Functional connectivity may be measured as long-range synchronization of the EEG, MEG, or other dynamic brain signals.[5] Synchronized brain regions may also be identified using spatial independent component analysis (ICA). The set of identified brain areas that are linked together in a large-scale network varies with cognitive function.[6] When the cognitive state is not explicit (i.e., the subject is at "rest"), the large-scale brain network is a resting state network (RSN). As a physical system with graph-like properties,[5] a large-scale brain network has both nodes and edges, and cannot be identified simply by the co-activation of brain areas.