Hi Ken,

Avg: average cortical thickness between time-points
Rate: rate of change of cortical thickness
pc1: rate of change wrt. the first time point
spc: rate of change wrt. average thickness

You can find more info about these in this Longitudinal Tutorial: https://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/LongitudinalTutorial

Best,

Avnish

From: freesurfer-bounces@nmr.mgh.harvard.edu <freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of KennethSPrice <KennethSPrice@protonmail.com>
Sent: Sunday, February 26, 2023 10:41 PM
To: Freesurfer support list <freesurfer@nmr.mgh.harvard.edu>
Subject: [Freesurfer] What's the difference between pc1 and spc (glmfit)

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Hey Freesurfers,

I'm running a longitudinal study and have multiple outputs in my results. What's the difference between the "pc1" files and the "spc" files? Also what do the "rate" and "avg" files represent? Any response would be greatly appreciated!

Thanks,

Ken

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