Hi Karry
painting is done by mri_vol2surf and you can use it to specify how you want the sampling to be done. We typically sample the volume halfway our from the gray/white boundary, or sometimes a bit lower to avoid vascular artifacts at the pial surface. That said, it is quite flexible and you can use it to sample however you wish (e.g. average over the bottom third of cortex, etc....). When we sample we don't inspect the value, just grab it from the volume and assign it to the surface so if there are significant cluster that aren't intersected by the sampling band you specify they will not appear on the surface.
cheers Bruce
On Sun, 2 Sep 2012, keepmoon wrote:
Hello everyone, I just read the information about "paintig SPM results onto Freesurfer" (http://surfer.nmr.mgh.harvard.edu/fswiki/SpmPainting).%C2%A0 It shows how to painting SPM results from statistic step (ex. spmT.img) to surface space. I tested the procedure and it worked. But I don't understand what is displayed on Freesurfer surface. Are all the significant differences from SPM statistic results are displayed on this surface? or some part of t values are displayed (which part)? As cortical thickness displayed on surface, each thickness value is painted on each vertex. But here t-value image from SPM is volume image, how to paint it on surface? Someone could give a little detailed explaination?? Thanks in advance Karry