Insular cortex lesions fail to block flavor and taste preference learning in rats.

The role of the insular cortex (IC) in learning to associate orosensory cues with the oral and post-oral properties of carbohydrate was examined. Rats with either small (gustatory region) or large (gustatory and visceral regions) ibotenic acid lesions of the IC learned to prefer flavors (Experiments 1 and 3) and taste mixtures (Experiments 2 and 4) paired with intragastric infusions of maltodextrin. The rats with large IC lesions also learned a preference for a flavor cue paired with the sweet taste of fructose (Experiment 5). In fact, they showed enhanced conditioning and retarded extinction compared with controls. Collectively, these data provided no evidence that IC is essential for flavor preference learning based on associations between the orosensory cues and the oral and post-oral reinforcing properties of nutrients.