Arginine vasotocin delays extinction of a conditioned avoidance behavior in neonatal chicks

One minute after single-trial avoidance conditioning, young cockerels received intracerebroventricular or intraperitoneal injections of saline or arginine vasotocin (dose range: 0.004 to 16 micrograms/chick). Retroactive enhancement of the learned response was observed 24 hours post-training for some dose levels, but not for others. A 0.4 micrograms vasotocin dose also delayed extinction when injected 9 minutes after training. Behavioral similarities between avian and mammalian responses to vasotocin and other neuroactive peptides are discussed.