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Sleep. 2017 Mar 1;40(3). doi: 10.1093/sleep/zsx003.

Enhanced Memory Consolidation Via Automatic Sound Stimulation During Non-REM Sleep.

Author information

1
Finnish Institute of Occupational Health, Helsinki, Finland.
2
Cognitive Brain Research Unit, Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
3
Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
4
Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL.
5
Department of Physiology, University of Helsinki, Helsinki, Finland.
6
Cicero Learning Network, University of Helsinki, Helsinki, Finland.
7
Department of Psychiatry, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
8
Department of Health, National Institute for Health and Welfare, Helsinki, Finland.

Abstract

Introduction:

Slow-wave sleep (SWS) slow waves and sleep spindle activity have been shown to be crucial for memory consolidation. Recently, memory consolidation has been causally facilitated in human participants via auditory stimuli phase-locked to SWS slow waves.

Aims:

Here, we aimed to develop a new acoustic stimulus protocol to facilitate learning and to validate it using different memory tasks. Most importantly, the stimulation setup was automated to be applicable for ambulatory home use.

Methods:

Fifteen healthy participants slept 3 nights in the laboratory. Learning was tested with 4 memory tasks (word pairs, serial finger tapping, picture recognition, and face-name association). Additional questionnaires addressed subjective sleep quality and overnight changes in mood. During the stimulus night, auditory stimuli were adjusted and targeted by an unsupervised algorithm to be phase-locked to the negative peak of slow waves in SWS. During the control night no sounds were presented.

Results:

Results showed that the sound stimulation increased both slow wave (p = .002) and sleep spindle activity (p < .001). When overnight improvement of memory performance was compared between stimulus and control nights, we found a significant effect in word pair task but not in other memory tasks. The stimulation did not affect sleep structure or subjective sleep quality.

Conclusions:

We showed that the memory effect of the SWS-targeted individually triggered single-sound stimulation is specific to verbal associative memory. Moreover, the ambulatory and automated sound stimulus setup was promising and allows for a broad range of potential follow-up studies in the future.

KEYWORDS:

EEG; acoustic stimulation; auditory-evoked K-complex.; memory; slow-wave sleep

PMID:
28364428
PMCID:
PMC5806588
DOI:
10.1093/sleep/zsx003
[Indexed for MEDLINE]
Free PMC Article

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