Lidocaine infusion in a critical region of cerebellum completely prevents learning of the conditioned eyeblink response.

New Zealand white rabbits were implanted with cannulas in the dorsal or ventral aspect of the anterior interpositus nucleus. Three days (and 6 days for some dorsal-infusion animals) of standard tone-airpuff training was given with continuous infusion (constant rate of 0.2 microL/min) of lidocaine or saline. All animals were then given 3 days of training with no infusion. All lidocaine-infused animals exhibited no conditioned responses in the 3 or 6 days of infusion training. Dorsal-infusion animals learned in the subsequent 3 days of no infusion training as if naive, that is, they exhibited no savings. Animals with ventral cannula locations learned during infusion training, as shown in postinfusion training. These results strongly support the hypothesis that the essential memory trace for eyeblink conditioning is formed and stored in the cerebellum.