title: Enhanced Memory Consolidation Via Automatic Sound Stimulation During Non-REM Sleep.
abstract: 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.
  
  
  
  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.
  
  
  
  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 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.
  
  
  
  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.
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland.|Cognitive Brain Research Unit, Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland.|Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
authors.forename: Miika M
authors.initials: MM
authors.lastname: Leminen
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Virkkala
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland.
authors.forename: Emma
authors.initials: E
authors.lastname: Saure
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland.
authors.forename: Teemu
authors.initials: T
authors.lastname: Paajanen
authors.affiliation: Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL.
authors.forename: Phyllis C
authors.initials: PC
authors.lastname: Zee
authors.affiliation: Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Santostasi
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland.
authors.forename: Christer
authors.initials: C
authors.lastname: Hublin
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland.
authors.forename: Kiti
authors.initials: K
authors.lastname: Müller
authors.affiliation: Department of Physiology, University of Helsinki, Helsinki, Finland.
authors.forename: Tarja
authors.initials: T
authors.lastname: Porkka-Heiskanen
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland.|Cognitive Brain Research Unit, Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland.|Cicero Learning Network, University of Helsinki, Helsinki, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Huotilainen
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland.|Department of Psychiatry, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland.|Department of Health, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Tiina
authors.initials: T
authors.lastname: Paunio
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D000069077:Memory Consolidation / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D013016:Sound; D011795:Surveys and Questionnaires
keywords: EEG; acoustic stimulation; auditory-evoked K-complex.; memory; slow-wave sleep