Involvement of sleep spindles in overnight declarative memory stabilization: Effects of time of incidence and spindle type

Objective Numerous studies point to the involvement of sleep spindles and slow waves in memory processes, particularly in hippocampus-dependent declarative memory. We have shown previously that the overnight change in recall performance in a declarative word pair association task correlates signific...

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Published in:Somnologie : Schlafforschung und Schlafmedizin = Somnology : sleep research and sleep medicine 2015-03, Vol.19 (1), p.30-37
Main Authors: Gruber, G., Anderer, P., Parapatics, S., Saletu, B., Schabus, M., Klimesch, W., Klösch, G., Sauter, C., Zeitlhofer, J.
Format: Article
Language:English
Subjects:
Cardiology
Internal Medicine
Medicine
Medicine & Public Health
Neurology
Otorhinolaryngology
Pneumology/Respiratory System
Psychology
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Summary:Objective Numerous studies point to the involvement of sleep spindles and slow waves in memory processes, particularly in hippocampus-dependent declarative memory. We have shown previously that the overnight change in recall performance in a declarative word pair association task correlates significantly with increased spindle activity during the night after learning compared to a control night. The current study re-evaluates this relationship in detail and explores whether the observed positive correlation of two spindle parameters measured during stage 2 (S2) sleep with overnight stabilization depend on the time of night (early vs. late) and spindle type (fast vs. slow). Methods The study included 24 healthy volunteers aged 20–30 years. Two counterbalanced nights served as either control condition without intentional learning or as an experimental condition including a declarative memory task in the evening. Performance was tested directly after learning and in the following morning. Spindle detection was based on a validated automatic algorithm, providing density and intensity of slow (≤ 13 Hz) and fast (> 13 Hz) spindles per minute S2 sleep. To obtain spindle measures during the course of the night, the entire recording period was segmented into five 90-min parts. Results Significant correlations were observed between changes (experimental night minus control night) in spindle density (r = 0.44, p 
ISSN:1432-9123
1439-054X
DOI:10.1007/s11818-015-0699-8