Figure 2.
Effects of motion correction on ICA components. (a) The predictability of the data, estimated by the diagonals of the Hat matrix, H = X (X′X)−1 X′, where the columns of X represent the largest 1/3 of the eigenvectors of the covariance matrix, is plotted. The horizontal line is a heuristic used in regression to imply high leverage points. Note that common motion correction schemes (AIR and SPM) do not measurably affect predictability. MCICA = motion corrected ICA. (b) Even after standard motion correction, ICA components indicative of movement can still be isolated.