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Dear all, Currently I'm doing the VBM to compare a group of target subjects (Group A) with control group (Group B). We found that the peripheral gray matter at a particular area of the brain in Group A was significantly larger than that in Group B, using the contrast of Group B > Group A. Interestingly, when we used the contrast of Grooup B < Group A, the boundary of gray matter and white matter around the same area of the brain showed significant difference. Considering these results on gray matter only, it seemed to be conflicting. Originally, we thought that it might be due to the white matter difference so that the difference was shown at the boundary of gray matter and white matter. However, after we did the analysis on the segmented images of white matter, no difference was found around that area at all. I would like to ask whether there is(are) any other factors which may give the similar conflicting findings? Is it possible that it is an inherent problem of using VBM in segmentation that the white matter is not segmented properly? Please advise. Phoebe.