[Freesurfer] significance thresholds and multiple comparisons corrections

Hi FreeSurfer groupers.

I have been using FreeSurfer since v3.0.2, but still have some questions about the group analysis pipelines. I have used both QDEC and the previous manual method using glm_fit.

Questions about QDEC:

1. What are the guidelines for setting significance thresholds, by adjusting the color thresholds? 2. Should the FDR correction for multiple comparisons that is is the GUI be used?

Previously, we used mri_glmfit to correct for multiple comparisons, using the mc-z-z- monte carlo simulation method. We would then report the p-values obtained from the clustering.

My main question is what is the best direction to take after using QDEC, i.e. how to correct for multiple comparisons? Also, are there any advantages/disadvantages to using QDEC/glm_fit, for example circumstances where one would be better to use. (For instance, you can have more factors when using glm_fit)

I appreciate any help or suggestions that anyone has to give, for I am trying to finish two papers using freesurfer. Also, thanks for developing QDEC, for it makes second level analysis easier to set up.

Thanks,

- Judith S.