Thalamic activity is a neural correlate of connected consciousness

British Journal of Anaesthesia · 2023 · 1 citations

• Neuroscience
• Psychology
• Cognitive psychology

Decreased Thalamic Activity Is a Correlate for Disconnectedness during Anesthesia with Propofol, Dexmedetomidine and Sevoflurane But Not S-Ketamine

Journal of Neuroscience · 2023 · 20 citations

• Anesthesia
• Medicine
• Psychology

doses of four commonly used anesthetics or saline placebo. We demonstrate that state-related effects are remarkably limited compared with the widespread cortical effects related to drug exposure. In particular, decreased thalamic activity was associated with disconnectedness with all used anesthetics except for S-ketamine.

Foundations of Human Consciousness: Imaging the Twilight Zone

Journal of Neuroscience · 2020 · 90 citations

• Psychology
• Neuroscience
• Anesthesia

Trying to understand the biological basis of human consciousness is currently one of the greatest challenges of neuroscience. While the loss and return of consciousness regulated by anesthetic drugs and physiological sleep are used as model systems in experimental studies on consciousness, previous research results have been confounded by drug effects, by confusing behavioral "unresponsiveness" and internally generated consciousness, and by comparing brain activity levels across states that differ in several other respects than only consciousness. Here, we present carefully designed studies that overcome many previous confounders and for the first time reveal the neural mechanisms underlying human consciousness and its disconnection from behavioral responsiveness, both during anesthesia and during normal sleep, and in the same study subjects.

Impact of Global Mean Normalization on Regional Glucose Metabolism in the Human Brain

Neural Plasticity · 2018-06-12 · 18 citations

Because the human brain consumes a disproportionate fraction of the resting body’s energy, positron emission tomography (PET) measurements of absolute glucose metabolism (CMR glc ) can serve as disease biomarkers. Global mean normalization (GMN) of PET data reveals disease-based differences from healthy individuals as fractional changes across regions relative to a global mean. To assess the impact of GMN applied to metabolic data, we compared CMR glc with and without GMN in healthy awake volunteers with eyes closed (i.e., control) against specific physiological/clinical states, including healthy/awake with eyes open, healthy/awake but congenitally blind, healthy/sedated with anesthetics, and patients with disorders of consciousness. Without GMN, global CMR glc alterations compared to control were detected in all conditions except in congenitally blind where regional CMR glc variations were detected in the visual cortex. However, GMN introduced regional and bidirectional CMR glc changes at smaller fractions of the quantitative delocalized changes. While global information was lost with GMN, the quantitative approach (i.e., a validated method for quantitative baseline metabolic activity without GMN) not only preserved global CMR glc alterations induced by opening eyes, sedation, and varying consciousness but also detected regional CMR glc variations in the congenitally blind. These results caution the use of GMN upon PET-measured CMR glc data in health and disease.

Using Positron Emission Tomography in Revealing the Mystery of General Anesthesia: Study Design Challenges and Opportunities

Methods in enzymology on CD-ROM/Methods in enzymology · 2018-01-01 · 5 citations

Faculty Opinions recommendation of Frequency-selective control of cortical and subcortical networks by central thalamus.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature · 2016-06-16

Faculty Opinions recommendation of Rapid fragmentation of neuronal networks at the onset of propofol-induced unconsciousness.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature · 2013-03-04

Evolution of consciousness: Phylogeny, ontogeny, and emergence from general anesthesia

Proceedings of the National Academy of Sciences · 2013-06-10 · 148 citations

Are animals conscious? If so, when did consciousness evolve? We address these long-standing and essential questions using a modern neuroscientific approach that draws on diverse fields such as consciousness studies, evolutionary neurobiology, animal psychology, and anesthesiology. We propose that the stepwise emergence from general anesthesia can serve as a reproducible model to study the evolution of consciousness across various species and use current data from anesthesiology to shed light on the phylogeny of consciousness. Ultimately, we conclude that the neurobiological structure of the vertebrate central nervous system is evolutionarily ancient and highly conserved across species and that the basic neurophysiologic mechanisms supporting consciousness in humans are found at the earliest points of vertebrate brain evolution. Thus, in agreement with Darwin's insight and the recent "Cambridge Declaration on Consciousness in Non-Human Animals," a review of modern scientific data suggests that the differences between species in terms of the ability to experience the world is one of degree and not kind.

Shaker-Related Potassium Channels in the Central Medial Nucleus of the Thalamus Are Important Molecular Targets for Arousal Suppression by Volatile General Anesthetics

Journal of Neuroscience · 2013-10-09 · 66 citations

The molecular targets and neural circuits that underlie general anesthesia are not fully elucidated. Here, we directly demonstrate that Kv1-family (Shaker-related) delayed rectifier K(+) channels in the central medial thalamic nucleus (CMT) are important targets for volatile anesthetics. The modulation of Kv1 channels by volatiles is network specific as microinfusion of ShK, a potent inhibitor of Kv1.1, Kv1.3, and Kv1.6 channels, into the CMT awakened sevoflurane-anesthetized rodents. In heterologous expression systems, sevoflurane, isoflurane, and desflurane at subsurgical concentrations potentiated delayed rectifier Kv1 channels at low depolarizing potentials. In mouse thalamic brain slices, sevoflurane inhibited firing frequency and delayed the onset of action potentials in CMT neurons, and ShK-186, a Kv1.3-selective inhibitor, prevented these effects. Our findings demonstrate the exquisite sensitivity of delayed rectifier Kv1 channels to modulation by volatile anesthetics and highlight an arousal suppressing role of Kv1 channels in CMT neurons during the process of anesthesia.

La evolución de la conciencia: filogenia, ontogenia y su surgimiento a partir de la anestesia general

2013-01-01

Evolution of consciousness: Phylogeny, ontogeny and emergence from general anesthesia Are animals conscious? If so, when did consciousness evolve? We address these long-standing and essential questions using a modern neuroscientific approach that draws on diverse fields such as consciousness studies, evolutionary neurobiology, animal psychology, and anesthesiology. We propose that the stepwise emergence from general anesthesia can serve as a reproducible model to study the evolution of consciousness across various species and use current data from anesthesiology to shed light on the phylogeny of consciousness. Ultimately, we conclude that the neurobiological structure of the vertebrate central nervous system is evolutionarily ancient and highly conserved across species and that the basic neurophysiologic mechanisms supporting consciousness in humans are found at the earliest points of vertebrate brain evolution. Thus, in agreement with Darwin’s insight and the recent “Cambridge Declaration on Consciousness in Non-Human Animals,” a review of modern scientific data suggests that the differences between species in terms of the ability to experience the world is one of degree and not kind.