, and therefore that normal subjects are monogeusic for these saccharides. The finding of monogeusia implies that under the present experimental conditions the three sugars investigated act identically somewhere along a common sensory pathway. Similar arguments have emerged from the study of photopic (day vision) and scotopic (night vision) light matching.