Research Article

Effective Preprocessing Procedures Virtually Eliminate Distance-Dependent Motion Artifacts in Resting State FMRI

Figure 6

Cross-correlation matrix between the regressors. The correlation coefficients were averaged over all subjects ( ). MO represents the six regressors containing rigid-body motion parameter estimates (three translations and three rotations). GS is the average RS-FMRI time series over all voxels in the brain mask. WMe and LVe refer to the RS-FMRI time series averaged within eroded white matter and eroded lateral ventricles, respectively. Prime marks (′) indicate the first differences of the regressors. The regressors were obtained from the time series that were despiked, slice-timing corrected, and then volume registered, and spatial smoothing was not applied to avoid mixing signal across different brain-tissue masks.