Cell Reports
May 27, 2025
Alexandra G Bardon, Jesus J Ballesteros, Scott L Brincat et al.
8 citations
Many anesthetics cause loss of consciousness despite having diverse underlying molecular and circuit actions. To explore the convergent effects of these drugs, we examine how anesthetic doses of ketamine and dexmedetomidine affect bilateral oscillations in the prefrontal cortex of nonhuman primates. Both anesthetics increase phase locking in the ventrolateral and dorsolateral prefrontal cortex,...
Annual Review of Neuroscience
February 19, 2025
Macauley Smith Breault, Sirma Orguc, Ohyoon Kwon et al.
13 citations
Major depressive disorder and treatment-resistant depression are significant worldwide health problems that need new therapies. The success of the anesthetic ketamine as an antidepressant is well known. It is less widely known that several other anesthetic agents have also shown antidepressant effects. These include nitrous oxide, propofol, isoflurane, sevoflurane, dexmedetomidine, and xenon....
Nature and Science of Sleep
2025
David R Schreier, Matteo Fecchio, Christian S Guay et al.
Dexmedetomidine (DEX) is a well-tolerated sedative drug that induces a sleep-like state. DEX sedation offers a model to study transitions between different states of consciousness (indicated by, eg, behavior, the electroencephalogram (EEG), or transcranial magnetic stimulation (TMS) evoked EEG responses). However, the effects of repeated DEX exposure on recovery are poorly understood and will...
Proceedings of the National Academy of Sciences of the United States of America
October 15, 2024
Yihan Sophy Xiong, Jacob Donoghue, Mikael Lundqvist et al.
32 citations
Predictive coding is a fundamental function of the cortex. The predictive routing model proposes a neurophysiological implementation for predictive coding. Predictions are fed back from the deep-layer cortex via alpha/beta (8 to 30 Hz) oscillations. They inhibit the gamma (40 to 100 Hz) and spiking that feed sensory inputs forward. Unpredicted inputs arrive in circuits unprepared by alpha/beta,...
Proceedings of the National Academy of Sciences of the United States of America
May 28, 2024
Elie Adam, Marek Kowalski, Oluwaseun Akeju et al.
30 citations
Ketamine is an N-methyl-D-aspartate (NMDA)-receptor antagonist that produces sedation, analgesia, and dissociation at low doses and profound unconsciousness with antinociception at high doses. At high and low doses, ketamine can generate gamma oscillations (>25 Hz) in the electroencephalogram (EEG). The gamma oscillations are interrupted by slow-delta oscillations (0.1 to 4 Hz) at high doses....
Science Translational Medicine
May 1, 2024
Brian L Edlow, Mark Olchanyi, Holly J Freeman et al.
39 citations
Consciousness is composed of arousal (i.e., wakefulness) and awareness. Substantial progress has been made in mapping the cortical networks that underlie awareness in the human brain, but knowledge about the subcortical networks that sustain arousal in humans is incomplete. Here, we aimed to map the connectivity of a proposed subcortical arousal network that sustains wakefulness in the human...
bioRxiv Preprint Server
July 13, 2023
Brian L Edlow, Mark Olchanyi, Holly J Freeman et al.
preprint
Consciousness is comprised of arousal (i.e., wakefulness) and awareness. Substantial progress has been made in mapping the cortical networks that modulate awareness in the human brain, but knowledge about the subcortical networks that sustain arousal is lacking. We integrated data from ex vivo diffusion MRI, immunohistochemistry, and in vivo 7 Tesla functional MRI to map the connectivity of a...
Nature Communications
March 29, 2023
Fangyun Tian, Laura D. Lewis, David W. Zhou et al.
63 citations
The neural mechanisms underpinning ketamine’s dissociative and antidepressant effects remain poorly understood. Here, the authors analyzed ketamine-induced brain dynamics with intracranial recordings in humans and found that ketamine engages different brain areas in distinct frequency-dependent patterns that may relate to its dissociative and antidepressant effects. Ketamine produces...
bioRxiv Preprint Server
May 2, 2022
Fangyun Tian, Laura D. Lewis, David W. Zhou et al.
preprint
Subanesthetic doses of ketamine produce rapid and sustained anti-depressant effects in patients with treatment-resistant depression. Unfortunately, the usefulness of ketamine as a treatment is limited by its potential for abuse because of psychotropic side effects such as dissociation. Understanding the brain dynamics and the neural circuits involved in ketamine’s effects could lend insight...
PLoS Computational Biology
August 18, 2021
Sourish Chakravarty, Indie C. Garwood, S. Chakravarty et al.
32 citations
Ketamine is an NMDA receptor antagonist commonly used to maintain general anesthesia. At anesthetic doses, ketamine causes high power gamma (25-50 Hz) oscillations alternating with slow-delta (0.1-4 Hz) oscillations. These dynamics are readily observed in local field potentials (LFPs) of non-human primates (NHPs) and electroencephalogram (EEG) recordings from human subjects. However, a detailed...
medRxiv
November 16, 2020
Indie C. Garwood, S. Chakravarty, Jacob Donoghue et al.
preprint
Abstract Ketamine is an NMDA receptor antagonist commonly used to maintain general anesthesia. At anesthetic doses, ketamine causes bursts of 30-50 Hz oscillations alternating with 0.1 to 10 Hz oscillations. These dynamics are readily observed in local field potentials (LFPs) of non-human primates (NHPs) and electroencephalogram (EEG) recordings from human subjects. However, a detailed...
Journal of Affective Disorders
2019
Dawn F. Ionescu, Kate H Bentley, M. Eikermann et al.
179 citations
BACKGROUND Several studies indicate that ketamine has rapid antidepressant effects in patients with treatment-resistant depression (TRD). The extent to which repeated doses of ketamine (versus placebo) reduce depression in the short and long term among outpatients with TRD and chronic, current suicidal ideation remains unknown. METHODS Twenty-six medicated outpatients with severe major...