Significance
Cerebral metabolic rate of oxygen (CMRO2) consumption is a key physiological variable that characterizes brain metabolism in a steady state and during functional activation.
Aim
We aim to develop a minimally invasive optical technique for real-time measurement of CMRO2 concurrently with cerebral blood flow (CBF).
Approach
We used a pair of macromolecular phosphorescent probes with nonoverlapping optical spectra, which were localized in the intra- and extravascular compartments of the brain tissue, thus providing a readout of oxygen gradients between these two compartments. In parallel, we measured CBF using laser speckle contrast imaging.
Results
The method enables computation and tracking of CMRO2 during functional activation with high temporal resolution (∼7 Hz). In contrast to other approaches, our assessment of CMRO2 does not require measurements of CBF or hemoglobin oxygen saturation.
Conclusions
The independent records of intravascular and extravascular partial pressures of oxygen, CBF, and CMRO2 provide information about the physiological events that accompany neuronal activation, creating opportunities for dynamic quantification of brain metabolism.