Dear FreeSurfer experts,

I would like to compare surface area in a vertex-by-vertex fashion across two subject groups. There has been some discussion already on the mailing list and it seems that areal expansion is a better measure than simply area.pial for doing so.

I also remember reading that when the data is converted from native space to a template (e.g. fsaverage), the values are automatically transformed to areal expansion measures.

Please could you let me know if the output of –qcache (e.g. lh.area.pial.fsaverage.mgh) contains the area values (i.e. average area across triangles touching vertex) or areal expansion values. I believe these values are also compared in qdec.

Many thanks, Christine

----------------------------------------------------------------------------------------- Dr. Christine Ecker Department of Forensic and Neurodevelopmental Science, PO50 Institute of Psychiatry De Crespigny Park, Denmark Hill London SE5 8AF

Phone: +44(0)207 848 0947 Email: christine.ecker@kcl.ac.uk -----------------------------------------------------------------------------------------