Operant licking in rabbits for intraoral injection of basic types of tastants

In order to compare and contrast hedonic properties of 0.75 M NaCl and 0.5 M sucrose used in behavioral electrophysiology of taste, tests were carried out of evoked patterns of orolingual response and operant licking on a FR-32 schedule to discrete intraoral injections of these stimuli and other basic types of tastants. In tests of taste reactivity, NaCl and sucrose evoked quantitatively similar numbers of orolingual response in excess of those evoked by water. NaCl was also similar to sucrose in amount of operant licking generated at the outset of the test session. Both of these stimuli were more effective than either 0.02 M HCl, 0.01 M QHCl, or water. The NaCl also did not have the suppressant effect of HCl when alternated with sucrose as the reinforcement for licking. NaCl differed from sucrose in sustaining operant licking. While NaCl would appear to share the same basic hedonic value of sucrose, long-term associative processes pertaining to postingestional consequences of fluid input and short-term sensory processes may act to limit behavioral responsivity for concentrated NaCl. Additional information was obtained on operant licking for sodium saccharin.