Juvenile rat’s sleep enables schema memory across episodes before expression of memory for individual episodes
Year: 2026
Type: preprint
Abstract: Schema memory refers to generalized knowledge extracted from multiple related episodes. According to systems consolidation theory, such representations emerge during sleep through the transformation of hippocampus-dependent episodic memories into neocortical schema representations. Whether this process requires mature episodic memory expression during early development remains unclear. Here, we examined schema formation in infant rats with an immature hippocampus. At postnatal day (PD) 25, pups (n=24) were tested in an adapted object–place paradigm enabling abstraction of a spatial regularity across eight consecutive episodes. Following encoding, pups either slept or remained awake for two hours, and schema memory was tested 22 hours later. Control groups were exposed to pseudorandomized object configurations. Schema memory was expressed only after exposure to spatial regularities and only when sleep followed encoding. To directly assess episodic memory under comparable conditions, an additional group of pups (n=12) was tested in a standard single-episode object–place recognition (OPR) task with post-encoding sleep. At a 4-hours test, these pups did not show episodic object–place memory. These findings indicate that sleep supports schema memory formation during early life under conditions in which the expression of robust single-episode memory is not yet evident, suggesting that schema abstraction in infancy does not depend on fully developed hippocampal episodic representations. Statement of significance How the brain extracts generalized knowledge across multiple experiences during early life remains poorly understood. Prevailing theories propose that schema representations originate during sleep from hippocampal representations of individual episodes. Yet the hippocampus is functionally immature in juveniles, raising the question whether schema abstraction occurs before the episodic memory system is fully developed. We provide evidence in rats that juveniles can form spatial schemas across episodes, even though they do not yet show mature expression of memory for a single episode. The pups formed schema memory only when they slept after the experiences. These findings suggest that during infancy sleep supports the emergence of generalized knowledge through mechanisms that differ from those described in adults, pointing to a developmentally distinct organization of memory systems.
Authors: Julia Fechner, Jan Born, Marion Inostroza
Language: English
Topic: Memory and Neural Mechanisms
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Funder: Deutsche Forschungsgemeinschaft
Awards: G5867724527, G8711290490
OpenAlex ID: W7213459632