Efficiency of Functional Brain Networks and Intellectual Performance

a, b, The results of the group averaged characteristic path length L and L^random (a) and the results of clustering coefficient C and C^random (b) for cutoff thresholds 0.05 ≤ T ≤ 0.5. L^random and C^random reflect the characteristic path length and clustering coefficient of a comparable random network. L was found to be ∼ L^random for T ≤ 0.5, and C was found to be >C^random for T ≥ 0.3 (2-sample t test, df = 36, all p < α of 0.01, Bonferroni corrected for multiple comparisons of T). c, d, Matching λ (L/L^random) and γ (C/C^random) values for all T. The functional brain networks showed a clear small-world organization, expressed by λ ≈ 1 (c) and γ ≫ 1 (d) for T ≥ 0.3 (1-sample t test, df = 18, all p < α of 0.01, Bonferroni corrected for multiple comparisons of T).