Exploring Hippocampal Structural Differences in Habitual vs Non-habitual Nappers During Early Childhood
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During sleep, memories become less vulnerable to interference, both during overnight sleep and naps. Previous research in adults suggests this effect is partially due to a “transfer” of memories from hippocampus to cortex, but there is little research investigating this process in children. Existing literature suggests habitually napping children need naps more than non-habitually napping children because their hippocampus is less mature. This study examines the relation between habitual versus non-habitual nappers and the hippocampus in early childhood. The participants are part of a larger ongoing study, from which we had 21 participants (Mage= 4.49 years, SD=0.51, 9 female). Of the 21 participants, 8 were nappers (napped 5+ days/week) and 13 were non-nappers (napped <5 days/week). Hippocampal volumes were extracted from T1 weighted MRI scans via FreeSurfer 6.0.0 and refined with a Segmentation Adapter Tool (Morey et al., 2009). Subregions of hippocampal head, body, and tail were identified via standard anatomical landmarks (Watson et al., 1992; Weiss et al., 2005). Preliminary analyses examined possible confounding differences between groups (age, sex, and intercranial volume). There were no differences, thus these measures were not controlled for. Results showed significant differences in hippocampal tail volumes. In the left hemisphere, nappers had larger volumes than non-nappers. Although these are preliminary results, the findings support that variation in hippocampal development may relate to nap status in developing children. Future research will focus on increased sample sizes and investigate other brain regions to determine the specificity of these effects.