Robust preference for a flavor paired with intragastric glucose acquired in a single trial.

Rats learn to prefer flavors followed by postingestive action of nutrients. This experiment demonstrates that such preferences can be acquired with only a single, brief pairing of a novel flavor with intragastric (IG) glucose infusion. Male rats with IG catheters consumed unflavored saccharin in daily 10-min sessions, and then received in counterbalanced order on separate days a single pairing of coffee- or vinegar-flavored saccharin with IG glucose, and of the opposite flavor with IG water. Rats subsequently preferred the glucose-paired flavor in a choice test in the absence of glucose infusion. Preference was robust, persisting through repeated non-reinforced testing.