Dear Freesurfer users --

I'm trying to display a SPM t map (i.e., normalized in SPM8 standard template) in freesurfer inflated surface for paper figure.

So, once projecting the SPM t maps into freesurfer template (e.g., rh.inflated), I'm wondering how I can best find out freesurfer's threshold that matches the original threshold (e.g., t>4 in SPM8) given that the values in every voxel were interpolated to a different value across neighboring vertices during surface reconstruction (e.g., 4 in one voxel is mapped onto 3.92 or 4.1).

Is there any rule of thumb to figure out a corresponding value between 3D (voxel) and 2D (vertex)?

I'm sure that I'm not the only one dealing with this problem and sharing any of your wisdom will be greatly appreciated.

-ysl