Amnesia of a passive avoidance task due to the beta 2-adrenoceptor antagonist ICI 118,551.

The selective beta 2-adrenoceptor antagonist ICI 118,551 induces amnesia in the domestic chick when given systemically, 10 min after a one-trial PAL task. Young chicks will spontaneously peck at a small bright bead. If the bead has been coated with a distasteful substance, the chicks will learn in a single trial not to peck at a similar bead on subsequent presentation. Administration of ICI 118,551 prevented retention of this task. Vehicle-injected chicks which learnt the task, avoided a similar bead to the training bead in the retention test, but did not avoid a bead of a different colour. The effect of ICI 118,551 is unlikely to be a direct effect on performance since amnesic chicks pecked both beads freely and equally in the test.