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Sleep spindles coupled with slow oscillations in naps are associated with suppressed declarative memory consolidation in young children
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  • Eunsol Noh,
  • Sanna Lokhandwala ,
  • Ahren Fitzroy ,
  • Rebecca Spencer
Eunsol Noh
University of Massachusetts Amherst
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Sanna Lokhandwala
University of Massachusetts Amherst
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Ahren Fitzroy
University of Massachusetts Amherst
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Rebecca Spencer
University of Massachusetts Amherst

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Abstract

Coupling between slow oscillations (SOs) and sleep spindles (SPs) during sleep is known to play a key role in declarative memory consolidation in adults. In early childhood, declarative memory consolidation during naps has been separately associated with SPs and SOs. Whether this more specifically reflects an interplay of SPs and SOs in support of memory is unknown. In the present study, SOs (0.16-1.25 Hz) and SPs (10.8-13.8 Hz) in naps of 18 preschoolers were detected (5 females, M = 51.28 months, SD= 9.20). We then calculated the SO-SP coupling by the percentage of SPs coupled to SOs (SPcSO) and the percentage of SOs coupled with SPs (SOcSP) over frontal and central-parietal sites, respectively. This was based on previous studies conducted with children, which have reported findings of coupling in the cortical sites. A peri-event time histogram showed a nonuniform distribution of centro-parietal SPcSO over centro-pareital SO duration (±1.2 sec around the SO downpeak) during slow-wave sleep (SWS). Additionally, the centro-parietal SPcSO was observed to be largely affected by SO density (r(17) = 0.79, p < 0.001), but not SP density. Surprisingly, SPcSO over centro-parietal regions during SWS was associated with worse nap-related memory consolidation (r(17) = -0.48, p = 0.041). Based on our findings, we interpret the results as indicative of the existence of active mechanisms governing the coupling between SOs and SPs in children. However, it appears that these mechanisms may not yet be fully matured to effectively support memory consolidation processes in this age range.