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Comment
. 2013 Aug 1:76:439-41.
doi: 10.1016/j.neuroimage.2012.03.017. Epub 2012 Mar 13.

Steps toward optimizing motion artifact removal in functional connectivity MRI; a reply to Carp

Jonathan D Power  1 , Kelly Anne Barnes, Abraham Z Snyder, Bradley L Schlaggar, Steven E Petersen
Affiliations
Comment

Steps toward optimizing motion artifact removal in functional connectivity MRI; a reply to Carp

Jonathan D Power et al. Neuroimage. .
No abstract available

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Figures

Fig. 1
Fig. 1
(A) The two indices used to create temporal masks in Power et al. (2012) are shown for a single subject. On top in red is the framewise displacement (FD) measure, which indexes volume-to-volume changes in head position. Below in blue is the DVARS measure, which indexes RMS BOLD signal change across the whole brain from volume to volume. The DVARS measure was calculated for this subject's data before (light blue) and after (blue) functional connectivity processing. Dashed lines represent the thresholds used in Power et al. (2012) and the solid lines indicate the thresholds presently used within the Petersen/Schlaggar laboratory to maximally remove motion-contaminated data. (B) A histogram of the sizes of the periods of movement detected in Cohort 1 using the standard thresholds of Power et al. (2012), modified from Figure S8 of Power et al. (2012). Most movements last several contiguous TRs and many movements are quite long. (C) Regressions for the child and adult cohorts were performed without (uncensored) and with (censored) temporal masks. Two-sample t-tests comparing the beta maps in children and adults were performed. The images show the resultant p-values for the whole brain signal regressor without and with volume censoring. Many differences in beta maps between children and adults are eliminated or lessened when high-motion data is excluded from the regression. This result is typical of the other beta maps produced by other regressors (e.g., ventricular signal, white matter signal, etc.)
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References

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