> why ICBM use 8mm FWHM smoothing filter?
The template images and tissue probability maps in SPM are smoothed by 8mm in
order to account for additional inter-subject variability. The data
themselves were generated from relatively young healthy subjects, so
additional smoothing may have helped. Smoothing also means that the various
Taylor series approximations required by the intersubject registration worked
rather better. The tpm/*.nii images used by the SPM5b segmentation routines
are unsmoothed.
Best regards,
-John
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