Fig. 2

Schematic flowchart of the EEG microstate analysis. Each EEG datum is used to calculate the GFP curve at each data point. The electric potentials of all electrodes at moments of local maxima of the GFP curve are plotted to generate topographic original maps. The original maps are submitted to a clustering algorithm, which groups the submitted maps into a small set of clusters (here: 3) based on topographic similarity, and optimal number of cluster microstate maps is generated for each subject. Finally, the cluster maps are back-fitted to the GFP curve and each data point is labeled with the cluster map that they best correlated to. Therefore, the multichannel EEG recording is now described as a series of alternating microstates