White Matter BOLD signals as a Biomarker of Aging
Brain activity requires higher rates of oxygen delivery and blood flow, which increase BOLD (blood oxygenation-level dependent) signals that are detectable by functional magnetic resonance imaging (fMRI). BOLD signals have usually been associated with activity in the gray matter (GM) of the brain - where neuronal cell bodies reside. Growing numbers of studies have detected BOLD signals in white matter, the bundles of nerve fibers (axons) that transmit signals. In our previous studies, we have demonstrated that resting-state BOLD signals in specific white matter areas were strongly correlated with others, and WM functional networks can be identified by grouping areas that exhibit similar BOLD signals. In addition, compared to GM, the WM exhibits distinct BOLD time courses revealed by their power spectral patterns. However, there have been no comprehensive investigations into how the WM BOLD signals or network metrics are influenced by aging. Here we aim to investigate the age-related changes in WM BOLD at three levels including the network, vascular and pathological levels to detect unique functional biomarkers in WM that could predict aging. This 36-month project will be the first work that investigates the aging-related change in WM BOLD. Findings from this work will add to the existing understanding of functional changes in GM and provide novel insights into the fundamentally unique vascular-functional-pathological role of WM in the aging brain.