Sleep-dependent enhancement of emotional memory in early childhood

Laura B F Kurdziel,Jessica Kent,Rebecca M C Spencer

doi:10.1038/s41598-018-30980-y

Laura B F Kurdziel, Jessica Kent + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-30980-y

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Abstract

Naps in early childhood support declarative memory consolidation. However, emotional memories are unique in the neural basis of encoding as well as the sleep physiology underlying consolidation. Specifically, while consolidation of declarative memories has been associated with slow wave sleep, a prevailing theory suggests that REM sleep is necessary for consolidation of memories with emotional valence. Thus, we presented children (34–64 months) with faces paired with mean or nice descriptions. There were no significant main effects of emotional valence on recognition memory. Change in memory accuracy also did not differ when probed after a nap compared to the change in memory accuracy after an interval awake. However, when memory was probed again following overnight sleep, the change in memory accuracy was greater if the child napped the previous day. Greater nap slow wave activity was associated with greater memory decay during the nap. Yet nap slow wave activity also predicted greater overnight improvement in memory. These results suggest that sleep bouts can interact to benefit memory in early childhood.

Highlights

Childhood is a critical time for emotional development as language skills and the ability to regulate thoughts and behaviors emerge[1]
As we would not expect sleep to yield performance benefits if the nap was of insufficient length, we further excluded children (n = 8) whose nap length was less than one standard deviation (SD = 22.99 min) below the mean (M = 71.92 min)
Given that changes in memory were observed across the 24-hr period, we considered whether overnight sleep alone was sufficient for these effects

Summary

Introduction

Childhood is a critical time for emotional development as language skills and the ability to regulate thoughts and behaviors emerge[1] To capitalize on this developmental window, socio-emotional curriculum is recommended in early education settings. Emotional attention biases are reduced following a nap compared to an equal interval awake It is unknown whether emotionally valenced memories are consolidated over naps in early development. Naps may not be sufficient for emotional memory consolidation If such were the case, REM in subsequent overnight sleep may support delayed emotional memory processing. To address whether naps contribute to memory consolidation for items with emotional valence in early childhood, we examined performance on an emotional memory task following a nap and an equivalent interval spent www.nature.com/scientificreports/

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