Differential effects of intra-amygdala lidocaine infusion on memory consolidation and expression of a food conditioned place preference

In the present experiments, we examined the effects of posttraining and preretention intra-amygdala infusion of the anesthetic lidocaine on memory consolidation and expression in a food conditioned place preference (CPP) task. In two separate experiments, for 4 alternating days, food deprived adult male Long-Evans rats were given access to food or no access to food during confinement for 30 min to one of two compartments in a place preference apparatus. On Day 9, the rats were given a 20-min test session and allowed access to all compartments of the apparatus. No food was present on the test day, and the amount of time spent in each compartment of the apparatus was recorded. On the test day, rats receiving saline immediately after previous training, or immediately prior to testing, spent more time in the compartment that was previously paired with food, demonstrating a food conditioned place preference (CPP). Posttraining infusion of lidocaine (2% solution, 0.5 µl/side) into the basolateral amygdala blocked acquisition, indicating that this structure is necessary for memory consolidation processes that mediate a food CPP. In contrast, immediate pretest infusion of lidocaine into the basolateral amygdala had no effect on expression of a food CPP. Taken together, the findings suggest a modulatory role for the basolateral amygdala in memory consolidation processes that underlie reward-related learning in a food CPP task.