Interpositus lesion abolition of the eyeblink conditioned response is not due to effects on performance.

Classical conditioning of the rabbit eyeblink response was used to study the effects of cerebellar lesions on performance in animals trained with low-intensity unconditioned stimuli (US). Animals were trained with 1 of 2 low-intensity corneal-airpuff USs paired with a tone-conditioned stimulus. This study confirms earlier findings demonstrating the differential effects of lesions of deep cerebellar nuclei on the conditioned (CR) and unconditioned responses (UR). Lesions of the anterior interpositus nucleus of the cerebellum in animals that were successfully conditioned abolished CRs without affecting UR performance.