It is important to emphasize that our results reflect genuine physiological connectivity since, unlike previously published methods, eLORETA algorithm is based on a proper model for the two components of a connection: instantaneous and lagged. In our experience, the connectivity patterns of both the classic phase synchronization and classic coherence (which include the instantaneous artifact) are dominated simply by the locations of activity maxima, which are seen as common instantaneous sources, and therefore are not related to true physiological connections [30], [31]. Compared to the imaginary part of the coherence proposed by Nolte et al. [27] as a conservative index of connectivity, the lagged connectivity measure has the important property of being relatively robust to the strength of the instantaneous component, i.e. it can still detect physiological “non-zero” lagged connectivity even in the presence of large instantaneous artifacts, while the imaginary part of the coherence fails to detect a lagged connection by tending to zero if the instantaneous component is large [30].This would also apply to phase synchronization, since it is nothing more than the coherence for unit modulus (amplitude
