[Freesurfer] Freesurfer Versions - Zeros in the Cortex

External Email - Use Caution

Hello,

We are looking at the vertex-wise thickness measures for participants within the fsaverage space. There are a number of indices within the cortex that have thickness values of 0 in the thickness.fsaverage.mgh surface files. In FreeSurfer version 5.1, those same indices no longer have thickness 0 in the corresponding rh and lh fwhm smoothed thickness surface files due to the smoothing effect. However, in versions 6 and 7.1.1, the indices with 0 values remain 0 even in the fwhm smoothed files. Do you know why it was chosen that smoothing should have no impact on zeros in the later versions of FreeSurfer? Also, if we are interested in impacting the zeros from the later versions, is there a methodology which you would recommend?

Thanks,

Daniel