Dear Natalia,
> I have a question concerning the peak of activation. When you compare the
> coordinates of peak of activation in a region between sessions how much can
> differ the coordinates so that I can still say that the activation observed
> is the same. I’m looking only at the activation in anatomical ROIs ( define
> with Anatomy Toolbox) so I know that the coordinates I extract belongs to
> the same region but can I say that for example -41 -21 59 is the same as -14
> -32 71? Is there any good rules?
I don't think there are any simple rules that work for all regions —
it depends on what you mean by "region" in the phrase "same region".
For example, is it important that two regions are in "motor cortex"
(i.e. anywhere in the precentral gyrus)? Or is it actually important
that they correspond to some subdivision—say, relating to foot
movements? The specificity of the inference you are making determines
how close is "close enough".
One other point is to consider the extent of the activation, in
addition to the peak. Even though the peaks may differ, if most of the
mass of the clusters overlap, I would be much more convinced that
these are reflecting the same underlying neural activity.
Regardless, a good start is to constrain/identify your regions using
anatomical ROIs, as you have done. So, I think you would clearly be on
safe ground to say these are in the same (broad) anatomical region. As
to whether this is good enough for your study, I don't think there is
an easy answer.
Hope this helps! Good luck!
Best regards,
Jonathan
--
Dr. Jonathan Peelle
Center for Cognitive Neuroscience and
Department of Neurology
University of Pennsylvania
3 West Gates
3400 Spruce Street
Philadelphia, PA 19104
USA
http://jonathanpeelle.net/
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