The group mean maps of the 4 microstate classes are shown in Fig. 1. They closely resembled classes previously observed in eye-closed EEG [29] and were labeled accordingly. Both groups had two microstate classes (A and B) with diagonally oriented axes of the mapped field, one class (C) with a clear anterior-posterior orientation, and one (D) with a fronto-central extreme location. The four microstate classes accounted for a mean of 76.2% (S.D.: 6.9%) of the data variance across healthy controls, and of 75.7% (S.D.: 7.2%) across patients with PD. The duration, occurrence, and total time for the 4 microstate classes are shown in Fig. 2.
