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Mashour GA, Lee U, Pal D, Li D. Consciousness and the Dying Brain. Anesthesiology 2024; 140:1221-1231. [PMID: 38603803 PMCID: PMC11096058 DOI: 10.1097/aln.0000000000004970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
The near-death experience has been reported since antiquity and is often characterized by the perception of light, interactions with other entities, and life recall. Near-death experiences can occur in a variety of situations, but they have been studied systematically after in-hospital cardiac arrest, with an incidence of 10 to 20%. Long attributed to metaphysical or supernatural causes, there have been recent advances in understanding the neurophysiologic basis of this unique category of conscious experience. This article reviews the epidemiology and neurobiology of near-death experiences, with a focus on clinical and laboratory evidence for a surge of neurophysiologic gamma oscillations and cortical connectivity after cardiac and respiratory arrest.
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Affiliation(s)
- George A. Mashour
- Department of Anesthesiology, University of Michigan Medical School; Ann Arbor, MI, USA
- Center for Consciousness Science, University of Michigan Medical School; Ann Arbor, MI, USA
- Neuroscience Graduate Program, University of Michigan Medical School; Ann Arbor, MI, USA
- Department of Pharmacology, University of Michigan Medical School; Ann Arbor, MI, USA
| | - UnCheol Lee
- Department of Anesthesiology, University of Michigan Medical School; Ann Arbor, MI, USA
- Center for Consciousness Science, University of Michigan Medical School; Ann Arbor, MI, USA
| | - Dinesh Pal
- Department of Anesthesiology, University of Michigan Medical School; Ann Arbor, MI, USA
- Center for Consciousness Science, University of Michigan Medical School; Ann Arbor, MI, USA
- Neuroscience Graduate Program, University of Michigan Medical School; Ann Arbor, MI, USA
- Department of Molecular and Integrative Physiology; University of Michigan Medical School; Ann Arbor, MI, USA
| | - Duan Li
- Department of Anesthesiology, University of Michigan Medical School; Ann Arbor, MI, USA
- Center for Consciousness Science, University of Michigan Medical School; Ann Arbor, MI, USA
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Woeppel KM, Krahe DD, Robbins EM, Vazquez AL, Cui XT. Electrically Controlled Vasodilator Delivery from PEDOT/Silica Nanoparticle Modulates Vessel Diameter in Mouse Brain. Adv Healthc Mater 2024; 13:e2301221. [PMID: 37916912 PMCID: PMC10842908 DOI: 10.1002/adhm.202301221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 10/16/2023] [Indexed: 11/03/2023]
Abstract
Vascular damage and reduced tissue perfusion are expected to majorly contribute to the loss of neurons or neural signals around implanted electrodes. However, there are limited methods of controlling the vascular dynamics in tissues surrounding these implants. This work utilizes conducting polymer poly(ethylenedioxythiophene) and sulfonated silica nanoparticle composite (PEDOT/SNP) to load and release a vasodilator, sodium nitroprusside, to controllably dilate the vasculature around carbon fiber electrodes (CFEs) implanted in the mouse cortex. The vasodilator release is triggered via electrical stimulation and the amount of release increases with increasing electrical pulses. The vascular dynamics are monitored in real-time using two-photon microscopy, with changes in vessel diameters quantified before, during, and after the release of the vasodilator into the tissues. This work observes significant increases in vessel diameters when the vasodilator is electrically triggered to release, and differential effects of the drug release on vessels of different sizes. In conclusion, the use of nanoparticle reservoirs in conducting polymer-based drug delivery platforms enables the controlled delivery of vasodilator into the implant environment, effectively altering the local vascular dynamics on demand. With further optimization, this technology could be a powerful tool to improve the neural electrode-tissue interface and study neurovascular coupling.
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Affiliation(s)
- Kevin M Woeppel
- Department of Bioengineering, University of Pittsburgh, United States
| | - Daniela D Krahe
- Department of Bioengineering, University of Pittsburgh, United States
| | - Elaine M Robbins
- Department of Bioengineering, University of Pittsburgh, United States
| | - Alberto L Vazquez
- Department of Bioengineering, University of Pittsburgh, United States
- Center for Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, United States
- Department of Radiology, University of Pittsburgh, United States
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, United States
| | - Xinyan Tracy Cui
- Department of Bioengineering, University of Pittsburgh, United States
- Center for Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, United States
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, United States
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Candia-Rivera D, Machado C. Reduced Heartbeat-Evoked Responses in a Near-Death Case Report. J Clin Neurol 2023; 19:581-588. [PMID: 37455508 PMCID: PMC10622722 DOI: 10.3988/jcn.2022.0415] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 12/30/2022] [Accepted: 01/25/2023] [Indexed: 07/18/2023] Open
Abstract
BACKGROUND AND PURPOSE Whether brain-heart communication continues under ventricular fibrillation (VF) remains to be determined. There is weak evidence of physiological changes in cortical activity under VF. Moreover, brain-heart communication has not previously been studied in this condition. We aimed to measure parallel changes in heart-rate variability (HRV), cortical activity, and brain-heart interactions in a patient who experienced VF. METHODS The EEG and EKG signals for the case report were acquired for approximately 20 h. We selected different 1-min-long segments based on the changes in the EKG waveform. We present the changes in heartbeat-evoked responses (HERs), HRV, and EEG power for each selected segment. RESULTS The overall physiological activity appeared to deteriorate as VF proceeded. Brain-heart interactions measured using HERs disappeared, with a few aberrant amplitudes appearing occasionally. The parallel changes in EEG and HRV were not pronounced, suggesting the absence of bidirectional neural control. CONCLUSIONS Our measurements of brain-heart interactions suggested that the evolving VF impairs communication between the central and autonomic nervous systems. These results may support that reduced brain-heart interactions reflect loss of consciousness and deterioration in the overall health state.
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Affiliation(s)
| | - Calixto Machado
- Department of Clinical Neurophysiology, Institute of Neurology and Neurosurgery, Havana, Cuba
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Dutta S, Iyer KK, Vanhatalo S, Breakspear M, Roberts JA. Mechanisms underlying pathological cortical bursts during metabolic depletion. Nat Commun 2023; 14:4792. [PMID: 37553358 PMCID: PMC10409751 DOI: 10.1038/s41467-023-40437-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 07/27/2023] [Indexed: 08/10/2023] Open
Abstract
Cortical activity depends upon a continuous supply of oxygen and other metabolic resources. Perinatal disruption of oxygen availability is a common clinical scenario in neonatal intensive care units, and a leading cause of lifelong disability. Pathological patterns of brain activity including burst suppression and seizures are a hallmark of the recovery period, yet the mechanisms by which these patterns arise remain poorly understood. Here, we use computational modeling of coupled metabolic-neuronal activity to explore the mechanisms by which oxygen depletion generates pathological brain activity. We find that restricting oxygen supply drives transitions from normal activity to several pathological activity patterns (isoelectric, burst suppression, and seizures), depending on the potassium supply. Trajectories through parameter space track key features of clinical electrophysiology recordings and reveal how infants with good recovery outcomes track toward normal parameter values, whereas the parameter values for infants with poor outcomes dwell around the pathological values. These findings open avenues for studying and monitoring the metabolically challenged infant brain, and deepen our understanding of the link between neuronal and metabolic activity.
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Affiliation(s)
- Shrey Dutta
- Brain Modelling Group, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.
- Faculty of Medicine, University of Queensland, Brisbane, QLD, Australia.
- School of Psychological Sciences, College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW, Australia.
| | - Kartik K Iyer
- Brain Modelling Group, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Sampsa Vanhatalo
- Pediatric Research Center, Department of Physiology, Helsinki University Hospital, University of Helsinki, Helsinki, Finland
| | - Michael Breakspear
- School of Psychological Sciences, College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW, Australia
- School of Medicine and Public Health, College of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - James A Roberts
- Brain Modelling Group, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
- Faculty of Medicine, University of Queensland, Brisbane, QLD, Australia
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Mingazov B, Vinokurova D, Zakharov A, Khazipov R. Comparative Study of Terminal Cortical Potentials Using Iridium and Ag/AgCl Electrodes. Int J Mol Sci 2023; 24:10769. [PMID: 37445945 DOI: 10.3390/ijms241310769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/19/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023] Open
Abstract
Brain ischemia induces slow voltage shifts in the cerebral cortex, including waves of spreading depolarization (SD) and negative ultraslow potentials (NUPs), which are considered as brain injury markers. However, different electrode materials and locations yield variable SD and NUP features. Here, we compared terminal cortical events during isoflurane or sevoflurane euthanasia using intracortical linear iridium electrode arrays and Ag/AgCl-based electrodes in the rat somatosensory cortex. Inhalation of anesthetics caused respiratory arrest, associated with hyperpolarization and followed by SD and NUP on both Ir and Ag electrodes. Ag-NUPs were bell shaped and waned within half an hour after death. Ir-NUPs were biphasic, with the early fast phase corresponding to Ag-NUP, and the late absent on Ag electrodes, phase of a progressive depolarizing voltage shift reaching -100 mV by two hours after death. In addition, late Ir-NUPs were more ample in the deep layers than at the cortical surface. Thus, intracortical Ag and Ir electrodes reliably assess early manifestations of terminal brain injury including hyperpolarization, SD and the early phase of NUP, while the late, giant amplitude phase of NUP, which is present only on Ir electrodes, is probably related to the sensitivity of Ir electrodes to a yet unidentified factor related to brain death.
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Affiliation(s)
- Bulat Mingazov
- Laboratory of Neurobiology, Kazan Federal University, Kazan 420008, Russia
| | - Daria Vinokurova
- Laboratory of Neurobiology, Kazan Federal University, Kazan 420008, Russia
| | - Andrei Zakharov
- Laboratory of Neurobiology, Kazan Federal University, Kazan 420008, Russia
- Department of Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan 420008, Russia
- Institut de Neurobiologie de la Méditerranée (Inserm U1249), Aix-Marseille Université, 13273 Marseille, France
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Charpier S. Between life and death: the brain twilight zones. Front Neurosci 2023; 17:1156368. [PMID: 37260843 PMCID: PMC10227869 DOI: 10.3389/fnins.2023.1156368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/24/2023] [Indexed: 06/02/2023] Open
Abstract
Clinically, and legally, death is considered a well-defined state of the organism characterized, at least, by a complete and irreversible cessation of brain activities and functions. According to this pragmatic approach, the moment of death is implicitly represented by a discrete event from which all cerebral processes abruptly cease. However, a growing body of experimental and clinical evidence has demonstrated that cardiorespiratory failure, the leading cause of death, causes complex time-dependent changes in neuronal activity that can lead to death but also be reversed with successful resuscitation. This review synthesizes our current knowledge of the succeeding alterations in brain activities that accompany the dying and resuscitation processes. The anoxia-dependent brain defects that usher in a process of potential death successively include: (1) a set of changes in electroencephalographic (EEG) and neuronal activities, (2) a cessation of brain spontaneous electrical activity (isoelectric state), (3) a loss of consciousness whose timing in relation to EEG changes remains unclear, (4) an increase in brain resistivity, caused by neuronal swelling, concomitant with the occurrence of an EEG deviation reflecting the neuronal anoxic insult (the so-called "wave of death," or "terminal spreading depolarization"), followed by, (5) a terminal isoelectric brain state leading to death. However, a timely restoration of brain oxygen supply-or cerebral blood flow-can initiate a mirrored sequence of events: a repolarization of neurons followed by a re-emergence of neuronal, synaptic, and EEG activities from the electrocerebral silence. Accordingly, a recent study has revealed a new death-related brain wave: the "wave of resuscitation," which is a marker of the collective recovery of electrical properties of neurons at the beginning of the brain's reoxygenation phase. The slow process of dying still represents a terra incognita, during which neurons and neural networks evolve in uncertain states that remain to be fully understood. As current event-based models of death have become neurophysiologically inadequate, I propose a new mixed (event-process) model of death and resuscitation. It is based on a detailed description of the different phases that succeed each other in a dying brain, which are generally described separately and without mechanistic linkage, in order to integrate them into a continuum of declining brain activity. The model incorporates cerebral twilight zones (with still unknown neuronal and synaptic processes) punctuated by two characteristic cortical waves providing real-time biomarkers of death- and resuscitation.
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Affiliation(s)
- Stéphane Charpier
- Sorbonne Université, Institut du Cerveau – Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié-Salpêtriére, Paris, France
- Sorbonne University, UPMC Université Paris, Paris, France
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Shlobin NA, Aru J, Vicente R, Zemmar A. What happens in the brain when we die? Deciphering the neurophysiology of the final moments in life. Front Aging Neurosci 2023; 15:1143848. [PMID: 37228251 PMCID: PMC10203241 DOI: 10.3389/fnagi.2023.1143848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 04/12/2023] [Indexed: 05/27/2023] Open
Abstract
When do we die and what happens in the brain when we die? The mystery around these questions has engaged mankind for centuries. Despite the challenges to obtain recordings of the dying brain, recent studies have contributed to better understand the processes occurring during the last moments of life. In this review, we summarize the literature on neurophysiological changes around the time of death. Perhaps the only subjective description of death stems from survivors of near-death experiences (NDEs). Hallmarks of NDEs include memory recall, out-of-body experiences, dreaming, and meditative states. We survey the evidence investigating neurophysiological changes of these experiences in healthy subjects and attempt to incorporate this knowledge into the existing literature investigating the dying brain to provide valuations for the neurophysiological footprint and timeline of death. We aim to identify reasons explaining the variations of data between studies investigating this field and provide suggestions to standardize research and reduce data variability.
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Affiliation(s)
- Nathan A. Shlobin
- Department of Neurosurgery, Henan Provincial People’s Hospital, Henan University School of Medicine, Zhengzhou, China
- Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Jaan Aru
- Institute of Computer Science, University of Tartu, Tartu, Estonia
| | - Raul Vicente
- Institute of Computer Science, University of Tartu, Tartu, Estonia
| | - Ajmal Zemmar
- Department of Neurosurgery, Henan Provincial People’s Hospital, Henan University School of Medicine, Zhengzhou, China
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, KY, United States
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Romand R, Ehret G. Neuro-functional modeling of near-death experiences in contexts of altered states of consciousness. Front Psychol 2023; 13:846159. [PMID: 36743633 PMCID: PMC9891231 DOI: 10.3389/fpsyg.2022.846159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 11/23/2022] [Indexed: 01/19/2023] Open
Abstract
Near-death experiences (NDEs) including out-of-body experiences (OBEs) have been fascinating phenomena of perception both for affected persons and for communities in science and medicine. Modern progress in the recording of changing brain functions during the time between clinical death and brain death opened the perspective to address and understand the generation of NDEs in brain states of altered consciousness. Changes of consciousness can experimentally be induced in well-controlled clinical or laboratory settings. Reports of the persons having experienced the changes can inform about the similarity of the experiences with those from original NDEs. Thus, we collected neuro-functional models of NDEs including OBEs with experimental backgrounds of drug consumption, epilepsy, brain stimulation, and ischemic stress, and included so far largely unappreciated data from fighter pilot tests under gravitational stress generating cephalic nervous system ischemia. Since we found a large overlap of NDE themes or topics from original NDE reports with those from neuro-functional NDE models, we can state that, collectively, the models offer scientifically appropriate causal explanations for the occurrence of NDEs. The generation of OBEs, one of the NDE themes, can be localized in the temporo-parietal junction (TPJ) of the brain, a multimodal association area. The evaluated literature suggests that NDEs may emerge as hallucination-like phenomena from a brain in altered states of consciousness (ASCs).
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Affiliation(s)
- Raymond Romand
- Faculty of Medicine, University of Strasbourg, Strasbourg, France,*Correspondence: Raymond Romand,
| | - Günter Ehret
- Institute of Neurobiology, University of Ulm, Ulm, Germany,Günter Ehret,
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Boyer M, Baudin P, Stengel C, Valero-Cabré A, Lohof AM, Charpier S, Sherrard RM, Mahon S. In vivo low-intensity magnetic pulses durably alter neocortical neuron excitability and spontaneous activity. J Physiol 2022; 600:4019-4037. [PMID: 35899578 DOI: 10.1113/jp283244] [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: 04/23/2022] [Accepted: 07/21/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Repetitive transcranial magnetic stimulation (rTMS) is a promising technique to alleviate neurological and psychiatric disorders caused by alterations in cortical activity. Our knowledge of the cellular mechanisms underlying rTMS-based therapies remains limited. We combined in vivo focal application of low-intensity rTMS (LI-rTMS) to the rat somatosensory cortex with intracellular recordings of subjacent pyramidal neurons to characterize the effects of weak magnetic fields at single cell level. Ten minutes of LI-rTMS delivered at 10 Hz reliably evoked action potentials in cortical neurons during the stimulation period, and induced durable attenuation of their intrinsic excitability, synaptic activity, and spontaneous firing. These results help us better understand the mechanisms of weak magnetic stimulation and should allow optimizing the effectiveness of stimulation protocols for clinical use. ABSTRACT Magnetic brain stimulation is a promising treatment for neurological and psychiatric disorders. However, a better understanding of its effects at the individual neuron level is essential to improve its clinical application. We combined focal low-intensity repetitive transcranial magnetic stimulation (LI-rTMS) to the rat somatosensory cortex with intracellular recordings of subjacent pyramidal neurons in vivo. Continuous 10 Hz LI-rTMS reliably evoked firing at ∼4-5 Hz during the stimulation period and induced durable attenuation of synaptic activity and spontaneous firing in cortical neurons, through membrane hyperpolarization and a reduced intrinsic excitability. However, inducing firing in individual neurons by repeated intracellular current injection did not reproduce LI-rTMS effects on neuronal properties. These data provide novel understanding of mechanisms underlying magnetic brain stimulation showing that, in addition to inducing biochemical plasticity, even weak magnetic fields can activate neurons and enduringly modulate their excitability. Abstract figure legend We examined by means of in vivo intracellular recordings in the rodent the effects of low-intensity (10 mT) repetitive transcranial magnetic stimulation (LI-rTMS) on the functional properties of primary somatosensory cortex pyramidal neurons. After a baseline period, during which cortical spontaneous activity and excitability were measured (Pre), LI-rTMS was applied at 10 Hz for 10 minutes. Despite their low intensity, magnetic pulses reliably evoked action potentials in cortical neurons. Ten minutes of LI-rTMS induced a progressive and long-lasting hyperpolarization of the neuronal membrane and a marked decrease in cell firing rate (Post). This was associated with an altered intrinsic neuronal excitability, characterized by reduced membrane input resistance and increased minimal current required to induce neuronal firing. A portion of this figure was created with biorender.com. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Manon Boyer
- IBPS-B2A, UMR 8256 Biological Adaptation and Ageing, Sorbonne Université & CNRS, Paris, 75005, France.,Paris Brain Institute-ICM, INSERM, CNRS, APHP, Pitié-Salpêtrière Hospital, team 'Network Dynamics and cellular excitability', Sorbonne Université, Paris, France, 75013
| | - Paul Baudin
- Paris Brain Institute-ICM, INSERM, CNRS, APHP, Pitié-Salpêtrière Hospital, team 'Network Dynamics and cellular excitability', Sorbonne Université, Paris, France, 75013
| | - Chloé Stengel
- Paris Brain Institute-ICM, INSERM, CNRS, Pitié-Salpêtrière Hospital, team Cerebral Dynamics, Plasticity and Rehabilitation Group, FRONTLAB team, Sorbonne Université, Paris, 75013, France
| | - Antoni Valero-Cabré
- Paris Brain Institute-ICM, INSERM, CNRS, Pitié-Salpêtrière Hospital, team Cerebral Dynamics, Plasticity and Rehabilitation Group, FRONTLAB team, Sorbonne Université, Paris, 75013, France
| | - Ann M Lohof
- IBPS-B2A, UMR 8256 Biological Adaptation and Ageing, Sorbonne Université & CNRS, Paris, 75005, France
| | - Stéphane Charpier
- Paris Brain Institute-ICM, INSERM, CNRS, APHP, Pitié-Salpêtrière Hospital, team 'Network Dynamics and cellular excitability', Sorbonne Université, Paris, France, 75013
| | - Rachel M Sherrard
- IBPS-B2A, UMR 8256 Biological Adaptation and Ageing, Sorbonne Université & CNRS, Paris, 75005, France
| | - Séverine Mahon
- Paris Brain Institute-ICM, INSERM, CNRS, APHP, Pitié-Salpêtrière Hospital, team 'Network Dynamics and cellular excitability', Sorbonne Université, Paris, France, 75013
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10
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Lee JW, Sreepada LP, Bevers MB, Li K, Scirica BM, Santana da Silva D, Henderson GV, Bay C, Lin AP. Magnetic Resonance Spectroscopy of Hypoxic-Ischemic Encephalopathy After Cardiac Arrest. Neurology 2022; 98:e1226-e1237. [PMID: 35017308 PMCID: PMC8967333 DOI: 10.1212/wnl.0000000000013297] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 12/27/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVES To correlate brain metabolites with clinical outcome using magnetic resonance spectroscopy (MRS) in patients undergoing targeted temperature management (TTM) after cardiac arrest and assess their relationships to MRI and EEG variables. METHODS A prospective cohort of 50 patients was studied. The primary outcome was coma recovery to follow commands. Comparison of MRS measures in the posterior cingulate gyrus, parietal white matter, basal ganglia, and brainstem were also made to 25 normative controls. RESULTS Fourteen of 50 patients achieved coma recovery before hospital discharge. There was a significant decrease in total N-acetylaspartate (NAA/Cr) and an increase in lactate/creatine (Lac/Cr) in patients who did not recover, with changes most prominent in the posterior cingulate gyrus. Patients who recovered had decrease in NAA/Cr as compared to controls. NAA/Cr had a strong monotonic relationship with MRI cortical apparent diffusion coefficient (ADC); Lac level exponentially increased with decreasing ADC. EEG suppression/burst suppression was strongly associated with Lac elevation. DISCUSSION NAA and Lac changes are associated with clinical/MRI/EEG changes consistent with hypoxic-ischemic encephalopathy (HIE) and are most prominent in the posterior cingulate gyrus. NAA/Cr decrease observed in patients with good outcomes suggests mild HIE in patients asymptomatic at hospital discharge. The appearance of cortical Lac represents a deterioration of aerobic energy metabolism and is associated with EEG background suppression, synaptic transmission failure, and severe, potentially irreversible HIE. CLASSIFICATION OF EVIDENCE This study provides Class IV evidence that in patients undergoing TTM after cardiac arrest, brain MRS-determined decrease in total NAA/Cr and an increase in Lac/Cr are associated with an increased risk of not recovering.
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Affiliation(s)
- Jong Woo Lee
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Lasya P Sreepada
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Matthew B Bevers
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Karen Li
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA.
| | - Benjamin M Scirica
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Danuzia Santana da Silva
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Galen V Henderson
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Camden Bay
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Alexander P Lin
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA.
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Abstract
BACKGROUND Electroencephalography (EEG) findings following cardiovascular collapse in death are uncertain. We aimed to characterize EEG changes immediately preceding and following cardiac death. METHODS We retrospectively analyzed EEGs of patients who died from cardiac arrest while undergoing standard EEG monitoring in an intensive care unit. Patients with brain death preceding cardiac death were excluded. Three events during fatal cardiovascular failure were investigated: (1) last recorded QRS complex on electrocardiogram (QRS0), (2) cessation of cerebral blood flow (CBF0) estimated as the time that blood pressure and heart rate dropped below set thresholds, and (3) electrocerebral silence on EEG (EEG0). We evaluated EEG spectral power, coherence, and permutation entropy at these time points. RESULTS Among 19 patients who died while undergoing EEG monitoring, seven (37%) had a comfort-measures-only status and 18 (95%) had a do-not-resuscitate status in place at the time of death. EEG0 occurred at the time of QRS0 in five patients and after QRS0 in two patients (cohort median - 2.0, interquartile range - 8.0 to 0.0), whereas EEG0 was seen at the time of CBF0 in six patients and following CBF0 in 11 patients (cohort median 2.0 min, interquartile range - 1.5 to 6.0). After CBF0, full-spectrum log power (p < 0.001) and coherence (p < 0.001) decreased on EEG, whereas delta (p = 0.007) and theta (p < 0.001) permutation entropy increased. CONCLUSIONS Rarely may patients have transient electrocerebral activity following the last recorded QRS (less than 5 min) and estimated cessation of cerebral blood flow. These results may have implications for discussions around cardiopulmonary resuscitation and organ donation.
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Zhou Y, Sheremet A, Kennedy JP, DiCola NM, Maciel CB, Burke SN, Maurer AP. Spectrum Degradation of Hippocampal LFP During Euthanasia. Front Syst Neurosci 2021; 15:647011. [PMID: 33967707 PMCID: PMC8102791 DOI: 10.3389/fnsys.2021.647011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 03/23/2021] [Indexed: 11/13/2022] Open
Abstract
The hippocampal local field potential (LFP) exhibits a strong correlation with behavior. During rest, the theta rhythm is not prominent, but during active behavior, there are strong rhythms in the theta, theta harmonics, and gamma ranges. With increasing running velocity, theta, theta harmonics and gamma increase in power and in cross-frequency coupling, suggesting that neural entrainment is a direct consequence of the total excitatory input. While it is common to study the parametric range between the LFP and its complementing power spectra between deep rest and epochs of high running velocity, it is also possible to explore how the spectra degrades as the energy is completely quenched from the system. Specifically, it is unknown whether the 1/f slope is preserved as synaptic activity becomes diminished, as low frequencies are generated by large pools of neurons while higher frequencies comprise the activity of more local neuronal populations. To test this hypothesis, we examined rat LFPs recorded from the hippocampus and entorhinal cortex during barbiturate overdose euthanasia. Within the hippocampus, the initial stage entailed a quasi-stationary LFP state with a power-law feature in the power spectral density. In the second stage, there was a successive erosion of power from high- to low-frequencies in the second stage that continued until the only dominant remaining power was <20 Hz. This stage was followed by a rapid collapse of power spectrum toward the absolute electrothermal noise background. As the collapse of activity occurred later in hippocampus compared with medial entorhinal cortex, it suggests that the ability of a neural network to maintain the 1/f slope with decreasing energy is a function of general connectivity. Broadly, these data support the energy cascade theory where there is a cascade of energy from large cortical populations into smaller loops, such as those that supports the higher frequency gamma rhythm. As energy is pulled from the system, neural entrainment at gamma frequency (and higher) decline first. The larger loops, comprising a larger population, are fault-tolerant to a point capable of maintaining their activity before a final collapse.
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Affiliation(s)
- Yuchen Zhou
- Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, United States
| | - Alex Sheremet
- Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, United States.,Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Jack P Kennedy
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Nicholas M DiCola
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Carolina B Maciel
- Division of Neurocritical Care, Department of Neurology, University of Florida, Gainesville, FL, United States
| | - Sara N Burke
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| | - Andrew P Maurer
- Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, United States.,Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL, United States.,Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
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Carton-Leclercq A, Lecas S, Chavez M, Charpier S, Mahon S. Neuronal excitability and sensory responsiveness in the thalamo-cortical network in a novel rat model of isoelectric brain state. J Physiol 2020; 599:609-629. [PMID: 33095909 DOI: 10.1113/jp280266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 10/21/2020] [Indexed: 01/04/2023] Open
Abstract
KEY POINTS The neuronal and network properties that persist during an isoelectric coma remain largely unknown. We developed a new in vivo rat model to assess cell excitability and sensory responsiveness in the thalamo-cortical pathway during an isoflurane-induced isoelectric brain state. The isoelectric electrocorticogram reflected a complete interruption of spontaneous synaptic and firing activities in cortical and thalamic neurons. Cell excitability and sensory responses in the thalamo-cortical network persisted at a reduced level in the isoelectric condition and returned to control values after resumption of background brain activity. These findings could lead to a reassessment of the functional status of the drug-induced isoelectric state: a latent state in which individual neurons and networks retain to some extent the ability of being activated by external inputs. ABSTRACT The neuronal and network properties that persist in an isoelectric brain completely deprived of spontaneous electrical activity remain largely unexplored. Here, we developed a new in vivo rat model to examine cell excitability and sensory responsiveness in somatosensory thalamo-cortical networks during the interruption of endogenous brain activity induced by high doses of isoflurane. Electrocorticograms (ECoGs) from the barrel cortex were captured simultaneously with either intracellular recordings of subjacent cortical pyramidal neurons or extracellular records of the related thalamo-cortical neurons. Isoelectric ECoG periods reflected the disappearance of spontaneous synaptic and firing activities in cortical and thalamic neurons. This was associated with a sustained membrane hyperpolarization and a reduced intrinsic excitability in deep-layer cortical neurons, without significant changes in their membrane input resistance. Concomitantly, we found that whisker-evoked potentials in the ECoG and synaptic responses in cortical neurons were attenuated in amplitude and increased in latency. Impaired responsiveness in the barrel cortex paralleled with a lowering of the sensory-induced firing in thalamic cells. The return of endogenous brain electrical activities, after reinstatement of a control isoflurane concentration, led to the recovery of cortical neurons excitability and sensory responsiveness. These findings demonstrate the persistence of a certain level of cell excitability and sensory integration in the isoelectric state and the full recovery of cortico-thalamic functions after restoration of internal cerebral activities.
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Affiliation(s)
- Antoine Carton-Leclercq
- Institut du Cerveau, ICM, INSERM UMRS 1127, CNRS UMR 7225, Pitié-Salpêtrière Hospital, Paris, France
| | - Sarah Lecas
- Institut du Cerveau, ICM, INSERM UMRS 1127, CNRS UMR 7225, Pitié-Salpêtrière Hospital, Paris, France.,Sorbonne University, UPMC Université Paris, Paris, France
| | - Mario Chavez
- Institut du Cerveau, ICM, INSERM UMRS 1127, CNRS UMR 7225, Pitié-Salpêtrière Hospital, Paris, France
| | - Stéphane Charpier
- Institut du Cerveau, ICM, INSERM UMRS 1127, CNRS UMR 7225, Pitié-Salpêtrière Hospital, Paris, France.,Sorbonne University, UPMC Université Paris, Paris, France
| | - Séverine Mahon
- Institut du Cerveau, ICM, INSERM UMRS 1127, CNRS UMR 7225, Pitié-Salpêtrière Hospital, Paris, France
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