Hi,

I have a question about how to make surfaces in shape of inflated or white/pial (fiducial) surface for the fsaverage atlas. In my understanding, to make a population average surface from multiple individual surfaces, the surfaces should be first in shape of sphere. But, I'm not clear how can we obtain population average surface in shape of inflated and original white/pial surface which do not depend on specific individual. This is my question.

Freesurfer seems to have such surfaces like inflated.avg or white.avg. And from the logs for creating fsaverage (make_average_surface.log), it seems that this is done by averaging individual surfaces after being transformed into each type of configuration(inflated, white, etc...). But in that case, what was averaged for example in case of averaging inflated surface? 3D coordinate (x,y,z)? But if so, it will lose the topology of cortical surface.

If you have any answers or comments to this question, please give some advice.

Regards, Tomoyasu ++++ HORIKAWA Tomoyasu ATR CNS Dept. of Neuroinformatics