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Dear Dr. Ashburner and SPMers: We had a methodology question about the VBM procedure of Goode et al. We are at the point where we apply the warps to whole brain images, followed by segmentation. Is it valid to apply the .mat files obtained from the gray matter images to whole brain images, segment, and then do statistics on gray and white matter maps? Put another way, is it valid methodology to apply statistics to white matter maps normalized with the gray matter image to gray matter template normalization parameters ? Or would it be better to normalize the whole brains separately, using the parameters from the gray matter image to gray matter template warp, and the white matter image to white matter template warp, and then segment the normalized images, and use use the gray and white matter maps derived from the warps of the same tissue type? Or does it even matter? Regards, Rob McClure