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. Author manuscript; available in PMC: 2014 Jan 20.
Published in final edited form as: Neuroimage. 2013 Mar 15;76:183–201. doi: 10.1016/j.neuroimage.2013.03.004

Table 1.

Summary of objectives, materials, methods and key novel findings.

Objective Analytic Method Data Employed Key Novel Findings
  • 1

    Demonstrate Regional Variation in the Impact of Motion on the BOLD Signal (Figures 1, 2, S1, S2, S3)

  • Calculate the correlation between BOLD signal and voxel-specific head motion and then perform one-sample t-test.

All datasets
  • High motion datasets exhibited more pronounced negative motion-BOLD relationships (esp. prefrontal areas).

  • Low motion datasets exhibited more pronounced positive motion-BOLD relationships (esp. primary and supplementary motor areas).

  • 2

    Evaluate the Ability of Motion Correction Strategies to Decrease the Impact of Motion on the BOLD Signal at Individual-Level (Figures 3, 4, S4)

  • After applying the individual-level motion correction strategies on the functional data (after realignment), calculate the correlation between corrected BOLD signal and voxel-specific head motion.

  • Calculate the mean positive correlation and mean negative correlation as summary measures for each participant, and then perform paired t-test to compare strategies.

Cambridge Adults (n = 158; 18 participants removed due to motion)
  • Only ‘scrubbing’ (FD < 0.2mm) removed negative motion-BOLD relationships.

  • Positive motion-BOLD relationships tended to cluster in primary and supplementary motor areas and remained even after scrubbing, thus may reflect to motion-related neural activity.

  • 3

    Evaluate the Ability of Motion Correction Strategies to Decrease Residual Relationships Between Motion and R-fMRI Metrics at Group-Level (Figures 5, 6, S5S10)

  • Calculate R-fMRI metrics after motion correction strategies, and then evaluate their correlation with motion across participants.

  • Wilcoxon signed-rank test were used to test the distribution of residual motion effects (absolute correlation) across motion correction strategies.

Cambridge Adults (n = 158)
  • None of the individual-level motion correction approaches successfully bypass the need for group-level correction for inter-individual differences in R-fMRI related to motion.

  • Z-standardization on subject-level maps reduced relationships between motion and inter-individual differences

  • 4

    Examine the Influence of Global Signal Regression (GSR) on the Impact of Motion on the BOLD signal and R-fMRI metrics (Figures 7, S11)

  • Repeat the analyses in objective 4 and 5, taking in account GSR as well as WM/CSF signal regression.

Cambridge Adults (n = 158)
  • GSR introduced negative motion-BOLD relationships at individual level.

  • However, GSR was highly effective in removing inter-individual differences related to motion.

  • 5

    Examine the Impact of Motion and Motion Correction Strategies on Test-Retest Reliability (Figures 8, S12)

  • Calculate R-fMRI metrics after motion correction strategies, then evaluate the test-retest reliability via intra-class correlation (ICC).

  • Wilcoxon signed-rank test were employed to compare the reliability across motion correction strategies.

NYU TRT (high motion dataset [n = 11] vs. low motion dataset [n = 11])
  • Motion appears to reduced test-retest reliability for correlation-based metrics

  • Motion did artifactually increase the reliability of frequency-based metrics (ALFF >> fALFF); correction approaches reduced these increases.

  • 6

    Compare Framewise Displacement (FD) Metrics (Figure 9)

  • Plot the difference between FDvol and meansp FDvox as a function of meansp FDvox for all time points and all participants.

  • Plot the temporal mean of FDvol (mean FDvol) and temporal mean of meansp FDvox (mean [meansp FDvox]).

Cambridge Adults (N = 176)
  • Overall, there was high concordance among volume-based metrics of FD.

  • Failure to account for rotation can lead to substantial underestimation of FD.

  • The metric by Jenkinson et al. (2002) uniquely accounted for regional variation in motion.