FIG. 9.

Histograms of the Spearman's rank correlation, across subjects, of the mean volume-to-volume motion (Enorm) and the functional connectivity for all pairwise connections from 230 ROIs, for different sets of nuisance regressors to reduce motion-related signal changes: J = JumpCor regressors, W = average signal over eroded white matter and its temporal derivative, C = average signal over ventricular CSF and its temporal derivative, G = average signal over the whole (global) brain and its temporal derivative, M = estimated realignment parameters. (a) Without any nuisance regression (none, black line), most connections are highly correlated with motion. When JumpCor regressors are removed (red line), the correlation with motion is significantly reduced, being more centered around zero. The correlation is further reduced by regressing out motion, white matter, CSF, and global signals, and even further reduced by regressing out these nuisance regressors and the JumpCor regressors. Null distribution is obtained by permuting the mean framewise displacement across subjects and then recomputing the Spearman's rank correlation. (b, c) Histograms for different thresholds for what is considered a “jump.” (b) after regressing out only the JumpCor regressors; (c) after regressing out the JumpCor regressors (J), average signal over eroded white matter and its temporal derivative (W), average signal over ventricular CSF and its temporal derivative (C), G = average signal over the whole (global) brain and its temporal derivative (G), and the estimated realignment parameters (M). Reducing the jump threshold reduces the correlation with motion when only the JumpCor regressors are removed. When all of the nuisance regressors are removed, different jump thresholds have only a small effect. ROI, region-of-interest. Color images are available online.