The adaptation of the frog tongue to bitter solutions: The effect on gustatory neural responses to acid, sugar and bitter stimuli

Abstract

1. 1. The initial phasic component of gustatory neural responses to 1 mM acid solutions was remarkedly potentiated after the frog tongue was adapted for 10 sec to 1 mM bitter solutions of quinine hydrochloride (Q-HC1), quinine hydrosulfate (Q-H 2SO 4), brucine and nicotine and 10 mM caffeine solution, while it was suppressed after the tongue was adapted to 1 mM picric acid as a bitter solution. 2. 2. The initial phasic component of gustatory neural responses to 0.5 M sugar solutions was augmented in amplitude after 10 sec adaptation to 1 mM Q-HCl. 3. 3. After 10 sec adaptation to 1 mM Q-HCl, the gustatory neural responses to 1 mM solutions of Q-HCl, Q-H 2SO 4 and brucine and 10 mM caffeine solution were depressed to various degrees, whereas the responses to 1 mM picric acid and 10 mM nicotine were scarcely affected.