Arterial-wall origin and transient dynamics of flow- and vaso-motion activities in the awake mouse brain revealed by laser speckle contrast imaging

SignificanceCerebral vasomotion and associated flowmotion are considered crucial for optimal brain perfusion and metabolic regulation, with reduced vasomotion being linked to cerebrovascular and neurodegenerative disorders. However, the underlying mechanisms and spatiotemporal dynamics of cerebral vasomotion are still poorly understood, underscoring the need for further research and methodological approaches for its comprehensive characterization.AimWe aimed to develop an approach for comprehensively characterizing spatiotemporal vasomotion and flowmotion dynamics and apply it to study resting-state activity at vasomotion frequencies (0.05 to 0.25 Hz) in the awake mouse brain.ApproachLaser speckle contrast imaging (LSCI) was used to image cortical blood flow in awake mice with high spatiotemporal resolution. Pixel-wise wavelet transforms and pulsatility-based segmentation enabled the identification and quantification of transient events at the vasomotion frequency range.ResultsWe identified both vasomotion and flowmotion events, which displayed intermittent periods of high and low activity lasting 83.1±82.7 and 85.5±86.2 s, respectively. Temporal correlation analysis revealed the propagation of oscillatory activity from arterial walls downstream, with a delay of ∼0.33±0.58 s from the arteries to the veins.ConclusionsOur data suggest the arterial wall origin of transient vasomotion events and their consequent propagation as flowmotion in the awake mouse brain. The combined use of pulsatility imaging, wavelet analysis, and temporal clustering in the LSCI analysis provides a framework for the comprehensive characterization of vasomotion-associated blood flow dynamics.