A SUBSTITUTED PYRROLIDINONE, BMY-21502, AND CLASSICAL-CONDITIONING OFTHE NICTITATING-MEMBRANE RESPONSE IN YOUNG AND OLDER RABBITS

New Zealand white rabbits (N = 76; 38 at 3 months, 38 at 21-55 months) were classically conditioned for 10 90-trial sessions in the 750-msec delay paradigm using a tone conditioned stimulus (CS) and corneal air puff unconditioned stimulus (US). Young and older rabbits were divided into groups receiving paired CS-US presentations with 0, 5, or 10 mg/ kg of BMY 21502, Unpaired tone and airpuff presentations were given to control groups administered 0 or 5 mg/kg of BMY 21502. Over training sessions, the older BMY-21502-treated rabbits produced a higher percen tage of conditioned responses (CRs) and greater CR amplitude than did the vehicle-treated older rabbits. BMY 21502 did not facilitate condit ioning in the young rabbits. There were significant age differences in acquisition between the young and older vehicle-treated animals. Alth ough the BMY-21502-treated older rabbits did not achieve the asymptoti c level of performance of the young rabbits, BMY 21502 treatment resul ted in conditioning for the older rabbits that was similar to that for the younger rabbits.