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Updated: Jun 7, 2026
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Quantifying Infra-slow Dynamics of Spectral Power and Heart Rate in Sleeping Mice
Published on: August 2, 2017
Infra-slow (<0.1 Hz) Modulation of Human Brain Pulsations in Awake and Sleep States.
Tommi Väyrynen1,2,3, Heta Helakari4,2,3, Vesa Korhonen4,2,3,5
1Oulu Functional Neuroimaging, Faculty of Medicine, University of Oulu, Oulu 90014, Finland tommi.vayrynen@oulu.fi.
Summary
Brain pulsations, including infra-slow fluctuations (ISF), interact to drive cerebrospinal fluid flow. ISF dynamics predict faster pulsations, especially during sleep, enhancing brain fluid clearance.
Area of Science:
- Neuroscience
- Physiology
- Medical Imaging
Background:
- The human brain has three main pulsations: cardiovascular, respiratory, and infra-slow fluctuations (ISF <0.1 Hz).
- These pulsations are crucial for intracranial fluid flow and waste clearance, particularly during sleep.
- Interactions between these pulsations have not been thoroughly investigated.
Purpose of the Study:
- To investigate the mutual dependencies and cross-frequency coupling of brain pulsations.
- To explore how these interactions differ between awake and NREM sleep states.
- To understand the role of pulsations in driving intracranial fluid transfer.
Main Methods:
- Utilized ultrafast whole-brain MREG fMRI in 23 healthy volunteers (awake and NREM sleep).
- Analyzed frequency domain up to 5 Hz for cross-frequency oscillatory interactions.
- Employed phase transfer entropy (TE) analysis to assess directed coupling.
Main Results:
- Awake state: Resting state network (RSN) activity predicted neurofluid (NF) signal changes.
- NREM sleep: Increased ISF power and altered directed coupling between RSN and NF.
- Identified three cross-frequency coupling bands (ISF, respiratory, cardiovascular); slower pulsations predicted faster ones, with an inverted cardiorespiratory coupling in NREM-2 sleep.
Conclusions:
- Directional, ISF-mediated mechanisms underlie brain pulsations driving intracranial fluid transfer.
- Novel cross-frequency coupling bands were discovered, linking ISF dynamics to faster pulsations.
- These findings suggest enhanced perivascular clearance during sleep via pulsation interactions.
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