Efficiency-cost plots (Global Efficiency (<i>E</i>) minus Network Density (<i>D</i>)) of EEG-based brain networks as a function of density values.

<p>Mean values with bars corresponding to the standard errors of the efficiency-cost curves are plotted for different frequency bands including theta (3–7 Hz), alpha (7–13 Hz), beta (13–30 Hz) and gamma (30–50 Hz).The graphs show the metrics for the functional networks obtained from EEG time series of 30 healthy subjects (black lines) and the randomized networks (cyan lines). The randomized networks have the same degree sequence as the original networks. The red asterisk above the plots represent the density value for which the two populations have significantly different median (Wilcoxon’s ranksum test; P < 0.05).