Hi Bruce,
Thanks a lot for your reply.
- The surface area of fsaverage is less than any individual, so you *definitely* don't want to use it. You should map the ROI back to individuals and compute it in the native space.
I have two follow-up questions:
1) Do .pial.avg.area.mgh and/or .white.avg.area.mgh then store the mean native space surface areas for the individuals that were used to create fsaverage, and can I use these values to approximate the surface area of my ROIs then?
2) Do the avg.area files also exists somewhere for the half-thickness mid-surface? If not, does it make sense to approximate the mid-thickness surface area at each vertex by taking the mean of the corresponding pial.avg.area and white.avg.area entries?
Many thanks, Boris
cheers Bruce
On Wed, 11 May 2011, Boris Bernhardt wrote:
Hello Freesurfer-experts,
I just analyzed some FreeSurfer cortical thickness data that have been surface-resampled to fsaverage (using mris_surf2surf with -s fsaverage).
For the visualization and reporting of my findings, I have a two questions:
Is there anything that conceptually speaks against showing my results on non-inflated surfaces of fsaverage, such as the white matter surface, the pial surface, or even a mid-surface model?
I have a couple of ROIs defined on the surface of fsaverage and want
to report the surface area of a given ROI in mm^2. Should I calculate the area of a ROI directly from the given surface of fsaverage, or to take the area computations from ?h.pial.avg.area.mgh/?h.white.avg.area.mgh which represent the averages of the individuals that went into fsaverage.
I am asking because I was slightly unclear of the wiki-instructions: https://surfer.nmr.mgh.harvard.edu/fswiki/GroupAverageSurface suggests to use ?h.pial.avg.area.mgh;
on the other hand, the more recently edited http://surfer.nmr.mgh.harvard.edu/fswiki/FsAverage says that "The surface area of the new average subject (fsaverage) is that of a typical subject"
I am using freesurfer 4.5.0.
Hope my questions make sense and thank you very much for answering them, Boris
Boris Bernhardt, PhD Max Planck Institute for Human Cognitive and Brain Sciences Stephanstr. 1a, 04103 Leipzig, Germany
p: +(49) 341 9940 2658 e: bernhardt@cbs.mpg.de http://www.cbs.mpg.de/~bernhardt
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--- Boris Bernhardt Max Planck Institute for Human Cognitive and Brain Sciences Stephanstr. 1a, 04103 Leipzig, Germany
p: +(49) 341 9940 2658 e: bernhardt@cbs.mpg.de http://www.cbs.mpg.de/~bernhardt