Classical eyeblink conditioning in decerebrate guinea pigs

A decerebrate guinea pig preparation was used to test the hypothesis that brainstem-cerebellar circuitry is sufficient for classical delay eyeblink conditioning. Delay conditioning was carried out using a tone conditioned stimulus (CS) paired with a co-terminating, periorbital shock unconditioned stimulus (US). Decerebrate animals readily acquired the conditioned response (CR), while pseudoconditioning yielded no signs of learning. When a longer tone CS was used, the learning became slower. These CRs were adaptive and appropriately timed relative to the US. Subsequent CS-alone trials caused extinction of the CR. These characteristics of the eyeblink conditioning were similar to those reported previously in various species, suggesting that the cerebellum and brainstem are sufficient for this type of learning.