Limbic-dependent recognition memory in monkeys develops early in infancy.

Infantile amnesia, the absence of memories from infancy and early childhood, has been attributed to an immaturity of the limbic system in infancy. Contrary to this view, we now report that limbic-dependent recognition memory is present as early as one month of age in monkeys. Memory measured by the paired-comparison preferential looking task, normally present in infant monkeys within the first month of life, is absent after damage to the amygdaloid complex and hippocampal formation, suggesting that limbic structures make a critical contribution to visual recognition memory even at this early age. The findings reopen the question of the locus of the neural immaturity that underlies infantile amnesia.