Hippocampal ripples linked to recognition memory judgments in children

Abstract

Intracranial studies have demonstrated significant roles for hippocampal ripples in human declarative memory. Yet, the developmental trajectory and contribution of ripples to memory processes in children remain unknown. We studied hippocampal ripple activity using intracranial recordings in 14 children (age: 6-14) undergoing epilepsy monitoring. After watching a pink panther cartoon twice, participants engaged in an old/new recognition test, determining whether events portrayed in short (4s) videoclips stemmed from the cartoon they had just viewed. Our results reveal a significant rise in ripple rate during successful recognition of familiar events. An anticipatory decline in ripple rate preceded recognition errors. Interestingly, when participants viewed the cartoon passively during the initial full-length screenings, the overall temporal pattern of ripple activation remained consistent across repetitions, and significantly distinct from explicit recognition. We conclude that hippocampal ripples in children play a key role in declarative memory, supporting the explicit identification of previously encountered events.