Proc Natl Acad Sci U S A
February 1, 2022
Daniel Toker, Ioannis Pappas, Janna D. Lendner et al.
148 citations
During conscious states, the cortex operates near a mathematically specific critical point called the edge-of-chaos, the boundary between stability and chaos. Applying a modified 0-1 chaos test to ECoG and MEG recordings from humans and macaques, evidence suggests that unconscious states—such as generalized seizure and anesthesia—involve a shift of low-frequency cortical oscillations away from this critical point, disrupting information processing. Psychedelic states tune these oscillations closer to the critical point, potentially increasing information richness. Analysis of clinical EEG from patients with disorders of consciousness indicates that measuring proximity to this critical point may serve as a clinical index of consciousness.
Behavioural Brain Research
January 5, 2025
Santiago Castro-Zaballa, Joaquín González, Matías Cavelli et al.
4 citations
In cats, high-frequency oscillations (HFO, >100 Hz) in the brain's electrical activity are linked to breathing during wakefulness but not during sleep. A sub-anesthetic dose of ketamine increases the power of these HFO, and they remain tied to the inhalation phase of respiration. The enhanced HFO appear to originate in the olfactory bulb and travel to the prefrontal cortex. Blocking the nostrils reduces the ketamine-enhanced HFO in both regions. Auditory stimulation does not affect these oscillations. The findings suggest that ketamine's enhancement of respiration-coupled HFO may disrupt cortical information processing, potentially contributing to its neuropsychiatric effects.
bioRxiv
June 11, 2021
Daniel Toker, Ioannis Pappas, Janna D. Lendner et al.
3 citations
preprint
During conscious states, the cortex's electrical activity operates near the edge-of-chaos critical point—the boundary between stability and chaos. Applying a new chaos test to ECoG and MEG recordings from humans and macaques across waking, seizure, anesthesia, and psychedelic states shows that unconsciousness shifts cortical dynamics away from this critical point, disrupting information processing. Psychedelics may enhance information-richness by tuning activity closer to this point. Analysis of EEG from patients with disorders of consciousness suggests that measuring proximity to the edge-of-chaos critical point could serve as a clinical biomarker of consciousness.
Neuroimage
February 4, 2026
Gabriel A. Della Bella, Agustina Velez Picatto, Dante Sebastián Galván Rial et al.
A participant who can reliably enter a self-induced non-ordinary state of consciousness (NOC) characterized by vivid imagery, altered bodily perception, and a sense of unity underwent 20 fMRI sessions. Compared to a control group, during the transition into the NOC state, functional connectivity became more variable, indicating temporary destabilization of network organization. In the NOC state, connectivity between brain networks broadly decreased, especially visual cortex coupling with auditory, sensorimotor, and other regions, while frontoparietal and salience networks increased coupling with precuneus and temporal areas, matching reports of inward attention and absorption. Entropy and complexity measures tracked the experience and returned to baseline afterward.
bioRxiv Preprint Server
August 17, 2021
Nicolas Fuentes, Alexis García, Ramón Guevara et al.
preprint
The complexity of brain activity can serve as a correlate of consciousness. In monkeys, electrocorticogram recordings were analyzed using information quantifiers to compare stages of general anesthesia. For propofol and medetomidine, the anesthetized state showed a reduction in brain activity complexity. Conversely, ketamine produced an increase in complexity measurements, linked to increased activity in certain brain regions. Complexity of brain activity is a good indicator for evaluating different levels of consciousness awareness, in both anesthetized and non-anesthetized states.