Brain electro/hydrodynamic drive of vasomotor waves inverts locally in NREM sleep.

Motivation: Vasomotor waves increase in sleep but their causal impact on brain electrical activity and hydrodynamics is not understood. Goal(s): We wanted to find out what is driving sleep related glymphatic solute transport. Approach: We used multimodal 3D whole brain MREG, dcEEG and waterNIRS simultaneously to find out what VLF < 0.1 Hz pulsation is driving the other(s). Results: In sleep the normal causal electro/hydrodynamic drive of the vasomotor BOLD waves reverses locally near upper parasagital and deeper structures. Impact: The driver of the increase brain solute transport in human sleep has been unknown. In out ultrafast multimodal MREG study, we show significant reversals in the causal drive of vasomotor waves locally.