Fig. 2.

Simulation of a five-dipole network. Five dipoles with differing carrier frequencies in the range 8–26 Hz, modulated in amplitude by a simple five-node network drawn from Smith etal. (2011), were placed into five ROIs of a 38-ROI parcellation of the cortex, and the signals recorded in a set of 306 MEG sensors were simulated with additive measurement noise. Ashows the locations of the five simulated dipoles; B a surface rendering of the 38 ROIs drawn from a laterally-split version of the Harvard–Oxford cortical atlas in FSL; C shows the network matrix used to simulate the activities in the five dipoles, placed within context of all 38 ROIs considered in later analysis; D shows the network as a graph, indicating the directions of the network edges and the Poisson processes stimulating each node independently; E shows example amplitude time-courses from a simpler two-node network, with one node (orange) driving the other (black), and both stimulated by independent Poisson processes; and F displays the modulation of the activations of two dipoles by the amplitudes in E.