Per-Subject and Per-Brain-Region Hyperoxic (HO) and Hypercapnic (HC) BOLD Calibration to Investigate Neurovascular Metabolism Coupling Linearity

Clarisse Ildiko Mark¹, G. B. Pike¹

Estimates of the coupling relationship (n) between changes in cerebral metabolic rate of oxygen (ΔCMRO₂) and blood flow (ΔCBF) under neuronal activation, key in interpreting BOLD results, are highly sensitive to variability in individual subjects BOLD calibration (M)-values and brain regions. We thereby sought to acquire precise calibration data under robust control of HC and HO levels, together with visual stimulation of varying frequency and voluntary motor tasks. Based on low-variability M-values, our findings demonstrate a tightly coupled and linear flow-metabolism relationship in the visual cortex, an indication that oxygen demand from activated neurons across visual-frequencies is met by oxidative metabolism.