Fig. 13.
Regression of cortical signal from the striatum. The effects of regressing out the adjacent cortical signal from the striatum are shown with the full sample of 1,000 subjects. A–D: posterior striatum (y = −8). E–H: anterior striatum (y = 12). First 2 columns show the 7-network parcellation (A, E) and an fcMRI map of a proximal insula seed region (B, F) with no cortical signal regression from the striatum (see methods for seed region coordinate). Third and fourth columns show the 7-network parcellation (C, G) and fcMRI maps of the same seed region (D, H) with regression of cortical signal from the striatum (not applied to cortex). Note how the parcellations are dominated by the network labeled by violet. When regression is applied, a more plausible parcellation results. The contrast between the functional connectivity patterns within the striatum before (e.g., F) and after (e.g., H) regression of adjacent cortical signal illustrates that bleeding of signal from cortex to striatum is mitigated but not fully removed. Signal bleeding minimally affects the major portions of the caudate and ventral striatum. Parcellation estimates within the putamen are less certain.