Using the same settings as above I get images that seem to be processed badly (see above (2nd image)). I guess related to this is the message I get during preprocessing:
Warning: Matrix is close to singular or badly scaled. Results may be inaccurate. RCOND = 8.499165e-10.
Additionally, looking at the CovariablesSub_***.txt file, the covariates are close to zero. (I run into similar problems using nifti and analyze formated images, after normalization step using epi templates, as well as using the unified segmentation approach (and using SPM apriori / or segmented masks).
The image is normal after regressing out covariates. For each voxel, the temporal mean will be zero after nuisance regression, thus you will no longer see the difference in mean intensity among gray matter, white matter and CSF.
Also, you will see a clear boundary between voxels insider brain from those outside brain before regression. However, after nuisance regression, all the voxels were near zero, thus you will no longer see the boundary.
Most of the resting-state fMRI analyses (e.g., FC, ALFF, ReHo) were interested in the variation other than the mean, the temporal dynamics were still there within the "distorted" images.
CovariablesSub_***.txt file, the covariates are close to zero is because head motion usually is small. As long as they have variations, it should be OK.
YAN Chao-Gan
Mon, 11/24/2014 - 19:30
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Hi,
Hi,
Usually wannings can be ignored.
The rank of your covariate matrix is 27. Could you paste the nuisance setting here?
Best,
Chao-Gan
Ham
Tue, 11/25/2014 - 09:39
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Thank you so much for your
Thank you so much for your answer,
Do you think the preprocessing steps are reasonable or I will have a hard time with a reviwer?
Note I use the component correction method.
Best
YAN Chao-Gan
Mon, 12/01/2014 - 21:34
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Hi,
Hi,
I think this setting should be fine.
Best,
Chao-Gan
Ham
Wed, 12/03/2014 - 12:04
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Dear Dr. Yan,
Dear Dr. Yan,
Thank you so much!
Best,
Sharka
Thu, 01/22/2015 - 14:54
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Dear Chao-Gan
Dear Chao-Gan
Using the same settings as above I get images that seem to be processed badly (see above (2nd image)). I guess related to this is the message I get during preprocessing:
Warning: Matrix is close to singular or badly scaled. Results may be inaccurate. RCOND = 8.499165e-10.
YAN Chao-Gan
Thu, 01/22/2015 - 17:27
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Hi Diana,
Hi Diana,