SimMEEG software for simulating event-related MEG and EEG data with underlying functional connectivity

Simulating electromagnetic brain signals is becoming more and more prevalent because of the need to verify and validate electrophysiological analysis methods, especially with regards to measurements of functional connectivity and phase-amplitude coupling (PAC).

A Matlab software package with a graphical user interface, called SimMEEG, was developed so that novice and expert users could input basic signal parameters (e.g., multiple frequencies, amplitudes, durations, phase interactions, and phase-amplitude couplings) in order to simulate signals that approximate event-related brain activity. A major objective for developing this software was to create software to simulate interacting brain signals that could be used to verify functional connectivity analyses, specifically phase-locking value (PLV), phase-lag index (PLI) algorithms, and PAC. SimMEEG simulates three sources with various parameters defined by users. Users can define, multiple frequencies, event-related changes in amplitude, synchronizations (i.e., PLV and PLI), and PAC.

SimMEEG simulated signals that estimated the signal input parameters within specific target limits for PLV, PLI, and PAC. In addition, SimMEEG's synthetic signals closely approximated real human visual event-related responses. The Monte-Carlo module was used to simulate ten MEG and EEG datasets, conduct function connectivity analyses for comparison among several inverse solutions, and generate errors from ground truth. SimMEEG identified inverse solutions that had good and poor performances for functional connectivity analyses.

Comparison between other simulation methods and SimMEEG are discussed.

SimMEEG software could be used to simulate real human EEG and MEG to aid in verification of analysis pipelines by comparing analyzed results to the simulated ground truth of the user-defined event-related brain signals. A core program within SimMEEG, called SimSignals, might also be used in other fields that would benefit from simulations of three interacting signals.