Changes in the cerebral metabolic rate of oxygen consumption (CMR02) produced by neuronal activity are directly related to the energetics of brain tissue function. These changes contribute to the blood oxygenation level dependent (BOLD) fMRI signal and have been partly responsible for the extensive use of BOLD fMRI in multi-disciplinary studies of brain function. Determining the magnitude and dynamics of CMR02 responses from BOLD fMRI data has been of great interest not only to unravel the underpinning of the BOLD response, but also in the understanding of brain function. The goals of this proposal are to determine the dynamic changes in CMR02 elicited by neural activation using fMRI data and investigate whether the assumption of instantaneous oxygen transport and consumption is valid for this purpose. To this end, non-invasive and invasive measurements of CBF, cerebral blood volume (CBV), tissue oxygen tension (PO2tiss). optical imaging of intrinsic signals (OIS) and BOLD measurements will be acquired using MRI (9.4 Tesla scanner) and non-MRI methodologies in a well-established rat somato-sensory model. As a result of this proposed project, a method to determine the dynamic changes in CMR02 using fMRI data will be developed and validated. These methods can be used in the clinical setting to assess tissue viability and function in the brain as well as other organs. ? ? ?
