Human NREM Sleep Promotes Brain-Wide Vasomotor and Respiratory Pulsations

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  • Heta Helakari
  • Vesa Korhonen
  • Sebastian C. Holst
  • Johanna Piispala
  • Mika Kallio
  • Tommi Väyrynen
  • Niko Huotari
  • Lauri Raitamaa
  • Johanna Tuunanen
  • Janne Kananen
  • Matti Järvelä
  • Timo Tuovinen
  • Ville Raatikainen
  • Viola Borchardt
  • Hannu Kinnunen
  • Nedergaard, Maiken
  • Vesa Kiviniemi

The physiological underpinnings of the necessity of sleep remain uncertain. Recent evidence suggests that sleep increases the convection of cerebrospinal fluid (CSF) and promotes the export of interstitial solutes, thus providing a framework to explain why all vertebrate species require sleep. Cardiovascular, respiratory and vasomotor brain pulsations have each been shown to drive CSF flow along perivascular spaces, yet it is unknown how such pulsations may change during sleep in humans. To investigate these pulsation phenomena in relation to sleep, we simultaneously recorded fast fMRI, magnetic resonance encephalography (MREG), and electroencephalography (EEG) signals in a group of healthy volunteers. We quantified sleep-related changes in the signal frequency distributions by spectral entropy analysis and calculated the strength of the physiological (vasomotor, respiratory, and cardiac) brain pulsations by power sum analysis in 15 subjects (age 26.5 ± 4.2 years, 6 females). Finally, we identified spatial similarities between EEG slow oscillation (0.2–2 Hz) power and MREG pulsations. Compared with wakefulness, nonrapid eye movement (NREM) sleep was characterized by reduced spectral entropy and increased brain pulsation intensity. These effects were most pronounced in posterior brain areas for very low-frequency (≤ 0.1 Hz) vasomotor pulsations but were also evident brain-wide for respiratory pulsations, and to a lesser extent for cardiac brain pulsations. There was increased EEG slow oscillation power in brain regions spatially overlapping with those showing sleep-related MREG pulsation changes. We suggest that reduced spectral entropy and enhanced pulsation intensity are characteristic of NREM sleep. With our findings of increased power of slow oscillation, the present results support the proposition that sleep promotes fluid transport in human brain.

Original languageEnglish
JournalJournal of Neuroscience
Volume42
Issue number12
Pages (from-to)2503-2515
Number of pages13
ISSN0270-6474
DOIs
Publication statusPublished - 2022

Bibliographical note

Publisher Copyright:
Copyright © 2022 Helakari et al.

    Research areas

  • brain pulsations, fast fMRI, glymphatic clearance, sleep, slow-wave EEG, spectral power

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