Table 2.
Head motion correction strategies investigated in the current study.
| Correction strategies | Descriptions |
|---|---|
| INDIVIDUAL-LEVEL | |
| Preprocessing-stage: motion was corrected during preprocessing | |
| Rigid-body 6 | Regress out 6 head motion parameters |
| Friston 24 | Regress out 6 head motion parameters, 6 head motion parameters one time point before, and the 12 corresponding squared items (Friston et al., 1996) |
| Friston 24 + scrubbing | Identifying “bad” time points using a threshold of FD (Power) >0.2 mm as well as 1 back and 2 forward neighbors as done in Power et al. (2013), then modeling each “bad” time point as a separate regressor in the regression models |
| Polynomial regression | The difference in correlation values (Δr) were calculated between the r-values acquired in Strategy 2 (Friston 24) and those in Strategy 3 (Friston 24 + scrubbing). A 5-degree polynomial model was used to fit Δr values on Euclidean distances, and then these fitted Δr values were regressed out from the original r values (Fair et al., 2012) |
| Connection estimation-stage: motion was corrected during connection estimation | |
| Graphical lasso | Using graphical lasso to estimate the partial correlation instead of full correlation |
| GROUP-LEVEL | |
| Connection-stage: the following motion-related parameters were regressed out from each connection before topological parameter calculation | |
| Mean iFC regression | Whole brain mean iFC |
| Motion regression | Mean FD |
| Mean iFC + motion regression | Both mean iFC and mean FD |
| Topological parameter-stage: the following motion-related parameters were regressed out from each topological parameter after their calculation | |
| Mean iFC regression | Whole brain mean iFC |
| Motion regression | Mean FD |
| Mean iFC + motion regression | Both mean iFC and mean FD |
| Both stages: the following motion-related parameters were regressed out from each connection before topological parameter calculation, as well as from each topological parameter after their calculation | |
| Mean iFC regressed | Whole brain mean iFC |
| Motion regressed | Mean FD |
| Mean iFC + motion regressed | Both mean iFC and mean FD |
FD, framewise displacement; iFC, intrinsic functional connectivity.