Figure 6. Pre-regression relationships between mean compartment signals, the global signal, and ROI timecourses.

For all 160 subjects, the indicated correlations between the gray matter (GM), the white matter (WM), the ventricular (CSF), and whole-brain (GS) signals were calculated. Additionally, for 264 regions of interest, within-subject averages for the correlations of the 264 timeseries with the global signal were calculated, as well as the mean correlation over all possible pairwise correlations between the 264 ROIs. All timeseries are from demeaned and detrended data, as in Figures 3–5. The values in each subject are plotted as a function of mean FD value and RMS motion. Linear fits including all subjects (gray) or excluding outliers (black) are shown. Signal similarity, generally, is higher in subjects with more movement. Mean FD, generally, is a better predictor of signal similarity than RMS motion. Gray matter signal is highly correlated with the global signal.