Functional Diffusion Tensor Imaging: Measuring Task-Related Fractional Anisotropy Changes in the Human Brain along White Matter Tracts (original) (raw)
Figure 6
Positively correlated fDTI results for subject #5 computed in three different ways.
(a) The original active tracts found based on changes in FA using the sign-test (See Figure 1). (b) Analysis of the same data set using conventional t-statistics as in ROI/VOI based fMRI. For each voxel in the fDTI scan a multiple regression was carried out. Two regressors were used, one encoding for the stimulus (0/1) and the other representing possible linear scanner drift. Each tract that was tested for activation was considered active if the mean of the stimulus regressor values of the voxels in the tract was found significantly higher than zero using a one-sided Student's t-test (p<0.05; Bonferroni corrected for the number of tested tracts). (c) Active tracts based on changes in the radial diffusion component using the sign-test. The three different methods yielded very similar activation patterns. The similar results for (a) and (b) indicate that the results do not depend on the chosen statistical method. The similar results for (a) and (c) indicate that the measured signal change stems predominantly from a change in diffusion in the radial direction.