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)

External Email - Use Caution

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

Sent with Proton Mailhttps://secure-web.cisco.com/1boPq8uQ-9H8Gy1fAGjjCB35J45SPTFBfkpwoo3x3bISPlramWjRzCkj2QOs1sJPXP1cbJUwKMOLlYD63YWzGU9EBm3Tw57AxAjRCgKMlnqytjyEa2NBjYg9nNhdMfD_6PqfocgNn4NPSqnlBOY40azvHRxibf1pMu7BXhgI2Z4ZGzJVQAD9JWcK9U0tcgibjH-xVdDPqj_CDaZkSZocd_lApusMm6LMj8q3GLVZ-30VKDEa-ctLWINE0ImupZ9hOoSI-w6qpE4s4ijyZUIogN4RSmOZRA0prTrDmZI-7VPxHAcLnUKHWDlXIGWhZ-6Fiy7jkRVqKgx1qOm23vSGspw/https%3A%2F%2Fproton.me%2F secure email.