The effects of spatial smoothing and z-transformation upon spatial-map-vs-SSRT correlations.

<p>The <i>negative</i> spatial-map-vs-SSRT correlation maps were thresholded at <i>p</i><0.05 (TFCE corrected for multiple comparisons across space, and for two-sided tests, but not corrected across multiple RSNs). <i>Non-Z-Map</i> indicates SSRT correlations on the spatial maps produced directly by dual-regression, and <i>Z-Map</i> indicates the correlations produced by the z-transformed version of these spatial maps. <i>No Smooth</i> indicates SSRT correlations based on the unsmoothed (i.e., only the 5-mm FWHM smoothing at the preprocessing stage) spatial maps, and <i>10-mm smooth</i> indicates the SSRT correlations based on the spatial maps additionally smoothed with a Gaussian kernel of FWHM 10 mm. The correlation maps were superimposed on their respective <i>group-mean</i> spatial maps obtained by Group-ICA and then on the MNI152 template. The <i>group-mean</i> spatial maps were provided here to show whether the significant regions lie within or outside the group-level RSNs. Red-yellow indicates significant regions in the <i>group-mean</i> spatial map, blue indicates significant spatial-map-vs-SSRT correlations that do not overlap with the group-mean map, and green indicates regions of overlap. The results were based on components corresponding to primary-medial (high eccentricity) visual networks, namely, component No. 14 from the 27-component analysis and component No. 54 from the 70-component analysis. The spatial-map-vs-SSRT correlations based on the z-transformed and 10-mm smoothed components were also shown though no significant voxel was observed. It can be seen that a greater number of significant voxels, if any, could be detected based on non-z-transformed and 10-mm smoothed spatial maps.