Coupled electrophysiological, hemodynamic, and cerebrospinal fluid oscillations in human sleep

TLDR

Sleep is essential for cognition and brain health, with slow neural waves aiding memory consolidation and cerebrospinal fluid clearing metabolic waste, yet the connection between these processes remains unknown. Accelerated neuroimaging was used to simultaneously record electrophysiological, hemodynamic, and CSF dynamics in the human brain. During non‑rapid eye movement sleep, a coherent sequence of neural slow waves, hemodynamic oscillations, and cerebrospinal fluid flow was observed, revealing macroscopic CSF waves tightly coupled to brain activity.

Abstract

Sleep is essential for both cognition and maintenance of healthy brain function. Slow waves in neural activity contribute to memory consolidation, whereas cerebrospinal fluid (CSF) clears metabolic waste products from the brain. Whether these two processes are related is not known. We used accelerated neuroimaging to measure physiological and neural dynamics in the human brain. We discovered a coherent pattern of oscillating electrophysiological, hemodynamic, and CSF dynamics that appears during non-rapid eye movement sleep. Neural slow waves are followed by hemodynamic oscillations, which in turn are coupled to CSF flow. These results demonstrate that the sleeping brain exhibits waves of CSF flow on a macroscopic scale, and these CSF dynamics are interlinked with neural and hemodynamic rhythms.