Communications biology
August 5, 2024
Charlotte Maschke, Jordan O'Byrne, Michele Angelo Colombo et al.
50 citations
Consciousness may depend on brain activity poised at criticality—a state with complex patterns and high sensitivity to disruption. Analyzing resting-state EEG from healthy volunteers under propofol, xenon, or ketamine anesthesia, the study found that unconsciousness (from propofol or xenon) shifted brain dynamics away from avalanche criticality and the edge of chaos. Ketamine anesthesia preserved consciousness (vivid dreams) and criticality. Dynamical properties from resting EEG accurately predicted individual values of the perturbational complexity index (PCI), a TMS-based consciousness measure. The findings link perturbational complexity to criticality and suggest criticality is necessary for consciousness.
bioRxiv : the preprint server for biology
October 31, 2023
Charlotte Maschke, Jordan O'Byrne, Michele Angelo Colombo et al.
7 citations
preprint
Consciousness may depend on brain activity poised at criticality, a state with optimal computational properties. Electroencephalograms were recorded from healthy, unresponsive volunteers under propofol, xenon, or ketamine anesthesia. Ketamine spared consciousness (vivid dreams), allowing separation of unresponsiveness from unconsciousness. Unconscious states showed a departure from both the edge of activity propagation and the edge of chaos. The perturbational complexity index (PCI), a sensitive consciousness measure, was predicted from these dynamical properties with a mean absolute error below 7%. Results link PCI to criticality and support criticality's role in consciousness.
medRxiv Preprint Server
December 16, 2025
Derek Newman, Charlotte Maschke, George A. Mashour et al.
preprint
Propofol anesthesia can cause either the expected suppression of brain activity or a transient paradoxical excitation. EEG measures of signal complexity and entropy, specifically Type I and Type II complexity on the Complexity–Entropy Causal Plane (CECP), distinguish these divergent neural trajectories. The findings suggest that paradoxical excitation is reflected in both types of complexity, that the CECP separates excitation from suppression, and that baseline EEG complexity is linked to how susceptible a person is to propofol.
Annals of clinical and translational neurology
May 25, 2025
Charlotte Maschke, Loretta Norton, Catherine Duclos et al.
In patients with severe brain injury, the neurological wake-up test—a brief interruption of sedation to check responsiveness—often yields ambiguous or absent behavioral responses, limiting its prognostic value. Recording 128-channel EEG from 41 such patients during propofol sedation interruption revealed that brain responses, measured by EEG power, spatial ratios, and the spectral exponent, can show signs of waking even when behavior does not. Combining EEG with behavioral assessment improved predictions of survival, recovery of consciousness, and long-term functional outcomes, outperforming the predictions of attending physicians. EEG can complement the wake-up test to better inform clinicians, families, and treatment planning.