Friday, May 27, 2022 • 10:05–11:05 am (CT) • Light Hall, Room 208
Keynote presenter: John Gore, Vanderbilt University Medical Center
Blood oxygenation level dependent (BOLD) contrast in MR images has for >30 years been exploited for detecting localized neural activity in the cortex using functional MRI (fMRI), and is an essential tool for mapping brain function. In addition, correlations between fMRI signals in a resting state are interpreted as depicting functional connectivity between regions. While BOLD signals have been reliably detected in grey matter (GM) in a very large number of studies, such signals have rarely been reported from white matter (WM). However, although BOLD effects are weaker in WM, using appropriate detection and analysis methods they are robustly detectable both in response to stimuli and in a resting state. Moreover, resting state correlations between voxels in WM appear to be anisotropic but allow the construction of functional correlation tensors that quantify this correlational anisotropy. WM BOLD signals in specific tracts change in response to stimuli and are modulated by tasks in much the same way as GM. Of particular significance for data analyses, the hemodynamic response function varies along and between WM tracts and is different from that in GM, so that conventional general linear models are inappropriate. Resting state correlations between segmented WM tracts and parcellated GM volumes provide new structure-function relationships in the brain, and changes in these appear to be biomarkers of pathologies such as neurodegeneration. The need for novel analyses incorporating multi-way correlations that include both WM and GM is clearly indicated. This presentation will summarize some of our recent studies that provide evidence that BOLD signals in WM are related to brain functional activity and will highlight new opportunities for the analysis and interpretation of fMRI data.