Quantifying cerebral vessel pulsatility in awake and anesthetized mice.*

Cerebrospinal fluid flows through perivascular spaces surrounding blood vessels, transporting nutrients, drugs, and metabolic waste in and out of the brain. Failure of this flow is linked to a variety of conditions, such as Alzheimer's disease. Pulsations of cerebral arteries help drive this flow, so quantifying pulsatility is crucial to understanding solute transport in the brain. Here we show how pulsatility differs for data collected from mice that are awake and anesthetized through measurement of cerebral artery diameters in microscope images. Analysis of these arterial diameter measurements and corresponding electrocardiogram data shows much higher magnitude and variance in cardiac pulsatility in awake mice over anesthetized mice. We also quantify slow vasomotion, or low frequency changes in vessel diameter.