Hello, There have been numerous posts recently related to the creation of a study specific "average subject". I have a question about the purpose/motivation of this for surface-stream analysis/visualization that I was hoping someone could clarify.
Specifically, my understanding is that the annotation/labels for any derived study specific average subject are determined by the "buckner40" gcs file (for the case of the desikan atlas). And similarly, the average surface (e.g., white, pial) and curvature-format files (e.g., curv, sulc, thickness) are registered across subjects via sphere.reg, which is determined by ?h.curvature.filled.buckner40.tif?
So, since the annotation and registration for any study specific "average subject" is going to be determined by the "buckner40" set of subjects regardless of the specific subjects in a particular study, what is the purpose, advantage, or necessity for creating a study specific average subject? Or stated differently, since the whole FS approach for registering surfaces (and by extension parcellating the cortex) is based on the assumption that the "buckner40" set of subjects is an appropriate registration and parcellation target for ALL studies, what is the point of creating a study specific average rather than using the default 'fsaverage' (which has the advantage of being created from the same set of 40 subjects that drive the registration itself)?
Please help me understand what I'm missing here.
thanks, Mike H.
P.S. Am I correct in presuming that the same 40 subjects were used for the Desikan GCS atlas and for deriving the spherical registration (.tif) target?