Temporal Variability Analysis of Cortical Blood Flow in Rats with Hyperacute Cerebral Ischemia

Cerebral ischemia restricts cerebral blood flow (CBF), leading to unstable hemodynamics. Past studies of ischemia mainly focused on cortical CBF reduction. However, its impact on hemodynamic changes, especially temporal varying characteristics, remains poorly understood. Here, we collected cortical resting-state CBF in rats with left carotid artery blockage during occlusion-reperfusion, and measured the temporal variability and changes in laterality using a novel state-space method. This method was also applied to stroke EEG datasets to validate its effectiveness. After arterial occlusion, the left marginal motor, sensory, auditory, and visual cortices exhibited severe temporal variability impairments. The laterality analysis indicated that affected left regions showed inferior unilateral mean, inter-hemispheric transition probability, time fraction, and laterality duration, while the right side had a higher laterality time fraction and duration. These impairments recovered partially following blood flow restoration. Besides, the ischemic state-space metrics were positively correlated with the pre-occlusion baseline appearance. Stroke patients exhibited impaired temporal variability in the affected ischemic hemisphere. The state-space analysis revealed damaged CBF temporal variability during cerebral ischemia and predicted baseline-ischemia connections.