Characterizing consciousness states: EEG microstate dynamics in patients with disorders of consciousness during...

Consciousness assessment in disorders of consciousness (DoC) patients remains clinically challenging. Dynamic brain activities responsive to sensory stimulations have been suggested to contain consciousness-related information. However, primary sensory processing can occur unconsciously, necessitating evaluation of residual higher-order cognitive functions for effective assessment. In this study, we introduced a movie-viewing paradigm incorporating a scrambled version to control for primary sensory processing and applied electroencephalography (EEG) microstate analysis to capture higher-order neural dynamics. By comparing 23 DoC patients with 23 healthy individuals and 12 conscious brain-injured patients, we found significant abnormalities in microstate D in DoC patients. Healthy individuals and conscious brain-injured patients showed enhanced D-related parameters during intact movie-viewing compared to the scrambled condition. Conversely, DoC patients displayed a significant decrease in Duration, Coverage, Occurrence, and Transition Probabilities of microstate D during intact movie-viewing. Additionally, K-nearest neighbors classifier showed that the differences in microstate features between the intact and scrambled movie-viewing yielded the best classification outcome (AUC = 0.83), in which microstate D parameters serve as the most important features. Our results suggested that EEG microstates during naturalistic movie-viewing, especially microstate D, have the potential to serve as a novel, objective indicator for characterizing and diagnosing the state of consciousness.