Hi Freesurfers,
I have two unrelated questions.
1. I want to pre-whiten some functional data without running a GLM on them (we're going to run the GLM in matlab). It looks like fsfast does autocorrelation correction as a part of the selxavg3-sess wrapper. I tried poking around on the wiki and mailing archives, but I can't find how to pre-whiten the data without running a GLM. Is there a straightforward way? If not, I guess we could just do it in matlab.
2. Separately, we're bringing some volume masks to the surface and are preprocessing them with dilation and erosion to clean them up. We're trying to get a sense of how much is a reasonable amount to dilate and erode by, and it would be helpful to know about how far apart the adjacent surface vertices are. Roughly, what's the mean distance between adjacent vertices?
Thanks in advance.
Best, Alex