Differential involvement of the basolateral amygdala and orbitofrontal cortex in the formation of sensory-specific associations in conditioned flavor preference and magazine approach paradigms.

Abstract

Four experiments examined the roles of the basolateral amygdala and orbitofrontal cortex in the formation of sensory-specific associations in conditioned flavor preference and conditioned magazine approach paradigms using unconditioned stimulus (US) devaluation and selective Pavlovian-instrumental transfer procedures in Long Evans rats. Experiment 1 found that pre-training amygdala and orbitofrontal cortex lesions had no detectable effect on the formation or flexible use of sensory-specific flavor-nutrient associations in a US devaluation task, where flavor cues were paired either simultaneously or sequentially with nutrient rewards in water-deprived subjects. In Experiment 2, pre-training amygdala and orbitofrontal cortex lesions both attenuated outcome-specific Pavlovian-instrumental transfer. Experiment 3 indicated that amygdala lesions have no effect on the formation of sensory-specific flavor-nutrient associations in a US devaluation task in food-deprived subjects. Finally, Experiment 4 demonstrated that the outcomes used in Experiment 3 were sufficiently motivationally significant to support conditioned flavor preference. These findings suggest that, although both orbitofrontal cortex and amygdala lesions attenuate the acquisition of sensory-specific associations in magazine approach conditioning, neither lesion reduces the ability to appropriately respond to a flavor cue that was paired with a devalued outcome.