Ingestion affected by the oral environment: The role of gustatory adaptation on taste reactivity in the rat

Three experiments were performed to determine (1) the time course of changes in ingestive behavior associated with oral infusion of taste substances, and (2) the possible role of changes in the tonic chorda tympani response in the behavioral effect of oral infusion. Experiments 1 and 2 examined 2 different procedures with a variety of sapid solutions to detect alterations in ingestion following oral adaptation. Decrements in Na-saccharin licking were found over a 2-hr period of continuous Na-saccharin stimulation suggesting that gustatory adaptation in the rat extends over a considerable time period and that the effect of the infusion was to alter the incentive motivation properties of the sapid substance. Experiment 3 sought an altered tonic responsivity of the chorda tympani nerve which might correlate with the decrement in ingestion seen in Experiment 2. No evidence of a neural decrement over a 2-hr time was found and it was concluded that central processes were probably involved in the behavioral adaptation found in the second experiment.