| in the spm_defaults.m, the default voxel size is apparently 3mm but the
| voxel size of normalized images is set to 2mm of isotropic dimensions.
| Does this account for part of the smoothing by normalization? Is it
| reasonable at all to have the normalized images resampled to a voxel
| size below the acquisition? Does´t that introduce statistical errors to
| the inference accuracy level?
By default, the voxel sizes of the spatially normalised images should
be 2mm. This is on line 211 of spm_defaults.m:
sptl_Vx = [2 2 2]; % 2mm x 2mm x 2mm
If you have an spm_defaults.m file that says differently, then check
to see if this is the one that SPM99 is using by typing the following in
Matlab:
which spm_defaults
It should be OK to write spatially normalised images at a higher resulution
as the Gaussian field theory should be able to account for the correlation
between neighbouring voxels.
Best regards,
-John
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