Memory-related hippocampal activation during sleep and temporal memory in toddlers. (February 2021)

• Record Type: Journal Article
• Authors: Mooney, Lindsey N.; Johnson, Elliott G.; Prabhakar, Janani; Ghetti, Simona
• Is Part Of: Developmental cognitive neuroscience. Volume 47(2021)
• Publication Date: 2021-02
• Subjects: Hippocampal development -- Songs -- Episodic memory -- fMRI -- Spatial -- Temporal; Cognitive neuroscience -- Periodicals; Developmental neurobiology -- Periodicals; Neuropsychology -- Periodicals; Neuropsychiatry -- Periodicals; 612.8233
• DOI: 10.1016/j.dcn.2020.100908
• Languages: English
• ISSNs: 1878-9293

Abstract

Highlights: Two-year-olds played tablet games requiring them to remember locations visited by characters and the temporal order with which they visited them. Two-year-olds remembered spatial locations better than temporal order immediately after learning, and after a 20-minute and one-week delay. Song-related hippocampal activation during sleep is associated with memory for temporal order. Abstract: Nonhuman research has implicated developmental processes within the hippocampus in the emergence and early development of episodic memory, but research in humans has been constrained by the difficulty of examining hippocampal function during early development. In the present study, we assessed 48 2-year-olds with a novel paradigm in which participants completed two games on a tablet that required remembering associations between unique characters, the places they visited, and the temporal order with which they did so. At the completion of each game, a unique, novel song played. Toddlers remembered spatial locations better than temporal order during an immediate test, after a 20-minute delay, and after a week delay. After the last behavioral session, toddlers underwent an fMRI task during natural nocturnal sleep evaluating hippocampal activation in response to learned and novel songs. We found that the extent of hippocampal activation for learned songs compared to novel songs during sleep was correlated with memory for temproal order across all time delays, but not with memory for spatial locations. The results confirm that that the functional contribution of the hippocampus to early memory can be assessed during sleep and suggest that assessment of temporal aspects of memory in the current task best capture this contribution.