GUSTATORY AND THERMAL RESPONSES IN THE GLOSSOPHARYNGEAL NERVE OF THE RABBIT AND CAT

Abstract

1. The glossopharyngeal nerve responses in rabbits and cats to taste and thermal stimulation of the posterior third of the tongue were recorded.
2. The nerve shows responses to water, 0.5 M NaCl, 0.5 M KCl, 0.02 M quinine hydrochloride, 0.005 N HCl and 0.5 M sucrose in rabbits, and in cats to 1 M NaCl, 1 M KCl, 0.02 M quinine and 0.01 N HCl but not to water and 0.5 M sucrose.
3. The response to taste stimulation of the circumvallate papilla in rabbits has a latency of several sec and shows a characteristic gradual time-course, but the response to taste stimulation of the foliate papillae in rabbits and that of the circumvallate papillae in cats attain a maximum rapidly.
4. In rabbits relative magnitudes of response to 0.02 M quinine, 0.005 N HCl, 0.5 M sucrose and 0.5 M KCl are greater than those in the chorda tympani, and in cats those for 0.02 M quinine and 0.01 N HCl are also greater than those in the chorda tympani.
5. The response to NaCl increases with an increase in NaCl concentration up to 4 M in both rabbits and cats.
6. The response in rabbits is mainly originated from the foliate papillae, and threshold for stimulation of the circumvallate papilla in this species is very high. The response in cats is mainly attributed to the circumvallate papillae because the foliate papillae in cats show little response.
7. The nerve responds well to both cooling and warming of the tongue in both animal species.