Electrophysiological indicators of sleep‐associated memory consolidation in 5‐ to 6‐year‐old children

• Published in: Psychophysiology Vol. 58; no. 8; pp. e13829 - n/a
• Main Authors: Joechner, Ann‐Kathrin, Wehmeier, Sarah, Werkle‐Bergner, Markus
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.08.2021
• Subjects: Activity patterns; Animal memory; Association Learning; Brain Waves - physiology; Cerebral Cortex - physiology; Child; Child Development - physiology; Child, Preschool; Children; EEG; Female; Humans; individualized rhythm detection; Male; Memory Consolidation - physiology; Oscillations; Polysomnography; Sleep; sleep spindles; individualized rhythm detection; sleep; sleep spindles; children; EEG
• ISSN: 0048-5772; 1469-8986; 1540-5958
• DOI: 10.1111/psyp.13829

In adults, the synchronized interplay of sleep spindles (SP) and slow oscillations (SO) supports memory consolidation. Given tremendous developmental changes in SP and SO morphology, it remains elusive whether across childhood the same mechanisms as identified in adults are functional. Based on topography and frequency, we characterize slow and fast SPs and their temporal coupling to SOs in 24 pre‐school children. Further, we ask whether slow and fast SPs and their modulation during SOs are associated with behavioral indicators of declarative memory consolidation as suggested by the literature on adults. Employing an individually tailored approach, we reliably identify an inherent, development‐specific fast centro‐parietal SP type, nested in the adult‐like slow SP frequency range, along with a dominant slow frontal SP type. Further, we provide evidence that the modulation of fast centro‐parietal SPs during SOs is already present in pre‐school children. However, the temporal coordination between fast centro‐parietal SPs and SOs is weaker and less precise than expected from research on adults. While we do not find evidence for a critical contribution of SP–SO coupling for memory consolidation, crucially, slow frontal and fast centro‐parietal SPs are each differentially related to sleep‐associated consolidation of items of varying quality. Whereas a higher number of slow frontal SPs is associated with stronger maintenance of medium‐quality memories, a higher number of fast centro‐parietal SPs is linked to a greater gain of low‐quality items. Our results demonstrate two functionally relevant inherent SP types in pre‐school children although SP–SO coupling is not yet fully mature. In adults, sleep supports the long‐term stabilisation of memories. System consolidation theories propose the coupling of sleep slow oscillations and spindles during non‐rapid eye movement sleep as a key mechanism. Does the same hold true in young children? Our results provide evidence for two functionally relevant sleep spindle types in pre‐school children despite immature sleep spindle – slow oscillation coupling.