Beyond Life: Exploring Hemodynamic Patterns in Postmortem Mice Brains

Abstract

We use Laser Speckle Contrast Imaging (LSCI) for transcranial visualization of cerebral blood flow microcirculation in mice during and after cardiac arrest. Analyzing time series of LSCI images, we observed temporal variations in blood flow distribution across the brain surface for up to several hours postmortem. Utilizing Fast Fourier Transform (FFT) analysis, we depicted the decay in blood flow oscillations and microcirculation following death. Due to the exponential drop in blood flow intensity and ensuing non-stationary conditions, Continuous Wavelet Transform (CWT) was applied to identify potential spatial or temporal synchronization patterns in cerebral hemodynamics. Additionally, we conducted Non-negative Matrix Factorization (NMF) analysis with four components to segment LSCI images, revealing temporal alterations in structural subcomponents. This integrated approach, combining LSCI, FFT, CWT and NMF, provides a comprehensive tool for understanding cerebral blood flow dynamics in mice, metaphorically capturing the ‘end of the tunnel’ experience. Results indicated a primary localization of hemodynamic activity in the olfactory bulbs postmortem, followed by minor successive relocations of blood microflows between the somatosensory and visual cortical regions via the superior sagittal sinus. The proposed approach opens avenues for further exploration into these phenomena, potentially bridging the gap between neuroscientific understanding and the longstanding mysteries surrounding consciousness and perception at the end of life.