beta-Adrenergic involvement in acquisition vs. extinction of a classically conditioned eye blink response in rabbits.

beta-adrenergic involvement in classical conditioning and extinction was investigated. Five groups of rabbits (saline, 1, 3, 5 or 10 mg kg-1 of the beta-adrenergic antagonist propranolol) were trained with a tone conditioned stimulus (CS) paired with a corneal air puff unconditioned stimulus (US). Both 5 mg kg-1 and 10 mg kg-1 propranolol delayed acquisition of conditioned responses but all groups were able to learn the task to criterion. Consistent changes were not seen during extinction.