The sweet taste in the calf. II. Glossopharyngeal nerve responses to taste stimulation of the tongue

Recordings were obtained from the glossopharyngeal nerve in 1-5-week-old calves during stimulation of the circumvallate tongue area with NaCl, quinine hydrochloride, citric acid, and the sweet compounds: acesulfam-K, aspartame, fructose, galactose, glucose, glycine, lactose, maltose, monellin, Na-saccharin, sucrose, thaumatin, and xylitol. All compounds except aspartame, monellin and thaumatin gave a nerve response. Glycine, followed by Na-saccharin, elicited the largest responses. Sucrose gave the largest response among the disaccharides, while there was no significant difference between the monosaccharides. Expressed as percent of the NaCl responses, the responses to glycine, sucrose, xylitol, fructose, galactose, glucose, lactose and maltose were considerably larger in the glossopharyngeal nerve than in the chorda tympani nerve. This can be taken as an indication that the posterior region of the tongue serves as the major receptive area for sweet in cattle.