Once the DMN component was identified for all subjects, we carried out two types of analyses based on the spatial map and component timeseries. For the spatial extent analysis, DMN components were entered into a higher level analysis performed using FEAT (fMRI Expert Analysis Tool), version 5.4 (http://www.fmrib.ox.ac.uk/fsl). Between-group differences were examined using an ordinary least squares simple mixed-effects model. Z statistic images were thresholded at Z>3.09 (p<0.001, uncorrected) and spatial extent of 25 voxels. We chose this liberal statistical threshold because we used a relatively novel analytic approach (independent component analysis) where we could not predict effect sizes in between-group comparisons, and because we studied difficult clinical populations. Our group N's were sufficient but modest, limiting statistical power to detect between-group differences. The between-group analyses were masked with the DMN statistical map of the first group (e.g. NC>BD comparisons masked with the NC group map and BD>NC comparisons with the BD group map). Figure 1 depicts the mean group DMN images from the higher-level analysis. An identical analysis was next carried out using the V1 template instead of DMN.
