On 01/19/2013 03:18 PM, Alex Kell wrote:
Hi Freesurfers,
I have two unrelated questions.
- 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.
FSFAST uses an AR1 model. It computes the AR1 from the residuals (thus needing to run the GLM first). The voxel-wise AR1 is spatially smoothed, then binned into 10 bins. All the voxels in each bin are then analyzed in the same way.
- 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?
About 1mm doug
Thanks in advance.
Best, Alex
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