Before revision:  We introduce a system theoretic formalism of MEEG connectivity alongside its Bayesian inference: Hidden Hermitian Gaussian Graphical Model (H-HGGM). This is a source (state) GGM hidden by the MEEG observation equation , i. e. equivalent to a frequency domain Linear State Space Model (LSSM) . It is unhidden due to the Type II Likelihood approximated representation: Expected Log-Likelihood (ELL).
After revision:  We introduce a new formalism that attains for it, Hidden Gaussian Graphical State-Model (HIGGS). A neural Gaussian Graphical Model (GGM) hidden by the MEEG observation equation , i. e. equivalent to a frequency domain Linear State Space Model (LSSM) . It is unhidden due to the Type II Likelihood approximated representation: Expected Log-Likelihood (ELL).