Dear FS experts,
I have a question about the way contrasts work in an event-related design. I am wondering if freesurfer is doing some sort of weighing when it compares two different conditions with incomparable number of trials. For example condition A is represented by 10
trials in the paradigm file, whereas condition B consists of 80 trials. In that case, for the contrast A>B does freesurfer compensate for the small number of trials in condition A? If so, could it lead to inflated activations? We suspected this as in our results,
the condition with fewer trials depicted strong activations.
Thanks very much for the tips!
Best,
Hamdi
--
Hamdi Eryilmaz, PhD
Massachusetts General Hospital
A.A. Martinos Center for Biomedical Imaging
Brain Genomics Laboratory
149 13th St, Charlestown, MA 02129