When you say in the corpus callosum, do you mean in WM? The surface-based analysis is only for cortical GM. If you mean in GM near the CC, then the analysis is appropriate. The projfrac parameter sets the sampling location between the white and pial surfaces where 0.5 means half way.

Dear FS experts,

I am working on surface based analysis using freesurfer. I want to inquire about the flag "projfrac" in the command "mris_preproc"

 

I ran voxel wise analysis including the same subjects. I found differnce between the groups in areas close to the corpus callosum. I want to get the same results using surface based analysis. If I use the projfrac=0.5 is this able to show the same results that I got in voxel wise analysis at the level of the corpus callosum. Do I need to use differnt number for projfrac ?

 

Thank you for any advice.

 

Best,
John

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