NeuroImage
May 1, 2020
Matthew I Banks, Bryan M Krause, Christopher M Endemann et al.
78 citations
Disruption of cortical connectivity likely contributes to loss of consciousness during sleep and general anesthesia, but the degree of overlap in mechanisms is unclear. Using intracranial recordings from five adult neurosurgical patients, alpha-band connectivity (measured by weighted phase lag index) was compared across natural sleep stages and propofol anesthesia. In wake states, alpha-band connectivity within the temporal lobe was dominant, a pattern largely unchanged in light sleep (N1, REM) and sedated states. Transitions into states of reduced consciousness (deep sleep N2/N3 and anesthesia-induced unresponsiveness) showed dramatic shifts, with dominant connections moving to prefrontal cortex. The findings suggest common mechanisms of loss of consciousness in sleep and anesthesia.
Translational psychiatry
September 12, 2024
Christopher R Nicholas, Matthew I Banks, Richard C Lennertz et al.
10 citations
Psilocybin, a serotonergic psychedelic, can relieve symptoms in several psychiatric disorders and improve well-being, but it was unclear whether these benefits arise during the acute experience or depend on later memory of it. In 8 healthy participants, psilocybin (25 mg) was co-administered with the amnestic benzodiazepine midazolam at a dose that allowed a conscious psychedelic experience while partially impairing memory for it. Higher midazolam doses and greater memory impairment tended to associate with lower salience, insight, and well-being from psilocybin. These results suggest memory plays a role in therapeutically relevant behavioral effects of psilocybin.
Psychedelic medicine (New Rochelle, N.Y.)
September 1, 2024
Zarmeen Zahid, Ziyad W Sultan, Bryan M Krause et al.
5 citations
In mice, the serotonergic psychedelic DOI, but not ketamine, enhanced neural plasticity and metaplasticity in the hippocampus 24 hours after a single dose. Brain slices from DOI-treated animals showed stronger synaptic responses and short-term potentiation compared to saline-treated controls, with evidence that these effects involve a presynaptic mechanism. Ketamine did not produce similar changes. These findings suggest that the therapeutic benefits of serotonergic psychedelics may be supported by a window of heightened neural plasticity, whereas ketamine's effects may rely on different mechanisms.
AJNR. American journal of neuroradiology
June 3, 2025
Paloma C Frautschi, Ajay P Singh, Nicholas A Stowe et al.
2 citations
Psilocybin treatment in male mice led to structural connectivity differences in the frontal association cortex after 72 hours and microstructural changes in the primary visual cortex after 24 hours, as well as in the striatum and hippocampus after 72 hours, including increased mean diffusivity and decreased neurite density. These findings suggest that diffusion microstructure imaging can detect and characterize brain changes induced by psilocybin, offering a potential method to monitor treatment response and identify clinical endpoints for patients with major depressive disorder.
Translational psychiatry
February 14, 2026
Michael H Sutherland, Christopher R Nicholas, Richard C Lennertz et al.
Psilocybin, a serotonergic psychedelic, induces neural plasticity and alters consciousness, while midazolam, a benzodiazepine, blunts plasticity and induces sedation. In an open-label pilot study, 25 mg of oral psilocybin was given alongside intravenous midazolam at doses that allowed a full psychedelic experience but blunted memory. Electroencephalography (EEG) data showed that 15–30 minutes after dosing, when midazolam was at its target concentration, beta power increased and spectral exponent decreased. As psilocybin's effects emerged over the next six hours, Lempel-Ziv complexity and spectral exponent increased, while broadband power decreased, especially in delta, theta, and alpha bands. The findings suggest psilocybin's effects persist with midazolam, supporting its use in mechanistic studies.
British journal of anaesthesia
February 1, 2024
Cameron P Casey, Sean Tanabe, Zahra Z Farahbakhsh et al.
Many EEG-based measures previously thought to indicate unconsciousness actually track sensory connectedness—awareness of the environment—rather than consciousness itself. Analyzing data from the UNderstanding Consciousness Connectedness and Intra-Operative Unresponsiveness Study, researchers tested 10 resting-state EEG markers derived from unresponsive subjects during dexmedetomidine and propofol sedation and natural sleep. While several markers correlated with reported subjective experience (consciousness), none were specific to consciousness alone; each was also linked to connectedness. Loss of normalized-symbolic transfer entropy (front to back) was associated with connectedness across all conditions, and the shift from disconnected consciousness to unconsciousness involved significant decreases in permutation entropy and spectral exponent. The findings caution against equating unresponsiveness with unconsciousness.
Cerebral cortex (New York, N.Y. : 1991)
August 23, 2023
Bryan M Krause, Declan I Campbell, Christopher K Kovach et al.
Theories of consciousness propose that brain mechanisms for losing and regaining consciousness are similar regardless of cause. Using intracranial electroencephalography in neurosurgical patients during propofol anesthesia and overnight sleep, researchers found strikingly similar reorganization of cortical networks. Effective dimensionality of functional connectivity decreased during reduced consciousness (anesthesia unresponsiveness, N2 and N3 sleep), indicating lower network complexity. These changes were global, not region-specific. Brain regions became more functionally distant yet individual recording sites closer to nearest neighbors, reflecting decreased differentiation and integration. This network reorganization constitutes a common neural signature of reduced consciousness across anesthesia and sleep, providing a framework for understanding neural correlates of consciousness.