Hi there!
I was hoping you could help me with the following 'problem' I am experiencing.
Short background: I compared volumetric brain characteristics as output from FreeSurfer parcellations and segmentations between 3 groups, by extracting the volumes per anatomical label from FreeSurfer and analyzing these in SPSS. In SPSS I did a mixed-model analysis, and performed subsequent Benjamini-Hochberg FDR correction for multiple comparisons.
At the moment, I want to make brain maps (because this is a nice way to visualize the data and a reviewer suggested it). However... I believe I end up with only being able to use the uncorrected maps? When I perform an FDR-correction (or MonteCarlo, or clusterwise) in FreeSurfer all the group differences disappear. Unfortunately there is nobody that I can consult on this matter in my lab, thus I really hope someone here can help me? Personally, I think that the difference in the presence (SPSS) versus absence (FS) of groups effects is due to the correction method. I believe that in FreeSurfer I apply a whole brain multiple comparison correction, while in SPSS I merely apply a ROI-based FDR-correction I in SPSS (because I look at volume per label).
However, I am not sure if this is indeed (theoretically) sound? Could anyone advise me? Is there a way I could visualise my own (SPSS) results? If more info is needed please do say so, and I will provide it!
Thank you very much for your time and reply! Best, Siri