Electrocorticographic activation patterns during electroencephalographic microstates

Abstract Introduction: Electroencephalography (EEG) microstates are successive short time periods of stable scalp field potentials that represent spontaneous activation of brain resting-state networks. EEG microstates are assumed to mediate local activity patterns. To assess this hypothesis, we correlated momentary EEG microstate dynamics with the temporo-spectral evolution of electrocorticography (ECoG) and stereotactic EEG(SEEG) depth electrode recordings. Methods We analyzed resting-state data (5 min) from two participants with simultaneous noninvasive scalp EEG and invasive ECoG, and SEEG recordings. Data were recorded during the presurgical evaluation of pharmacoresistant epilepsusing subdural and intracranial electrodes. After standard preprocessing, we fitted microstate template maps to the scalp EEG data. Using covariance mapping with EEG microstate timelines and ECoG/SEEG temporo-spectral evolutions as input, we identified systematic changes in the activation of ECoG/SEEG local field potentials in different frequency bands (theta, alpha, beta, and high gamma) depending on the presence of a particular microstate class. Results We found a significant covariation of ECoG/SEEG spectral amplitudes with microstate timelines in all four frequency bands (p = .001, permutation test). The covariance patterns of the ECoG/SEEG electrodes during different microstates were similar for the two observed participants. Discussion To our knowledge, this is the first study to demonstrate distinct activation/deactivation patterns of frequency-domain ECoG local field potentials associated with simultaneously present EEG microstates.