To determine the between-group difference of the extent to which the brain is synchronized at rest, SL values of each participant were averaged across a pair of nodes and the permutation test (Fisher, 1935) was performed as in previous network studies (van den Heuvel et al., 2010; Wang et al., 2010). Briefly, the permutation test is a statistical test for the difference between two means in which the null distribution of test statistic is obtained by a number of random rearrangements (i.e. permutations) for each participant's group. First, a t-value was calculated for the averaged SL as an observed test statistic between two groups. Then, each participant was randomly reassigned to either patient or control group, resulting in the same number of participants for each group (i.e. BD:NC = 57:87 after permutation). The t-values were recalculated for the permutated groups 10,000 times, and the null distribution of test statistics was obtained for the group difference. Finally, the proportion of sampled permutations where the t-values were greater than the observed test statistic was calculated as the p-value of the observed group
