Infant learning forms lasting memory schemas that influence adult behavior

Early-life episodic experiences, despite seeming rapidly forgotten, are stored long-term in a latent form. The contribution of this unique hidden memory storage is not understood. Here, we show that contextual memories formed in infant mice are recovered in adulthood following weak behavioral reminders (savings) of the infantile experience. Savings in adults also facilitates new congruent learning but fails to influence other types of hippocampus-dependent learning, and this facilitation is a developmental prerogative. Both infant memory reinstatement and facilitation of new learning in adults are context-specific and functionally re-engage subsets of the prelimbic/infralimbic (PL/IL) and anterior cingulate cortex (ACC) neural networks activated in infancy. New adult learning also re-engages the dorsal hippocampus (dHC) along with PL/IL-dHC and ACC-dHC neuronal projections that were activated during infant learning. Thus, infant memories store information for a long time as memory schemas that support relearning and the formation of new congruent memories in adulthood.