It is hard to say. If one hemi has significantly more activation than the other, then the one with more activation will have a lower threshold. Given that the hemis are about the same, I'm not sure what to say. The FDR is dependent up on all the voxels, not just the ones you happen to be looking at above some threshold, so it is possible that the hemis differ on the less significant voxels.

doug

On 08/26/2013 03:57 PM, Emily Boeke wrote:

Hi Freesurfers,

I have a contrast that produces comparable activation in both hemispheres. But when I set the threshold using FDR in the Configure Overlay Display window, the threshold is set to 5.1 for left hemisphere and 3.3 for the right hemisphere, leaving significant clusters only in the right hemisphere. Does someone know why the FDR threshold would be so different between the two hemispheres?

Thanks! Emily _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer