 |
 |
You need to use the voxel size of the statistics image. If you have 3x3x5 original voxels and come up with 130 voxel extent, then you can't use 130 voxels if your image was resampled to 2x2x2. You'd need to rerun AlphaSim (or rather 3dClustSim) with the appropriate voxel size. Don't forget to use the mask.img image as well to constrain the search region. Best Regards, Donald McLaren ================= D.G. McLaren, Ph.D. Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School Postdoctoral Research Fellow, GRECC, Bedford VA Website: http://www.martinos.org/~mclaren Office: (773) 406-2464 ===================== This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is intended only for the use of the individual or entity named above. If the reader of the e-mail is not the intended recipient or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that you are in possession of confidential and privileged information. Any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited and may be unlawful. If you have received this e-mail unintentionally, please immediately notify the sender via telephone at (773) 406-2464 or email. On Thu, Aug 2, 2012 at 2:47 PM, Hongyu Yang <[log in to unmask]> wrote: > Hello List, > > I have some questions about group mask for Alphasim. > I use SPM8 for my fMRI data anslysis, and now I am trying to > do multiple comparison correction with Aphasim. I have finished > smooth measurement with 3dcalc and 3dFWHMx. But one quesiton > is not clear: For the group mask we need to use for correction, > do we need to use the original fMRI voxel size(3*3*5), or the voxel size after > normalize (3*3*3)? I found the two results changed a lot. If I used the resolution > after normalize, it was 230 voxels, but I got 130 voxels if I used my original > fMRI resolution. 230 voxels is very high and very difficult to get positive results. > Can you help me to explain this problem? > > Thanks, > Hongyu Yang > > ~~~~~~~~~ > Hongyu Yang, PhD > Research Specialist in Health Science > Pediatric Brain Research And InterventioN Center > Department of Psychiatry > 1747 West Roosevelt Road, M/C 747 > Chicago, Illinois 60608 > Phone: (312) 413-4622 > Fax: (312) 413-0063 > Email: [log in to unmask] > http://www.psych.uic.edu/brain-center