Hyperoxia Modulated Evoked Cerebral Blood Flow in the Human Motor Cortex: Measured with LL-FAIR ASL

Paula L. Croal¹, Emma L. Hall¹, Ian D. Driver¹, Penny A. Gowland¹, Susan T. Francis¹

Local CBF (LCBF) is currently thought to increase on cortical activation to meet an increased demand in oxidative metabolism. However, animal literature suggests that this increase is dominated by a change in the vascular reactivity, as the LCBF response is higher with hyperoxia. This study measures the LCBF response in the human motor cortex on hyperoxia using LL-FAIR-ASL. A trend was seen, with hyperoxia increasing the LCBF response and reducing transit times to a greater extent than normoxia. This finding raises questions as to whether the role of functional hyperaemia is driven by changes in metabolic demand or vasculature reactivity.