Flavor Preference Produced by Intragastric Polycose Infusions in Rats Using a Concurrent Conditioning Procedure

Prior studies demonstrate that nondeprived rats learn to prefer a flavor (the CS+) paired with intragastric (IG) nutrient infusions over another flavor (the CS-) paired with IG water infusions when the flavors are presented on alternate days. The present experiment determined if a nutrient-based preference could be established when both flavors were concurrently available. Adult female rats were fitted with two chronic gastric catheters and were given ad lib access to chow and two flavored solutions (a bitter sucrose octaacetate solution and a sour citric acid solution). Using an automated infusion system, consumption of the CS+ flavor was paired with IG infusions of 32% Polycose, and consumption of the CS- flavor was paired with IG infusions of water. Seven of the eight rats tested developed a strong flavor preference for the CS+ over the CS-; their CS+ preference increased from 53% on day 1 to 95% on day 8. (The remaining animal eventually displayed a 97% CS+ preference after it received one-bottle training with the CS flavors.) During the first several days of training, the rats tended to drink primarily one flavor per day, and consumed primarily one flavor per drinking bout. This provided them with relatively discrete flavor-consequence experiences that presumably facilitated flavor preference conditioning.