I used to work with .nii files in SPM, but I've never encountered with .gii files.
These two types of files are not interchangeable.
.gii files represent surfaces.
.nii files represent volumes.
I read on the ResearchGate that CAT12 toolbox for SPM is best for working with this type of files.
I'm not sure what you can do in CAT with .gii files...
@CGaser?
"Error using spm_spm (line 652)
Please check your data: There are no inmask voxels."
Сan you tell me what does this mean?
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