Global mean regression removes all voxels?

Submitted by nertman on Fri, 05/17/2013 - 17:25

Hi, I have been using DPARSFA for preprocessing and it has been working very well so far. I tried to remove the Global Signal nuisance regressor, but after doing so my data has no voxels left -- i.e., when I enter it into a first-level model in SPM, and estimate the model, I get this popup message:
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No inmask voxels - empty analysis!
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And this command line error message:
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Reference to non-existent field 'xVol'.
 
Error in spm_getSPM (line 243)
XYZ  = SPM.xVol.XYZ;                %-XYZ coordinates
 
Error in spm_results_ui (line 263)
        [SPM,xSPM] = spm_getSPM;
 
Error while evaluating uicontrol Callback
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I've had the same thing happen regardless of the level of preprocessing that has been done. When I skip the global signal regression everything runs fine. What might be the problem?

Forums:

YAN Chao-Gan

Tue, 05/21/2013 - 18:12

Task fMRI?

If the global signal is highly correlated with your task regressor, then you may get no results in SPM's first-level analysis.

nertman

Tue, 05/21/2013 - 18:37

 Thanks for your reply. It is resting state data.

YAN Chao-Gan

Tue, 05/21/2013 - 19:02

So what do you want to do with SPM's first-level analysis?

nertman

Wed, 05/22/2013 - 18:16

 The global signal regression removes all voxels whether I'm looking at resting data or task-based data...what do you recommend I do to solve this?

YAN Chao-Gan

Mon, 05/27/2013 - 15:09

Sorry, I still can not get your point. Please see http://www.restfmri.net/forum/FAQ #4 is relevant to your question.