Besides the above reviewed methods, there is a wide family of connectivity methods which could be used to assess functional or effective couplings between neuronal oscillations, both at the same or at different frequencies. These include, but are not limited to: phase-amplitude coupling methods, which assess the coupling between the phase of a low-frequency oscillation and the amplitude of a high-frequency oscillation (Canolty et al., 2006; Cohen, 2008; Tort et al., 2010; Özkurt and Schnitzler, 2011); amplitude-amplitude coupling methods, which investigate the covariation of aperiodic fluctuations such as the amplitudes of brain oscillations at a specific frequency (Brookes et al., 2011b; Hipp et al., 2012); model-based approaches, such as the dynamic causal models (Friston et al., 2003), which infer the causal structure of brain connections by relying on Bayesian inference; methods to assess the directionality of interactions based on the concept of Granger causality (Geweke, 1982; Kaminski and Blinowska, 1991; Sameshima and Baccalá, 1999; Marinazzo et al., 2008). In addition, methods to identify brain states can provide further insight into brain networks and especially into their dynamics. In this framework,
