Hi Yael,
I know even less about EEG than I do VBM, but this sounds suspiciously
like the problem that low variance (e.g. outside the head) can pull
the statistic peaks away from the actual signal peak.
See e.g. John's example at the bottom of this post:
http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind04&L=SPM&P=R307792&I=-3
and my (somewhat rashly heated) debate in this thread:
http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0603&L=SPM&P=R38777&I=-3
and most importantly, see if Matthias Reimold's toolbox helps solve
your problem:
http://homepages.uni-tuebingen.de/matthias.reimold/mascoi/description/
Hope that helps,
Ged.
Yael Weisberger wrote:
> Hello,
> We have been evaluating some EEG results using SPM. In many cases we
> noticed the significant effects SPM found was located on the edges(the
> boundaries of the head map) of our F-map. We added two images as an example.
> Is there something in the Random Field correction that might bias the
> results to prefer the edges of the map?
>
> Thanks,
> Yael.
>
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