1
|
Luppi AI. What anaesthesia reveals about human brains and consciousness. Nat Hum Behav 2024; 8:801-804. [PMID: 38589704 DOI: 10.1038/s41562-024-01860-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Affiliation(s)
- Andrea I Luppi
- Department of Psychiatry and Centre for Eudaimonia and Human Flourishing, University of Oxford, Oxford, UK.
- Division of Anaesthesia, University of Cambridge, Cambridge, UK.
- St John's College, University of Cambridge, Cambridge, UK.
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
| |
Collapse
|
2
|
Belov D, Fesenko Z, Efimov A, Lakstygal A, Efimova E. Different sensitivity to anesthesia according to ECoG data in dopamine transporter knockout and heterozygous rats. Neurosci Lett 2022; 788:136839. [PMID: 35964824 DOI: 10.1016/j.neulet.2022.136839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/22/2022] [Accepted: 08/09/2022] [Indexed: 10/15/2022]
Abstract
Dopamine in the brain is involved in many important functions, including the regulation of wakefulness. There is also some evidence suggesting that the dopamine function is crucial in anesthetic function. The state of anesthesia is characterized by a change in the level of consciousness and a change in brain electrical activity. Due to impaired mechanisms of dopamine transportation back to the synaptic terminal, dopamine transporter (DAT) knockout and heterozygous rats have increased levels of the extracellular dopamine. In our work, we registered ECoG disturbances in knockout and heterozygous rats, as well as disturbances in tone and activity in acute experiments under the anesthesia Zoletil (tiletamine and zolazepam) from the somatosensory cortex using a NeuroNexus flat multielectrode array to study gamma activity. We also used four low-resistance electrodes to control the slow rhythm. Both low-resistance and high-resistance electrodes showed differences in the ECoG spectrum of heterozygotes and total knockouts from the wild type and from each other. Heterozygous rats for the DAT gene (HET) showed increased rapid beta and gamma activity and decreased slow delta activity, while complete knockouts (KO), on the contrary, showed increased delta activity and decreased beta and gamma activity. Thus, the ECoG spectrum of HET is shifted to the right, while that of KO is shifted to the left. Full knockouts also showed decreased spatial synchronization in the 30-100 Hz gamma range compared to the wild type (WT). It is assumed that sedation of HET and KO is shifted towards opposite directions compared to WT under the same anesthesia conditions.
Collapse
Affiliation(s)
- Dmitry Belov
- V.A. Almazov NMRC, 2 Akkuratova, St., St. Petersburg 197341, Russia.
| | - Zoia Fesenko
- Department of Biology, Saint Petersburg State University, Universitetskaya nab., 7-9, Saint Petersburg 199034, Russia; Institute of Translational Biomedicine, Saint Petersburg State University, 7-9 Universitetskaya nab., Saint Petersburg 199034, Russia
| | - Andrey Efimov
- Institute of Translational Biomedicine, Saint Petersburg State University, 7-9 Universitetskaya nab., Saint Petersburg 199034, Russia
| | - Anton Lakstygal
- Department of Biology, Saint Petersburg State University, Universitetskaya nab., 7-9, Saint Petersburg 199034, Russia
| | - Evgeniya Efimova
- Institute of Translational Biomedicine, Saint Petersburg State University, 7-9 Universitetskaya nab., Saint Petersburg 199034, Russia
| |
Collapse
|
3
|
Mesbah-Oskui L, Gurges P, Liu WY, Horner RL. Optical Stimulation of Thalamic Spindle Circuitry Sustains Electroencephalogram Patterns of General Anesthesia but not Duration of Loss of Consciousness. Neuroscience 2021; 468:110-122. [PMID: 34126184 DOI: 10.1016/j.neuroscience.2021.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 06/03/2021] [Accepted: 06/06/2021] [Indexed: 10/21/2022]
Abstract
Alterations in thalamic GABAergic signaling are implicated in mediating the rise in 12-30 Hz electroencephalogram (EEG) activity that signals anesthetic-induced loss-of-consciousness with GABAA receptor-targeting general anesthetics. A number of modeling studies have identified that anesthetic-induced alterations in thalamocortico-corticothalamic signaling in the same network that generates sleep spindles would be sufficient to elicit this key EEG signature of anesthetic hypnosis with general anesthetic agents. Accordingly, we hypothesize that targeted stimulation of this thalamic GABAergic circuitry into a sleep-spindle mode of activity would promote the general anesthetic effects of etomidate. We recorded EEG activity and loss-of-righting reflex in transgenic mice expressing channel rhodopsin-2 on GABAergic neurons (ChR2-VGAT, n = 8) and control, wild-type mice (C57BL/6J, n = 8). On two consecutive days mice were randomly assigned to receive spindle-rhythm stimulation via an optical probe targeting the left reticular thalamic nucleus or no stimulation. After an initial 30-minute recording, mice were administered etomidate (12 mg/kg, intraperitoneal) and recorded for 90 min with or without optical stimulation. Etomidate elicited an increase in 12-30 Hz EEG power in wild-type and ChR2-VGAT mice for 20 min following administration (p < 0.001). Optical spindle-rhythm stimulation prolonged the increase in 12-30 Hz activity in ChR2-VGAT mice only (p = 0.023). Spindle-rhythm stimulation also increased the incidence and duration of sleep spindle-like oscillations in ChR2-VGAT mice only (all p ≤ 0.001). Despite the maintained anesthetic-like changes in EEG activity, optical spindle-rhythm stimulation was not associated with changes in the time to and duration of the loss-of-righting reflex, a behavioral endpoint of etomidate-induced general anesthesia in rodents.
Collapse
Affiliation(s)
- Lia Mesbah-Oskui
- Department of Medicine, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Patrick Gurges
- Institute of Medical Science, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Wen-Ying Liu
- Institute of Medical Science, University of Toronto, Toronto, Ontario M5S 1A8, Canada; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Pharmacology, School of Basic Medical Science, Fudan University, Shanghai 200032, China
| | - Richard L Horner
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
| |
Collapse
|
4
|
Luppi AI, Spindler LRB, Menon DK, Stamatakis EA. The Inert Brain: Explaining Neural Inertia as Post-anaesthetic Sleep Inertia. Front Neurosci 2021; 15:643871. [PMID: 33737863 PMCID: PMC7960927 DOI: 10.3389/fnins.2021.643871] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 02/05/2021] [Indexed: 12/13/2022] Open
Abstract
"Neural inertia" is the brain's tendency to resist changes in its arousal state: it is manifested as emergence from anaesthesia occurring at lower drug doses than those required for anaesthetic induction, a phenomenon observed across very different species, from invertebrates to mammals. However, the brain is also subject to another form of inertia, familiar to most people: sleep inertia, the feeling of grogginess, confusion and impaired performance that typically follows awakening. Here, we propose a novel account of neural inertia, as the result of sleep inertia taking place after the artificial sleep induced by anaesthetics. We argue that the orexinergic and noradrenergic systems may be key mechanisms for the control of these transition states, with the orexinergic system exerting a stabilising effect through the noradrenergic system. This effect may be reflected at the macroscale in terms of altered functional anticorrelations between default mode and executive control networks of the human brain. The hypothesised link between neural inertia and sleep inertia could explain why different anaesthetic drugs induce different levels of neural inertia, and why elderly individuals and narcoleptic patients are more susceptible to neural inertia. This novel hypothesis also enables us to generate several empirically testable predictions at both the behavioural and neural levels, with potential implications for clinical practice.
Collapse
Affiliation(s)
- Andrea I. Luppi
- Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Lennart R. B. Spindler
- Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - David K. Menon
- Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Wolfson Brain Imaging Centre, University of Cambridge, Cambridge, United Kingdom
| | - Emmanuel A. Stamatakis
- Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| |
Collapse
|
5
|
Luppi AI, Spindler LRB, Menon DK, Stamatakis EA. The Inert Brain: Explaining Neural Inertia as Post-anaesthetic Sleep Inertia. Front Neurosci 2021; 15:643871. [PMID: 33737863 DOI: 10.3389/fnins.2021.64387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 02/05/2021] [Indexed: 05/20/2023] Open
Abstract
"Neural inertia" is the brain's tendency to resist changes in its arousal state: it is manifested as emergence from anaesthesia occurring at lower drug doses than those required for anaesthetic induction, a phenomenon observed across very different species, from invertebrates to mammals. However, the brain is also subject to another form of inertia, familiar to most people: sleep inertia, the feeling of grogginess, confusion and impaired performance that typically follows awakening. Here, we propose a novel account of neural inertia, as the result of sleep inertia taking place after the artificial sleep induced by anaesthetics. We argue that the orexinergic and noradrenergic systems may be key mechanisms for the control of these transition states, with the orexinergic system exerting a stabilising effect through the noradrenergic system. This effect may be reflected at the macroscale in terms of altered functional anticorrelations between default mode and executive control networks of the human brain. The hypothesised link between neural inertia and sleep inertia could explain why different anaesthetic drugs induce different levels of neural inertia, and why elderly individuals and narcoleptic patients are more susceptible to neural inertia. This novel hypothesis also enables us to generate several empirically testable predictions at both the behavioural and neural levels, with potential implications for clinical practice.
Collapse
Affiliation(s)
- Andrea I Luppi
- Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Lennart R B Spindler
- Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - David K Menon
- Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Wolfson Brain Imaging Centre, University of Cambridge, Cambridge, United Kingdom
| | - Emmanuel A Stamatakis
- Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| |
Collapse
|
6
|
Steiner AR, Flammer SA, Beausoleil NJ, Berg C, Bettschart-Wolfensberger R, Pinillos RG, Golledge HDW, Marahrens M, Meyer R, Schnitzer T, Toscano MJ, Turner PV, Weary DM, Gent TC. Humanely Ending the Life of Animals: Research Priorities to Identify Alternatives to Carbon Dioxide. Animals (Basel) 2019; 9:E911. [PMID: 31684044 PMCID: PMC6912382 DOI: 10.3390/ani9110911] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/14/2019] [Accepted: 10/25/2019] [Indexed: 02/06/2023] Open
Abstract
: The use of carbon dioxide (CO2) for stunning and killing animals is considered to compromise welfare due to air hunger, anxiety, fear, and pain. Despite decades of research, no alternatives have so far been found that provide a safe and reliable way to induce unconsciousness in groups of animals, and also cause less distress than CO2. Here, we revisit the current and historical literature to identify key research questions that may lead to the identification and implementation of more humane alternatives to induce unconsciousness in mice, rats, poultry, and pigs. In addition to the evaluation of novel methods and agents, we identify the need to standardise the terminology and behavioural assays within the field. We further reason that more accurate measurements of consciousness state are needed and serve as a central component in the assessment of suffering. Therefore, we propose a roadmap toward improving animal welfare during end-of-life procedures.
Collapse
Affiliation(s)
- Aline R Steiner
- Department of Clinical and Diagnostic Services, Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, 8057 Zurich, Switzerland.
| | - Shannon Axiak Flammer
- Department of Clinical Veterinary Medicine, Section of Anesthesia and Analgesia, Vetsuisse Faculty, University of Berne, Laenggassstrasse 124, 3012 Bern, Switzerland.
| | - Ngaio J Beausoleil
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Palmerston North 4410, New Zealand.
| | - Charlotte Berg
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Box 234, SE-53223 Skara, Sweden.
| | - Regula Bettschart-Wolfensberger
- Department of Clinical and Diagnostic Services, Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, 8057 Zurich, Switzerland.
| | - Rebeca García Pinillos
- Animal and Plant Health Agency and Department for Environment, Food and Rural Affairs, Nobel House, 17 Smith Square, London SW1P 3JR, UK.
| | - Huw D W Golledge
- Universities Federation for Animal Welfare (UFAW), The Old School, Brewhouse Hill, Wheathampstead, Hertfordshire AL4 8AN, UK.
| | - Michael Marahrens
- Institute of Animal Welfare and Animal Husbandry, Friedrich-Loeffler-Institut, Dörnbergstraße 25/27, 29223 Celle, Germany.
| | - Robert Meyer
- Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
| | - Tobias Schnitzer
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacherstrasse 124, 4070 Basel, Switzerland.
| | - Michael J Toscano
- Center for Proper Housing: Poultry and Rabbits (ZTHZ), Animal Welfare Division, VPH Institute, University of Bern, 3052 Zollikofen, Switzerland.
| | - Patricia V Turner
- Department of Pathobiology, University of Guelph, Guelph, ON, N1G 2W1, Canada and Charles River, Wilmington, MA 01887, USA.
| | - Daniel M Weary
- Animal Welfare Program, University of British Colombia, 2357 Main Mall, Vancouver, BC V6T 1Z4, Canada.
| | - Thomas C Gent
- Department of Clinical and Diagnostic Services, Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, 8057 Zurich, Switzerland.
| |
Collapse
|
7
|
Dennison P. The Human Default Consciousness and Its Disruption: Insights From an EEG Study of Buddhist Jhāna Meditation. Front Hum Neurosci 2019; 13:178. [PMID: 31249516 PMCID: PMC6582244 DOI: 10.3389/fnhum.2019.00178] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 05/16/2019] [Indexed: 01/09/2023] Open
Abstract
The “neural correlates of consciousness” (NCC) is a familiar topic in neuroscience, overlapping with research on the brain’s “default mode network.” Task-based studies of NCC by their nature recruit one part of the cortical network to study another, and are therefore both limited and compromised in what they can reveal about consciousness itself. The form of consciousness explored in such research, we term the human default consciousness (DCs), our everyday waking consciousness. In contrast, studies of anesthesia, coma, deep sleep, or some extreme pathological states such as epilepsy, reveal very different cortical activity; all of which states are essentially involuntary, and generally regarded as “unconscious.” An exception to involuntary disruption of consciousness is Buddhist jhāna meditation, whose implicit aim is to intentionally withdraw from the default consciousness, to an inward-directed state of stillness referred to as jhāna consciousness, as a basis to develop insight. The default consciousness is sensorily-based, where information about, and our experience of, the outer world is evaluated against personal and organic needs and forms the basis of our ongoing self-experience. This view conforms both to Buddhist models, and to the emerging work on active inference and minimization of free energy in determining the network balance of the human default consciousness. This paper is a preliminary report on the first detailed EEG study of jhāna meditation, with findings radically different to studies of more familiar, less focused forms of meditation. While remaining highly alert and “present” in their subjective experience, a high proportion of subjects display “spindle” activity in their EEG, superficially similar to sleep spindles of stage 2 nREM sleep, while more-experienced subjects display high voltage slow-waves reminiscent, but significantly different, to the slow waves of deeper stage 4 nREM sleep, or even high-voltage delta coma. Some others show brief posterior spike-wave bursts, again similar, but with significant differences, to absence epilepsy. Some subjects also develop the ability to consciously evoke clonic seizure-like activity at will, under full control. We suggest that the remarkable nature of these observations reflects a profound disruption of the human DCs when the personal element is progressively withdrawn.
Collapse
|
8
|
Gent TC, Detotto C, Vyssotski AL, Bettschart-Wolfensberger R. Epileptiform activity during inert gas euthanasia of mice. PLoS One 2018; 13:e0195872. [PMID: 29672545 PMCID: PMC5908136 DOI: 10.1371/journal.pone.0195872] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 03/30/2018] [Indexed: 02/04/2023] Open
Abstract
Carbon dioxide (CO2) is one of the most commonly used euthanasia agents for mice, yet it is highly aversive and nociceptive. Inert gases are a possible alternative, however there are qualitative reports of seizures resulting from exposure. Here we evaluate epileptiform activity caused by inert gases (N2, He, Ar and Xe) and CO2 in mice chronically instrumented for EEG/EMG undergoing single-gas euthanasia. We found that N2, He and Ar caused epileptiform activity in all animals, CO2 in half of animals and no epileptiform activity produced by Xe. Atmospheric O2 concentrations at epileptiform activity onset were significantly higher for CO2 than for all other gases and occurred soon after loss of motion, whereas N2 and Ar epileptiform activity occurred at cessation of neocortical activity. Helium caused the longest epileptiform activity and these commenced significantly before isoelectric EEG. We did not detect any epileptiform activity during active behaviour. Taken together, these results demonstrate that whilst epileptiform activity from inert gases and particularly Ar and N2 are more prevalent than for CO2, their occurrence at the onset of an isoelectric EEG is unlikely to impact on the welfare of the animal. Epileptiform activity from these gases should not preclude them from further investigation as euthanasia agents. The genesis of epileptiform activity from CO2 is unlikely to result from hypoxia as with the inert gases. Helium caused epileptiform activity before cessation of neocortical activity and for a longer duration and is therefore less suitable as an alternative to CO2.
Collapse
Affiliation(s)
- Thomas C. Gent
- Anaesthesiology Section, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland
- * E-mail:
| | - Carlotta Detotto
- Anaesthesiology Section, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland
| | | | | |
Collapse
|