[Freesurfer] comparing two conditions with disproportionate number of trials

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

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Hamdi Eryilmaz, PhD

Massachusetts General Hospital A.A. Martinos Center for Biomedical Imaging Brain Genomics Laboratory 149 13th St, Charlestown, MA 02129 Phone: +1 617 643 7462tel:%2B1%20617%20643%207462