Unilateral storage of monocular engram in day-old chick.

Efficient interocular transfer of a one-trial passive avoidance task by the day-old domestic chicken, for whom the optic nerves decussate completely, raised the question of whether memory for the task was held in one or both sides of the forebrain. Intracranial injection of ouabain or cycloheximide to the trained hemisphere immediately after learning suppressed avoidance behaviour learned monocularly, while injection to the untrained side did not. Memory for the task was established in the side of the brain served by the eye used in learning. Interocular transfer was therefore achieved by the untrained hemisphere borrowing information from the other side's store. The presence of memories in the trained side was not sufficient to establish memory in the naive side.