Hello, I am trying out a PPI analysis using FEAT for the first time and
have run into 2 questions:
(1) In the instructions that I have seen, there is an option for "make
zero" on the stats set up where you choose "interaction" for the 3rd EV,
but in my fsl gui there is only the option to check "demean". Is it OK to
check demean for both EV1 and EV2, and will it mean the same as what's
described in the on-line presentation (Centre for EV1 and mean for EV2).
(2) The task for this experiment involves 3 conditions, which are viewing
fixation, viewing neutral faces, and viewing fear faces. I'm not sure how
to set up the contrasts in FEAT since the examples are usually for on-off
paradigms. This is a problem that I also am running into as I try to run
the traditional analysis of activation between conditions and between
patient groups.
Thanks, Katie
Kathryn R. Cullen, M.D.
Assistant Professor
University of Minnesota Medical School
2450 Riverside Avenue
Minneapolis, MN 55454
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