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diaz
BIAC Alum
USA
212 Posts |
 Posted - Apr 21 2011 : 1:48:40 PM
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i think you can.
We're trying out some resting state analyses we're using an 8mm seed in DMPFC and testing for voxel wise correlations. We're seeing an incredible amount of activation (i.e., the entire brain). Some background info:
- We've included wm and csf regressors, and our time series is orthogonalized wrt these two regressors
- we're using 5mm smoothing kernal
- we're using mixed flame 1+2 analyses, cluster correction p<.05
- we've incorporated filtering
Any thoughts on why we would see so much activation? |
Michele T. Diaz, Ph.D.
Associate Director
Brain Imaging and Analysis Center |
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clithero
Junior Member
37 Posts |
Posted - Apr 21 2011 : 1:57:35 PM
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Hi Michele,
So, your model has just three regressors?
Did you include a regressor for global signal?
Whenever I've done resting state analyses, the global regressor will typically result in a map like you have posted.
John |
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diaz
BIAC Alum
USA
212 Posts |
Posted - Apr 21 2011 : 3:30:11 PM
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| Thanks for the feedback - we haven't tried that yet. We hadn't included a global signal regressor (advice from Gary Glover) because apparently including a global signal regressor can sometimes enhance deactivations (e.g., chang and glover, 2008). But, I think this is an issue worth reconsidering since we're most interested in the (positive) activations and clearly the specificity of the current analysis is lacking. |
Michele T. Diaz, Ph.D.
Associate Director
Brain Imaging and Analysis Center |
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Can you have too much activation?
