EEG microstate dynamics indicate a U-shaped path to propofol-induced loss of consciousness
Fiorenzo Artoni, Julien Maillard, Juliane Britz et al. preprint
The stream of consciousness is thought to be composed of discrete brain states, reflected in EEG microstates—transient, stable patterns of global neuronal activity lasting fractions of seconds. In 23 surgical patients, high-density EEG was recorded continuously from wakefulness to unconsciousness induced by step-wise increasing propofol concentrations. Under surgical anesthesia, microstate sequences became sparser, longer-lasting, and less complex. However, moderate sedation initially increased the temporal dynamics and complexity of microstates, producing a distinctive U-shaped pattern that may correspond to paradoxical excitation. These findings suggest that normal consciousness relies on a metastable balance between order and chaos, enabling flexible state transitions, and that altered consciousness reflects changes in this balance.