over family-wise error in the mapping analysis, GLM effects were thresholded with reference to Monte Carlo–style simulations (10,000 iterations) using the FreeSurfer program mri_surfcluster under the assumption that the statistical output was z-distributed. These simulations provided estimates of the size of map vertex clusters expected 5% of the time or less if the GLM were performed on sets of random data with the same dimensions as our observed data sets, i.e., cluster-size thresholds corresponding to alpha values of p < =0.05 for two-tailed tests.
