Episodic memory, that is, memories of specific events with their details, forms the basis of personal experience and identity. It is already known that it works in children, but the mechanisms of its development have been studied mainly at the stages of encoding and retrieval. The intermediate stage of consolidation, when the brain stabilizes fresh memories, has hardly been studied in children. Adult studies show that immediately after learning, the brain spontaneously "replays" what it has learned, but whether this happens in children and how it relates to memory quality remained unknown. The work sits at the intersection of memory neuroscience and developmental psychology, complementing research on the role of the hippocampus in childhood.
Children aged 6 to 17 performed a memory task in the scanner: they were shown a scene, then an object or face in a specific location within that scene. Before and after learning, five-minute resting-state scans were conducted, during which participants simply looked at a cross. After the scanner, memory was tested: they had to choose which object was in which scene and where exactly it was located. Brain activity during encoding was compared for events that were later remembered or forgotten. Then they looked for whether the activity patterns of remembered events were replayed during rest, comparing them with patterns during encoding.
Children remembered events as a whole, that is, they linked the object, scene, and location, at a level above chance (on average 40.61% with a chance level of 12.5%). During encoding of remembered events, the right anterior hippocampus was more strongly activated, as well as the occipital and parietal cortex. During rest after learning, the activity patterns of remembered events were replayed in the medial prefrontal cortex, the angular gyrus, and the left precentral gyrus. The age effect was not in encoding but in replay: in younger children, the replay area in the prefrontal cortex was larger than in older ones. At the same time, memory quality did not change with age.
The work shows for the first time that spontaneous replay of memories during wakefulness occurs already in childhood and predicts future recall. This distinguishes it from neighboring studies that focused on encoding or retrieval rather than consolidation. The age-related decrease in the replay area in the prefrontal cortex is consistent with the general principle of "from diffuse to local" in brain development. It turns out that consolidation mechanisms continue to mature during adolescence, even when behavioral memory measures are already stable.
Further research can clarify the exact role of replay in different areas: whether it strengthens specific details or builds generalized schemas. It will be important to separate conscious reflection on memories from unconscious replay, since in adults they affect memory differently. It is also worth checking how replay relates to the vividness of memories and to the formation of generalized knowledge.
The results may be useful in pedagogy and child psychology, helping to understand how to organize breaks after learning for better memorization. They are also important for studying memory disorders in children.
Repeat the study on a larger sample to confirm the age effects. Add a survey of children about their thoughts during rest and check how replay relates to generalization of experience.
The work addresses the unresolved question of which stages of memory continue to develop in childhood and adolescence. It shows that consolidation, not just encoding, may be a source of age-related changes. The question of the balance between preserving specific details and forming generalized schemas in the developing brain remains open.
Children who thought about the task during rest remembered better, but their neural replay did not differ from those who did not think about it. This means that the brain consolidates memories even without conscious effort.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.