SLEEP, Volume 41, Issue 12, 1 December 2018, zsy176
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DOI: 10.1093/sleep/zsy176

Péter Simor1, Emilie Steinbach2, Tamás Nagy1, Médhi Gilson2, Juliane Farthouat2, Rémy Schmitz2, Ferenc Gombos3, Péter Ujma4,5, Miklós Pamula4, Róbert Bódizs4,5,

Philippe Peigneux2

 

1 Institute of Psychology, Eötvös Loránd University, Budapest, Hungary
2 UR2NF – Neuropsychology and Functional Neuroimaging Research Group at CRCN – Center for Research in Cognition and Neurosciences and UNI – ULB Neurosciences Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium
3 Department of General Psychology, Pázmány Péter Catholic University, Budapest, Hungary
4 Semmelweis University, Institute of Behavioural Sciences, Budapest, Hungary
5 National Institute of Clinical Neurosciences, Budapest, Hungary
 
 

Abstract

Slow wave sleep (SWS) is characterized by the predominance of delta waves and slow oscillations, reflecting the synchronized activity of large cortical neuronal populations. Amongst other functions, SWS plays a crucial role in the restorative capacity of sleep. Rhythmic Acoustic Stimulation (RAS) during SWS has been shown a cost-effective method to enhance slow wave activity. Slow wave activity can be expressed in a region-specific manner as a function of previous waking activity. However, it is unclear whether slow waves can be enhanced in a region-specific manner using RAS. We investigated the effects of unilaterally presented rhythmic acoustic sound patterns on sleep EEG oscillations. Thirty-five participants received during SWS 12-seconds long rhythmic bursts of pink noise (at a rate of 1 Hz) that alternated with non-stimulated, silent periods, unilaterally delivered into one of the ears of the participants. As expected, RAS enhanced delta power, especially in its low frequency components between 0.75 and 2.25 Hz. However, increased slow oscillatory activity was apparent in both hemispheres regardless of the side of the stimulation. The most robust increases in slow oscillatory activity appeared during the first 3–4 seconds of the stimulation period. Furthermore, a short-lasting increase in theta and sigma power was evidenced immediately after the first pulse of the stimulation sequences. Our findings indicate that lateralized RAS has a strong potential to globally enhance slow waves during daytime naps. The lack of localized effects suggests that slow waves are triggered by the ascending reticular system and not directly by specific auditory pathways.

Keywords: Neural entrainment, delta power, slow oscillations, slow wave sleep, auditory stimulation, laterality