1
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Martinez JD, Wilson LG, Brancaleone WP, Peterson KG, Popke DS, Garzon VC, Perez Tremble RE, Donnelly MJ, Mendez Ortega SL, Torres D, Shaver JJ, Jiang S, Yang Z, Aton SJ. Hypnotic treatment improves sleep architecture and EEG disruptions and rescues memory deficits in a mouse model of fragile X syndrome. Cell Rep 2024; 43:114266. [PMID: 38787724 DOI: 10.1016/j.celrep.2024.114266] [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: 07/07/2023] [Revised: 12/20/2023] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
Fragile X syndrome (FXS) is associated with disrupted cognition and sleep abnormalities. Sleep loss negatively impacts cognitive function, and one untested possibility is that disrupted cognition in FXS is exacerbated by abnormal sleep. We tested whether ML297, a hypnotic acting on G-protein-activated inward-rectifying potassium (GIRK) channels, could reverse sleep phenotypes and disrupted memory in Fmr1-/y mice. Fmr1-/y mice exhibit reduced non-rapid eye movement (NREM) sleep and fragmented NREM architecture, altered sleep electroencephalogram (EEG) oscillations, and reduced EEG coherence between cortical areas; these are partially reversed following ML297 administration. Treatment following contextual fear or spatial learning restores disrupted memory consolidation in Fmr1-/y mice. During memory recall, Fmr1-/y mice show an altered balance of activity among hippocampal principal neurons vs. parvalbumin-expressing interneurons; this is partially reversed by ML297. Because sleep disruption could impact neurophysiological phenotypes in FXS, augmenting sleep may improve disrupted cognition in this disorder.
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Affiliation(s)
- Jessy D Martinez
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lydia G Wilson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - William P Brancaleone
- Undergraduate Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kathryn G Peterson
- Undergraduate Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA
| | - Donald S Popke
- Undergraduate Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA
| | - Valentina Caicedo Garzon
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Roxanne E Perez Tremble
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Marcus J Donnelly
- Undergraduate Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Daniel Torres
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - James J Shaver
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sha Jiang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Zhongying Yang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sara J Aton
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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2
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Varma A, Udupa S, Sengupta M, Ghosh PK, Thirumalai V. A machine-learning tool to identify bistable states from calcium imaging data. J Physiol 2024; 602:1243-1271. [PMID: 38482722 DOI: 10.1113/jp284373] [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: 01/13/2023] [Accepted: 02/09/2024] [Indexed: 04/04/2024] Open
Abstract
Mapping neuronal activation using calcium imaging in vivo during behavioural tasks has advanced our understanding of nervous system function. In almost all of these studies, calcium imaging is used to infer spike probabilities because action potentials activate voltage-gated calcium channels and increase intracellular calcium levels. However, neurons not only fire action potentials, but also convey information via intrinsic dynamics such as by generating bistable membrane potential states. Although a number of tools for spike inference have been developed and are currently being used, no tool exists for converting calcium imaging signals to maps of cellular state in bistable neurons. Purkinje neurons in the larval zebrafish cerebellum exhibit membrane potential bistability, firing either tonically or in bursts. Several studies have implicated the role of a population code in cerebellar function, with bistability adding an extra layer of complexity to this code. In the present study, we develop a tool, CaMLSort, which uses convolutional recurrent neural networks to classify calcium imaging traces as arising from either tonic or bursting cells. We validate this classifier using a number of different methods and find that it performs well on simulated event rasters as well as real biological data that it had not previously seen. Moreover, we find that CaMLsort generalizes to other bistable neurons, such as dopaminergic neurons in the ventral tegmental area of mice. Thus, this tool offers a new way of analysing calcium imaging data from bistable neurons to understand how they participate in network computation and natural behaviours. KEY POINTS: Calcium imaging, compriising the gold standard of inferring neuronal activity, does not report cellular state in neurons that are bistable, such as Purkinje neurons in the cerebellum of larval zebrafish. We model the relationship between Purkinje neuron electrical activity and its corresponding calcium signal to compile a dataset of state-labelled simulated calcium signals. We apply machine-learning methods to this dataset to develop a tool that can classify the state of a Purkinje neuron using only its calcium signal, which works well on real data even though it was trained only on simulated data. CaMLsort (Calcium imaging and Machine Learning based tool to sort intracellular state) also generalizes well to bistable neurons in a different brain region (ventral tegmental area) in a different model organism (mouse). This tool can facilitate our understanding of how these neurons carry out their functions in a circuit.
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Affiliation(s)
- Aalok Varma
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Sathvik Udupa
- Department of Electrical Engineering, Indian Institute of Science, Bangalore, India
| | - Mohini Sengupta
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Prasanta Kumar Ghosh
- Department of Electrical Engineering, Indian Institute of Science, Bangalore, India
| | - Vatsala Thirumalai
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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3
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Csillag V, Bizzozzero MH, Noble JC, Reinius B, Fuzik J. Voltage-Seq: all-optical postsynaptic connectome-guided single-cell transcriptomics. Nat Methods 2023; 20:1409-1416. [PMID: 37474808 PMCID: PMC10482676 DOI: 10.1038/s41592-023-01965-1] [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: 12/14/2022] [Accepted: 06/21/2023] [Indexed: 07/22/2023]
Abstract
Understanding the routing of neuronal information requires the functional characterization of connections. Neuronal projections recruit large postsynaptic ensembles with distinct postsynaptic response types (PRTs). PRT is typically probed by low-throughput whole-cell electrophysiology and is not a selection criterion for single-cell RNA-sequencing (scRNA-seq). To overcome these limitations and target neurons based on specific PRTs for soma harvesting and subsequent scRNA-seq, we created Voltage-Seq. We established all-optical voltage imaging and recorded the PRT of 8,347 neurons in the mouse periaqueductal gray (PAG) evoked by the optogenetic activation of ventromedial hypothalamic (VMH) terminals. PRTs were classified and spatially resolved in the entire VMH-PAG connectome. We built an onsite analysis tool named VoltView to navigate soma harvesting towards target PRTs guided by a classifier that used the VMH-PAG connectome database as a reference. We demonstrated Voltage-seq by locating VMH-driven γ-aminobutyric acid-ergic neurons in the PAG, guided solely by the onsite classification in VoltView.
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Affiliation(s)
- Veronika Csillag
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
| | | | - J C Noble
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Björn Reinius
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - János Fuzik
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.
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4
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Lindquist BE, Timbie C, Voskobiynyk Y, Paz JT. Thalamocortical circuits in generalized epilepsy: Pathophysiologic mechanisms and therapeutic targets. Neurobiol Dis 2023; 181:106094. [PMID: 36990364 PMCID: PMC10192143 DOI: 10.1016/j.nbd.2023.106094] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/02/2023] [Accepted: 03/19/2023] [Indexed: 03/29/2023] Open
Abstract
Generalized epilepsy affects 24 million people globally; at least 25% of cases remain medically refractory. The thalamus, with widespread connections throughout the brain, plays a critical role in generalized epilepsy. The intrinsic properties of thalamic neurons and the synaptic connections between populations of neurons in the nucleus reticularis thalami and thalamocortical relay nuclei help generate different firing patterns that influence brain states. In particular, transitions from tonic firing to highly synchronized burst firing mode in thalamic neurons can cause seizures that rapidly generalize and cause altered awareness and unconsciousness. Here, we review the most recent advances in our understanding of how thalamic activity is regulated and discuss the gaps in our understanding of the mechanisms of generalized epilepsy syndromes. Elucidating the role of the thalamus in generalized epilepsy syndromes may lead to new opportunities to better treat pharmaco-resistant generalized epilepsy by thalamic modulation and dietary therapy.
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Affiliation(s)
- Britta E Lindquist
- UCSF Department of Neurology, Division of Neurocritical Care, United States of America; UCSF Department of Neurology, Division of Pediatric Epilepsy, United States of America; UCSF Department of Neurology, United States of America
| | - Clare Timbie
- Gladstone Institute of Neurological Disease, United States of America; UCSF Department of Neurology, Division of Pediatric Epilepsy, United States of America; UCSF Department of Neurology, United States of America
| | - Yuliya Voskobiynyk
- Gladstone Institute of Neurological Disease, United States of America; UCSF Department of Neurology, United States of America
| | - Jeanne T Paz
- Gladstone Institute of Neurological Disease, United States of America; UCSF Department of Neurology, United States of America; Kavli Institute for Fundamental Neuroscience, UCSF, United States of America.
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5
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Chamberland S, Nebet ER, Valero M, Hanani M, Egger R, Larsen SB, Eyring KW, Buzsáki G, Tsien RW. Brief synaptic inhibition persistently interrupts firing of fast-spiking interneurons. Neuron 2023; 111:1264-1281.e5. [PMID: 36787751 PMCID: PMC10121938 DOI: 10.1016/j.neuron.2023.01.017] [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: 12/28/2020] [Revised: 06/06/2022] [Accepted: 01/18/2023] [Indexed: 02/16/2023]
Abstract
Neurons perform input-output operations that integrate synaptic inputs with intrinsic electrical properties; these operations are generally constrained by the brevity of synaptic events. Here, we report that sustained firing of CA1 hippocampal fast-spiking parvalbumin-expressing interneurons (PV-INs) can be persistently interrupted for several hundred milliseconds following brief GABAAR-mediated inhibition in vitro and in vivo. A single presynaptic neuron could interrupt PV-IN firing, occasionally with a single action potential (AP), and reliably with AP bursts. Experiments and computational modeling reveal that the persistent interruption of firing maintains neurons in a depolarized, quiescent state through a cell-autonomous mechanism. Interrupted PV-INs are strikingly responsive to Schaffer collateral inputs. The persistent interruption of firing provides a disinhibitory circuit mechanism favoring spike generation in CA1 pyramidal cells. Overall, our results demonstrate that neuronal silencing can far outlast brief synaptic inhibition owing to the well-tuned interplay between neurotransmitter release and postsynaptic membrane dynamics, a phenomenon impacting microcircuit function.
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Affiliation(s)
- Simon Chamberland
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA.
| | - Erica R Nebet
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Manuel Valero
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Monica Hanani
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Robert Egger
- NYU Neuroscience Institute and Department of Otolaryngology, NYU Langone Medical Center, New York, NY 10016, USA; Center for Neural Science, New York University, New York, NY 10003, USA
| | - Samantha B Larsen
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Katherine W Eyring
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - György Buzsáki
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA; Center for Neural Science, New York University, New York, NY 10003, USA; Department of Neurology, Langone Medical Center, New York University, New York, NY, USA
| | - Richard W Tsien
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA; Center for Neural Science, New York University, New York, NY 10003, USA.
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6
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Kullmann R, Knoll G, Bernardi D, Lindner B. Critical current for giant Fano factor in neural models with bistable firing dynamics and implications for signal transmission. Phys Rev E 2022; 105:014416. [PMID: 35193262 DOI: 10.1103/physreve.105.014416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 01/05/2022] [Indexed: 06/14/2023]
Abstract
Bistability in the firing rate is a prominent feature in different types of neurons as well as in neural networks. We show that for a constant input below a critical value, such bistability can lead to a giant spike-count diffusion. We study the transmission of a periodic signal and demonstrate that close to the critical bias current, the signal-to-noise ratio suffers a sharp increase, an effect that can be traced back to the giant diffusion and large Fano factor.
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Affiliation(s)
- Richard Kullmann
- Bernstein Center for Computational Neuroscience Berlin, Philippstrasse 13, Haus 2, 10115 Berlin, Germany
- Physics Department of Humboldt University Berlin, Newtonstrasse 15, 12489 Berlin, Germany
| | - Gregory Knoll
- Bernstein Center for Computational Neuroscience Berlin, Philippstrasse 13, Haus 2, 10115 Berlin, Germany
- Physics Department of Humboldt University Berlin, Newtonstrasse 15, 12489 Berlin, Germany
| | - Davide Bernardi
- Center for Translational Neurophysiology of Speech and Communication, Fondazione Istituto Italiano di Tecnologia, via Fossato di Mortara 19, 44121 Ferrara, Italy
| | - Benjamin Lindner
- Bernstein Center for Computational Neuroscience Berlin, Philippstrasse 13, Haus 2, 10115 Berlin, Germany
- Physics Department of Humboldt University Berlin, Newtonstrasse 15, 12489 Berlin, Germany
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7
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Huang Z, Tarnal V, Vlisides PE, Janke EL, McKinney AM, Picton P, Mashour GA, Hudetz AG. Asymmetric neural dynamics characterize loss and recovery of consciousness. Neuroimage 2021; 236:118042. [PMID: 33848623 PMCID: PMC8310457 DOI: 10.1016/j.neuroimage.2021.118042] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/01/2021] [Accepted: 04/04/2021] [Indexed: 02/07/2023] Open
Abstract
Anesthetics are known to disrupt neural interactions in cortical and subcortical brain circuits. While the effect of anesthetic drugs on consciousness is reversible, the neural mechanism mediating induction and recovery may be different. Insight into these distinct mechanisms can be gained from a systematic comparison of neural dynamics during slow induction of and emergence from anesthesia. To this end, we used functional magnetic resonance imaging (fMRI) data obtained in healthy volunteers before, during, and after the administration of propofol at incrementally adjusted target concentrations. We analyzed functional connectivity of corticocortical and subcorticocortical networks and the temporal autocorrelation of fMRI signal as an index of neural processing timescales. We found that en route to unconsciousness, temporal autocorrelation across the entire brain gradually increased, whereas functional connectivity gradually decreased. In contrast, regaining consciousness was associated with an abrupt restoration of cortical but not subcortical temporal autocorrelation and an abrupt boost of subcorticocortical functional connectivity. Pharmacokinetic effects could not account for the difference in neural dynamics between induction and emergence. We conclude that the induction and recovery phases of anesthesia follow asymmetric neural dynamics. A rapid increase in the speed of cortical neural processing and subcorticocortical neural interactions may be a mechanism that reboots consciousness.
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Affiliation(s)
- Zirui Huang
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Corresponding authors. (Z. Huang), (A.G. Hudetz)
| | - Vijay Tarnal
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Phillip E. Vlisides
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Ellen L. Janke
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Amy M. McKinney
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Paul Picton
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - George A. Mashour
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Anthony G. Hudetz
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA,Corresponding authors. (Z. Huang), (A.G. Hudetz)
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8
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Bandarabadi M, Herrera CG, Gent TC, Bassetti C, Schindler K, Adamantidis AR. A role for spindles in the onset of rapid eye movement sleep. Nat Commun 2020; 11:5247. [PMID: 33067436 PMCID: PMC7567828 DOI: 10.1038/s41467-020-19076-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 09/21/2020] [Indexed: 12/17/2022] Open
Abstract
Sleep spindle generation classically relies on an interplay between the thalamic reticular nucleus (TRN), thalamo-cortical (TC) relay cells and cortico-thalamic (CT) feedback during non-rapid eye movement (NREM) sleep. Spindles are hypothesized to stabilize sleep, gate sensory processing and consolidate memory. However, the contribution of non-sensory thalamic nuclei in spindle generation and the role of spindles in sleep-state regulation remain unclear. Using multisite thalamic and cortical LFP/unit recordings in freely behaving mice, we show that spike-field coupling within centromedial and anterodorsal (AD) thalamic nuclei is as strong as for TRN during detected spindles. We found that spindle rate significantly increases before the onset of rapid eye movement (REM) sleep, but not wakefulness. The latter observation is consistent with our finding that enhancing spontaneous activity of TRN cells or TRN-AD projections using optogenetics increase spindle rate and transitions to REM sleep. Together, our results extend the classical TRN-TC-CT spindle pathway to include non-sensory thalamic nuclei and implicate spindles in the onset of REM sleep. During NREM sleep, spindles emerge from thalamocortical interactions. Here the authors carry out multisite thalamic and cortical recordings in freely behaving mice, to investigate the role of other non-classical thalamic sites in sleep spindle generation.
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Affiliation(s)
- Mojtaba Bandarabadi
- Department of Neurology, Zentrum für Experimentelle Neurologie, Inselspital University Hospital Bern, Bern, Switzerland.,Department of Neurology, Sleep-Wake-Epilepsy Center, Inselspital University Hospital Bern, Bern, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Carolina Gutierrez Herrera
- Department of Neurology, Zentrum für Experimentelle Neurologie, Inselspital University Hospital Bern, Bern, Switzerland.,Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Thomas C Gent
- Department of Neurology, Zentrum für Experimentelle Neurologie, Inselspital University Hospital Bern, Bern, Switzerland.,Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Claudio Bassetti
- Department of Neurology, Zentrum für Experimentelle Neurologie, Inselspital University Hospital Bern, Bern, Switzerland.,Department of Neurology, Sleep-Wake-Epilepsy Center, Inselspital University Hospital Bern, Bern, Switzerland
| | - Kaspar Schindler
- Department of Neurology, Zentrum für Experimentelle Neurologie, Inselspital University Hospital Bern, Bern, Switzerland.,Department of Neurology, Sleep-Wake-Epilepsy Center, Inselspital University Hospital Bern, Bern, Switzerland
| | - Antoine R Adamantidis
- Department of Neurology, Zentrum für Experimentelle Neurologie, Inselspital University Hospital Bern, Bern, Switzerland. .,Department of Neurology, Sleep-Wake-Epilepsy Center, Inselspital University Hospital Bern, Bern, Switzerland. .,Department of Biomedical Research, University of Bern, Bern, Switzerland.
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9
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TRPM4 Conductances in Thalamic Reticular Nucleus Neurons Generate Persistent Firing during Slow Oscillations. J Neurosci 2020; 40:4813-4823. [PMID: 32414784 DOI: 10.1523/jneurosci.0324-20.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/13/2020] [Accepted: 05/11/2020] [Indexed: 12/21/2022] Open
Abstract
During sleep, neurons in the thalamic reticular nucleus (TRN) participate in distinct types of oscillatory activity. While the reciprocal synaptic circuits between TRN and sensory relay nuclei are known to underlie the generation of sleep spindles, the mechanisms regulating slow (<1 Hz) forms of thalamic oscillations are not well understood. Under in vitro conditions, TRN neurons can generate slow oscillations in a cell-intrinsic manner, with postsynaptic Group 1 metabotropic glutamate receptor activation triggering long-lasting plateau potentials thought to be mediated by both T-type Ca2+ currents and Ca2+-activated nonselective cation currents (ICAN). However, the identity of ICAN and the possible contribution of thalamic circuits to slow rhythmic activity remain unclear. Using thalamic slices derived from adult mice of either sex, we recorded slow forms of rhythmic activity in TRN neurons, which were driven by fast glutamatergic thalamoreticular inputs but did not require postsynaptic Group 1 metabotropic glutamate receptor activation. For a significant fraction of TRN neurons, synaptic inputs or brief depolarizing current steps led to long-lasting plateau potentials and persistent firing (PF), and in turn, resulted in sustained synaptic inhibition in postsynaptic relay neurons of the ventrobasal thalamus (VB). Pharmacological approachesindicated that plateau potentials were triggered by Ca2+ influx through T-type Ca2+ channels and mediated by Ca2+- and voltage-dependent transient receptor potential melastatin 4 (TRPM4) channels. Together, our results suggest that thalamic circuits can generate slow oscillatory activity, mediated by an interplay of TRN-VB synaptic circuits that generate rhythmicity and TRN cell-intrinsic mechanisms that control PF and oscillation frequency.SIGNIFICANCE STATEMENT Slow forms of thalamocortical rhythmic activity are thought to be essential for memory consolidation during sleep and the efficient removal of potentially toxic metabolites. In vivo, thalamic slow oscillations are regulated by strong bidirectional synaptic pathways linking neocortex and thalamus. Therefore, in vitro studies in the isolated thalamus offer important insights about the ability of individual neurons and local circuits to generate different forms of rhythmic activity. We found that circuits formed by GABAergic neurons in the thalamic reticular nucleus and glutamatergic relay neurons in the ventrobasal thalamus generated slow oscillatory activity, which was accompanied by persistent firing in thalamic reticular nucleus neurons. Our results identify both cell-intrinsic and synaptic mechanisms that mediate slow forms of rhythmic activity in thalamic circuits.
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10
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Méndez-Fernández A, Moreno-Castillo M, Huidobro N, Flores A, Manjarrez E. Afterdischarges of Spinal Interneurons Following a Brief High-Frequency Stimulation of Ia Afferents in the Cat. Front Integr Neurosci 2020; 13:75. [PMID: 32038185 PMCID: PMC6992651 DOI: 10.3389/fnint.2019.00075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 12/16/2019] [Indexed: 11/13/2022] Open
Abstract
Spinal motoneurons exhibit sustained afterdischarges and plateau potentials following a brief high-frequency stimulation of Ia afferents. Also, there is evidence that spinal cord interneurons exhibit plateau potentials. However, to our knowledge, there are no reports about the possible afterdischarge behavior of lumbar spinal interneurons activated by Ia afferents. Given that there are spinal interneurons receiving monosynaptic inputs from Ia afferents, these cells could then be activated in parallel to motoneurons after repetitive muscle stretch. We explored this possibility in cats with a precollicular-postmammillary decerebration. We found that a brief high-frequency stimulation of Ia afferents produces afterdischarges that are highly correlated to a DC slow potential recorded at the cord dorsum. We conclude that in the cat spinal cord, not only the motoneurons but also the interneurons from the superficial and deep dorsal horn produce sustained afterdischarges, thus highlighting the importance of interneurons in the spinal neuronal circuitry. The significance of our finding is that it opens the possibility that the spinal cord interneurons activated by Ia afferents could also exhibit bistability, a relevant phenomenon well-characterized in the motoneurons.
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Affiliation(s)
| | | | - Nayeli Huidobro
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México
| | - Amira Flores
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México
| | - Elias Manjarrez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México
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11
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Abstract
Recent data have shown that sleep plays a beneficial role for cognitive functions such as declarative memory consolidation and perceptual learning. In this article, we review recent findings on the role of sleep in promoting adaptive visual response changes in the lateral geniculate nucleus and primary visual cortex following novel visual experiences. We discuss these findings in the context of what is currently known about how sleep affects the activity and function of thalamocortical circuits and current hypotheses regarding how sleep facilitates synaptic plasticity.
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Affiliation(s)
- Jaclyn M Durkin
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Sara J Aton
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA;
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12
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Biophysical modeling of C. elegans neurons: Single ion currents and whole-cell dynamics of AWCon and RMD. PLoS One 2019; 14:e0218738. [PMID: 31260485 PMCID: PMC6602206 DOI: 10.1371/journal.pone.0218738] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 06/07/2019] [Indexed: 01/28/2023] Open
Abstract
C. elegans neuronal system constitutes the ideal framework for studying simple, yet realistic, neuronal activity, since the whole nervous system is fully characterized with respect to the exact number of neurons and the neuronal connections. Most recent efforts are devoted to investigate and clarify the signal processing and functional connectivity, which are at the basis of sensing mechanisms, signal transmission, and motor control. In this framework, a refined modelof whole neuron dynamics constitutes a key ingredient to describe the electrophysiological processes, both at thecellular and at the network scale. In this work, we present Hodgkin-Huxley-based models of ion channels dynamics black, built on data available both from C. elegans and from other organisms, expressing homologous channels. We combine these channel models to simulate the electrical activity oftwo among the most studied neurons in C. elegans, which display prototypical dynamics of neuronal activation, the chemosensory AWCON and the motor neuron RMD. Our model properly describes the regenerative responses of the two cells. We analyze in detail the role of ion currents, both in wild type and in in silico knockout neurons. Moreover, we specifically investigate the behavior of RMD, identifying a heterogeneous dynamical response which includes bistable regimes and sustained oscillations. We are able to assess the critical role of T-type calcium currents, carried by CCA-1 channels, and leakage currents in the regulation of RMD response. Overall, our results provide new insights in the activity of key C. elegans neurons. The developed mathematical framework constitute a basis for single-cell and neuronal networks analyses, opening new scenarios in the in silico modeling of C. elegans neuronal system.
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The resilient brain and the guardians of sleep: New perspectives on old assumptions. Sleep Med Rev 2018; 39:98-107. [DOI: 10.1016/j.smrv.2017.08.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/19/2017] [Accepted: 08/17/2017] [Indexed: 12/24/2022]
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14
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Parker J, Bondy B, Prilutsky BI, Cymbalyuk G. Control of transitions between locomotor-like and paw shake-like rhythms in a model of a multistable central pattern generator. J Neurophysiol 2018; 120:1074-1089. [PMID: 29766765 DOI: 10.1152/jn.00696.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The ability of the same neuronal circuit to control different motor functions is an actively debated concept. Previously, we showed in a model that a single multistable central pattern generator (CPG) could produce two different rhythmic motor patterns, slow and fast, corresponding to cat locomotion and paw shaking. A locomotor-like rhythm (~1 Hz) and a paw shake-like rhythm (~10 Hz) did coexist in our model, and, by applying a single pulse of current, we could switch the CPG from one regime to another (Bondy B, Klishko AN, Edwards DH, Prilutsky BI, Cymbalyuk G. In: Neuromechanical Modeling of Posture and Locomotion, 2016). Here we investigated the roles of slow intrinsic ionic currents in this multistability. The CPG is modeled as a half-center oscillator circuit comprising two reciprocally inhibitory neurons. Each neuron is equipped with two slow inward currents, a Na+ current ( INaS) and a Ca2+ current ( ICaS). ICaS inactivates much more slowly and at more hyperpolarized voltages than INaS. We demonstrate that INaS is the primary current driving the paw shake-like bursting. ICaS is crucial for the locomotor-like bursting, and it is inactivated during the paw shake-like activity. We investigate the sensitivity of the bursting regimes to perturbations, using a pulse of current to induce a switch from one regime to the other, and we demonstrate that the transition duration is dependent on pulse amplitude and application phase. We also investigate the modulatory roles of the strength of various currents on characteristics of these rhythms and show that their effects are regime specific. We conclude that a multistable CPG is physiologically plausible and derive testable predictions of the model. NEW & NOTEWORTHY Little is known about how a single central pattern generator could produce multiple rhythms. We describe a novel mechanism for multistability of bursting regimes with strongly distinct periods. The proposed mechanism emphasizes the role of intrinsic cellular dynamics over synaptic dynamics in the production of multistability. We describe how the temporal characteristics of multiple rhythms could be controlled by neuromodulation and how single pulses of current could produce a switch between regimes in a functional fashion.
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Affiliation(s)
- Jessica Parker
- Neuroscience Institute, Georgia State University , Atlanta, Georgia
| | - Brian Bondy
- Neuroscience Institute, Georgia State University , Atlanta, Georgia.,Institute for Neuroscience, University of Texas , Austin, Texas
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, Georgia
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15
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Dashevskiy T, Cymbalyuk G. Propensity for Bistability of Bursting and Silence in the Leech Heart Interneuron. Front Comput Neurosci 2018; 12:5. [PMID: 29467641 PMCID: PMC5808133 DOI: 10.3389/fncom.2018.00005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 01/12/2018] [Indexed: 12/15/2022] Open
Abstract
The coexistence of neuronal activity regimes has been reported under normal and pathological conditions. Such multistability could enhance the flexibility of the nervous system and has many implications for motor control, memory, and decision making. Multistability is commonly promoted by neuromodulation targeting specific membrane ionic currents. Here, we investigated how modulation of different ionic currents could affect the neuronal propensity for bistability. We considered a leech heart interneuron model. It exhibits bistability of bursting and silence in a narrow range of the leak current parameters, conductance (gleak) and reversal potential (Eleak). We assessed the propensity for bistability of the model by using bifurcation diagrams. On the diagram (gleak, Eleak), we mapped bursting and silent regimes. For the canonical value of Eleak we determined the range of gleak which supported the bistability. We use this range as an index of propensity for bistability. We investigated how this index was affected by alterations of ionic currents. We systematically changed their conductances, one at a time, and built corresponding bifurcation diagrams in parameter planes of the maximal conductance of a given current and the leak conductance. We found that conductance of only one current substantially affected the index of propensity; the increase of the maximal conductance of the hyperpolarization-activated cationic current increased the propensity index. The second conductance with the strongest effect was the conductance of the low-threshold fast Ca2+ current; its reduction increased the propensity index although the effect was about two times smaller in magnitude. Analyzing the model with both changes applied simultaneously, we found that the diagram (gleak, Eleak) showed a progressively expanded area of bistability of bursting and silence.
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Affiliation(s)
- Tatiana Dashevskiy
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Gennady Cymbalyuk
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
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16
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Higashikubo B, Moore CI. Systematic examination of the impact of depolarization duration on thalamic reticular nucleus firing in vivo. Neuroscience 2017; 368:187-198. [PMID: 28965837 DOI: 10.1016/j.neuroscience.2017.09.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 09/15/2017] [Accepted: 09/21/2017] [Indexed: 01/09/2023]
Abstract
The thalamic reticular nucleus (TRN) is optimally positioned to regulate information processing and state dynamics in dorsal thalamus. Distinct inputs depolarize TRN on multiple time scales, including thalamocortical afferents, corticothalamic 'feedback', and neuromodulation. Here, we systematically tested the concurrent and after-effects of depolarization duration on TRN firing in vivo using selective optogenetic drive. In VGAT-ChR2 mice, we isolated TRN single units (SU: N = 100 neurons) that responded at brief latency (≤5 ms) to stimulation. These units, and multi-unit activity (MUA) on corresponding electrodes, were analyzed in detail. Consistent with prior findings in relay neurons, after light cessation, burst-like events occurred in 74% of MUA sites, and 16% of SU. Increasing optical duration from 2 to 330 ms enhanced this burst probability, and decreased the latency to the first burst after stimulation. During stimulation, neurons demonstrated a 'plateau' firing response lasting 20-30 ms in response to light, but significant heterogeneity existed in the minimal stimuli required to drive this response. Two distinct types were evident, more sensitive 'non-linear' neurons that were driven to the plateau response by 2 or 5 ms pulses, versus 'linear' neurons that fired proportionally to optical duration, and reached the plateau with ∼20-ms optical drive. Non-linear neurons showed higher evoked firing rates and burst probability, but spontaneous rate did not differ between types. These findings provide direct predictions for TRN responses to a range of natural depolarizing inputs, and a guide for the optical control of this key structure in studies of network function and behavior.
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Affiliation(s)
- Bryan Higashikubo
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Neuroscience, Brown University, Providence, RI 02912-1978, USA
| | - Christopher I Moore
- Brown Institute for Brain Science, Brown University, Providence, RI 02912-1978, USA; Department of Neuroscience, Brown University, Providence, RI 02912-1978, USA.
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17
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Form and Function of Sleep Spindles across the Lifespan. Neural Plast 2016; 2016:6936381. [PMID: 27190654 PMCID: PMC4848449 DOI: 10.1155/2016/6936381] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 03/16/2016] [Indexed: 01/11/2023] Open
Abstract
Since the advent of EEG recordings, sleep spindles have been identified as hallmarks of non-REM sleep. Despite a broad general understanding of mechanisms of spindle generation gleaned from animal studies, the mechanisms underlying certain features of spindles in the human brain, such as “global” versus “local” spindles, are largely unknown. Neither the topography nor the morphology of sleep spindles remains constant throughout the lifespan. It is likely that changes in spindle phenomenology during development and aging are the result of dramatic changes in brain structure and function. Across various developmental windows, spindle activity is correlated with general cognitive aptitude, learning, and memory; however, these correlations vary in strength, and even direction, depending on age and metrics used. Understanding these differences across the lifespan should further clarify how these oscillations are generated and their function under a variety of circumstances. We discuss these issues, and their translational implications for human cognitive function. Because sleep spindles are similarly affected in disorders of neurodevelopment (such as schizophrenia) and during aging (such as neurodegenerative conditions), both types of disorders may benefit from therapies based on a better understanding of spindle function.
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Herreras O, Makarova J, Makarov VA. New uses of LFPs: Pathway-specific threads obtained through spatial discrimination. Neuroscience 2015; 310:486-503. [PMID: 26415769 DOI: 10.1016/j.neuroscience.2015.09.054] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/16/2015] [Accepted: 09/19/2015] [Indexed: 11/27/2022]
Abstract
Local field potentials (LFPs) reflect the coordinated firing of functional neural assemblies during information coding and transfer across neural networks. As such, it was proposed that the extraordinary variety of cytoarchitectonic elements in the brain is responsible for the wide range of amplitudes and for the coverage of field potentials, which in most cases receive contributions from multiple pathways and populations. The influence of spatial factors overrides the bold interpretations of customary measurements, such as the amplitude and polarity, to the point that their cellular interpretation is one of the hardest tasks in Neurophysiology. Temporal patterns and frequency bands are not exclusive to pathways but rather, the spatial configuration of the voltage gradients created by each pathway is highly specific and may be used advantageously. Recent technical and analytical advances now make it possible to separate and then reconstruct activity for specific pathways. In this review, we discuss how spatial features specific to cells and populations define the amplitude and extension of LFPs, why they become virtually indecipherable when several pathways are co-activated, and then we present the recent advances regarding their disentanglement using spatial discrimination techniques. The pathway-specific threads of LFPs have a simple cellular interpretation, and the temporal fluctuations obtained can be applied to a variety of new experimental objectives and improve existing approaches. Among others, they facilitate the parallel readout of activity in several populations over multiple time scales correlating them with behavior. Also, they access information contained in irregular fluctuations, facilitating the testing of ongoing plasticity. In addition, they open the way to unravel the synaptic nature of rhythmic oscillations, as well as the dynamic relationships between multiple oscillatory activities. The challenge of understanding which waves belong to which populations, and the pathways that provoke them, may soon be overcome.
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Affiliation(s)
- O Herreras
- Department of Systems Neuroscience, Cajal Institute, CSIC, Avenida Doctor Arce 37, Madrid 28002, Spain.
| | - J Makarova
- Department of Systems Neuroscience, Cajal Institute, CSIC, Avenida Doctor Arce 37, Madrid 28002, Spain.
| | - V A Makarov
- Department of Applied Mathematics, School of Mathematics, University Complutense of Madrid, Plaza de Ciencias 3, Ciudad Universitaria, Madrid 28040, Spain.
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Wendt SL, Welinder P, Sorensen HBD, Peppard PE, Jennum P, Perona P, Mignot E, Warby SC. Inter-expert and intra-expert reliability in sleep spindle scoring. Clin Neurophysiol 2014; 126:1548-56. [PMID: 25434753 DOI: 10.1016/j.clinph.2014.10.158] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 09/20/2014] [Accepted: 10/29/2014] [Indexed: 01/13/2023]
Abstract
OBJECTIVES To measure the inter-expert and intra-expert agreement in sleep spindle scoring, and to quantify how many experts are needed to build a reliable dataset of sleep spindle scorings. METHODS The EEG dataset was comprised of 400 randomly selected 115s segments of stage 2 sleep from 110 sleeping subjects in the general population (57±8, range: 42-72 years). To assess expert agreement, a total of 24 Registered Polysomnographic Technologists (RPSGTs) scored spindles in a subset of the EEG dataset at a single electrode location (C3-M2). Intra-expert and inter-expert agreements were calculated as F1-scores, Cohen's kappa (κ), and intra-class correlation coefficient (ICC). RESULTS We found an average intra-expert F1-score agreement of 72±7% (κ: 0.66±0.07). The average inter-expert agreement was 61±6% (κ: 0.52±0.07). Amplitude and frequency of discrete spindles were calculated with higher reliability than the estimation of spindle duration. Reliability of sleep spindle scoring can be improved by using qualitative confidence scores, rather than a dichotomous yes/no scoring system. CONCLUSIONS We estimate that 2-3 experts are needed to build a spindle scoring dataset with 'substantial' reliability (κ: 0.61-0.8), and 4 or more experts are needed to build a dataset with 'almost perfect' reliability (κ: 0.81-1). SIGNIFICANCE Spindle scoring is a critical part of sleep staging, and spindles are believed to play an important role in development, aging, and diseases of the nervous system.
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Affiliation(s)
- Sabrina L Wendt
- Center for Sleep Science and Medicine, Stanford University, Palo Alto, CA, United States; Danish Center for Sleep Medicine, Glostrup University Hospital, DK-2600 Glostrup, Denmark
| | - Peter Welinder
- Computational Vision Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Helge B D Sorensen
- Dept. of Electrical Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Paul E Peppard
- Department of Population Health Sciences, University of Wisconsin - Madison, Madison, WI, United States
| | - Poul Jennum
- Danish Center for Sleep Medicine, Glostrup University Hospital, DK-2600 Glostrup, Denmark
| | - Pietro Perona
- Computational Vision Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Emmanuel Mignot
- Center for Sleep Science and Medicine, Stanford University, Palo Alto, CA, United States
| | - Simon C Warby
- Center for Sleep Science and Medicine, Stanford University, Palo Alto, CA, United States; Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Department of Psychiatry, Université de Montréal, Montréal, Canada.
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20
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Abstract
It is widely accepted that corticothalamic neurons recruit the thalamus in slow oscillation, but global slow-wave thalamocortical dynamics have never been experimentally shown. We analyzed intracellular activities of neurons either from different cortical areas or from a variety of specific and nonspecific thalamic nuclei in relation to the phase of global EEG signal in ketamine-xylazine anesthetized mice. We found that, on average, slow-wave active states started off within frontal cortical areas as well as higher-order and intralaminar thalamus (posterior and parafascicular nuclei) simultaneously. Then, the leading edge of active states propagated in the anteroposterior/lateral direction over the cortex at ∼40 mm/s. The latest structure we recorded within the slow-wave cycle was the anterior thalamus, which followed active states of the retrosplenial cortex. Active states from different cortical areas tended to terminate simultaneously. Sensory thalamic ventral posterior medial and lateral geniculate nuclei followed cortical active states with major inhibitory and weak tonic-like "modulator" EPSPs. In these nuclei, sharp-rising, large-amplitude EPSPs ("drivers") were not modulated by cortical slow waves, suggesting their origin in ascending pathways. The thalamic active states in other investigated nuclei were composed of depolarization: some revealing "driver"- and "modulator"-like EPSPs, others showing "modulator"-like EPSPs only. We conclude that sensory thalamic nuclei follow the propagating cortical waves, whereas neurons from higher-order thalamic nuclei display "hub dynamics" and thus may contribute to the generation of cortical slow waves.
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21
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Interpreting EEG alpha activity. Neurosci Biobehav Rev 2014; 44:94-110. [DOI: 10.1016/j.neubiorev.2013.05.007] [Citation(s) in RCA: 259] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 04/05/2013] [Accepted: 05/03/2013] [Indexed: 01/04/2023]
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22
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Chen Y, Parker WD, Wang K. The role of T-type calcium channel genes in absence seizures. Front Neurol 2014; 5:45. [PMID: 24847307 PMCID: PMC4023043 DOI: 10.3389/fneur.2014.00045] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 03/24/2014] [Indexed: 12/05/2022] Open
Abstract
The thalamic relay neurons, reticular thalamic nucleus, and neocortical pyramidal cells form a circuit that sustains oscillatory burst firing, and is regarded as the underlying mechanism of absence seizures. T-type calcium channels play a key role in this circuit. Here, we review the role of T-type calcium channel genes in the development of absence seizures, and emphasize gain or loss of function mutations, and other variations that alter both quantity and quality of transcripts, and methylation status of isoforms of T-type calcium channel proteins might be of equal importance in understanding the pathological mechanism of absence seizures.
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Affiliation(s)
- Yucai Chen
- University of Illinois at Chicago , Peoria, IL , USA
| | | | - Keling Wang
- Hebei Children Hospital , Shijiazhuang , China
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23
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Guan YZ, Liu SQ, Zeng YJ. Gradient Trigger Mechanisms Related to Bistability Regimes in a Leech Heartbeat Model. NEUROPHYSIOLOGY+ 2014. [DOI: 10.1007/s11062-014-9415-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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24
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Kimura A. Diverse subthreshold cross-modal sensory interactions in the thalamic reticular nucleus: implications for new pathways of cross-modal attentional gating function. Eur J Neurosci 2014; 39:1405-18. [PMID: 24646412 DOI: 10.1111/ejn.12545] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 01/26/2014] [Accepted: 02/03/2014] [Indexed: 11/30/2022]
Abstract
Our attention to a sensory cue of a given modality interferes with attention to a sensory cue of another modality. However, an object emitting various sensory cues attracts attention more effectively. The thalamic reticular nucleus (TRN) could play a pivotal role in such cross-modal modulation of attention given that cross-modal sensory interaction takes place in the TRN, because the TRN occupies a highly strategic position to function in the control of gain and/or gating of sensory processing in the thalamocortical loop. In the present study cross-modal interactions between visual and auditory inputs were examined in single TRN cells of anesthetised rats using juxta-cellular recording and labeling techniques. Visual or auditory responses were modulated by subthreshold sound or light stimuli, respectively, in the majority of recordings (46 of 54 visual and 60 of 73 auditory cells). However, few bimodal sensory cells were found. Cells showing modulation of the sensory response were distributed in the whole visual and auditory sectors of the TRN. Modulated cells sent axonal projections to first-order or higher-order thalamic nuclei. Suppression predominated in modulation that took place not only in primary responses but also in late responses repeatedly evoked after sensory stimulation. Combined sensory stimulation also evoked de-novo responses, and modulated response latency and burst spiking. These results indicate that the TRN incorporates sensory inputs of different modalities into single cell activity to function in sensory processing in the lemniscal and non-lemniscal systems. This raises the possibility that the TRN constitutes neural pathways involved in cross-modal attentional gating.
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Affiliation(s)
- Akihisa Kimura
- Department of Physiology, Wakayama Medical University, Wakayama Kimiidera 811-1, Wakayama, 641-8509, Japan
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25
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Role of cardiorespiratory synchronization and sleep physiology: effects on membrane potential in the restorative functions of sleep. Sleep Med 2014; 15:279-88. [DOI: 10.1016/j.sleep.2013.10.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/18/2013] [Accepted: 10/19/2013] [Indexed: 01/26/2023]
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26
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Sleep spindles are generated in the absence of T-type calcium channel-mediated low-threshold burst firing of thalamocortical neurons. Proc Natl Acad Sci U S A 2013; 110:20266-71. [PMID: 24282303 DOI: 10.1073/pnas.1320572110] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
T-type Ca(2+) channels in thalamocortical (TC) neurons have long been considered to play a critical role in the genesis of sleep spindles, one of several TC oscillations. A classical model for TC oscillations states that reciprocal interaction between synaptically connected GABAergic thalamic reticular nucleus (TRN) neurons and glutamatergic TC neurons generates oscillations through T-type channel-mediated low-threshold burst firings of neurons in the two nuclei. These oscillations are then transmitted from TC neurons to cortical neurons, contributing to the network of TC oscillations. Unexpectedly, however, we found that both WT and KO mice for CaV3.1, the gene for T-type Ca(2+) channels in TC neurons, exhibit typical waxing-and-waning sleep spindle waves at a similar occurrence and with similar amplitudes and episode durations during non-rapid eye movement sleep. Single-unit recording in parallel with electroencephalography in vivo confirmed a complete lack of burst firing in the mutant TC neurons. Of particular interest, the tonic spike frequency in TC neurons was significantly increased during spindle periods compared with nonspindle periods in both genotypes. In contrast, no significant change in burst firing frequency between spindle and nonspindle periods was noted in the WT mice. Furthermore, spindle-like oscillations were readily generated within intrathalamic circuits composed solely of TRN and TC neurons in vitro in both the KO mutant and WT mice. Our findings call into question the essential role of low-threshold burst firings in TC neurons and suggest that tonic firing is important for the generation and propagation of spindle oscillations in the TC circuit.
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27
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Joiner WJ, Friedman EB, Hung HT, Koh K, Sowcik M, Sehgal A, Kelz MB. Genetic and anatomical basis of the barrier separating wakefulness and anesthetic-induced unresponsiveness. PLoS Genet 2013; 9:e1003605. [PMID: 24039590 PMCID: PMC3764144 DOI: 10.1371/journal.pgen.1003605] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 05/20/2013] [Indexed: 01/30/2023] Open
Abstract
A robust, bistable switch regulates the fluctuations between wakefulness and natural sleep as well as those between wakefulness and anesthetic-induced unresponsiveness. We previously provided experimental evidence for the existence of a behavioral barrier to transitions between these states of arousal, which we call neural inertia. Here we show that neural inertia is controlled by processes that contribute to sleep homeostasis and requires four genes involved in electrical excitability: Sh, sss, na and unc79. Although loss of function mutations in these genes can increase or decrease sensitivity to anesthesia induction, surprisingly, they all collapse neural inertia. These effects are genetically selective: neural inertia is not perturbed by loss-of-function mutations in all genes required for the sleep/wake cycle. These effects are also anatomically selective: sss acts in different neurons to influence arousal-promoting and arousal-suppressing processes underlying neural inertia. Supporting the idea that anesthesia and sleep share some, but not all, genetic and anatomical arousal-regulating pathways, we demonstrate that increasing homeostatic sleep drive widens the neural inertial barrier. We propose that processes selectively contributing to sleep homeostasis and neural inertia may be impaired in pathophysiological conditions such as coma and persistent vegetative states. An annual 234 million surgical procedures are performed worldwide, making general anesthetics among the most common drugs administered to humans. Remarkably, however, we still do not understand the mechanisms by which general anesthetics render patients unconscious or the processes that re-establish consciousness upon emergence from anesthesia. We previously showed that the brain resists transitions between the wakeful and anesthesia states by generating a barrier to such transitions in both directions. We also showed that the existence of this barrier is conserved from invertebrates to mammals. In our present work, we use the genetic tractability and the simplified nervous system of the fruit fly Drosophila melanogaster to show that four genes are required to maintain this barrier. We also show that, as in mammals, there is overlap between pathways regulating natural sleep and general anesthesia. We propose that some of these shared pathways are impaired in conditions such as coma and persistent vegetative states, in which the barrier to transitioning to the waking state appears to be insurmountable.
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Affiliation(s)
- William J. Joiner
- Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America
| | - Eliot B. Friedman
- Department of Neuroscience, Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Hsiao-Tung Hung
- Department of Neuroscience, Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Kyunghee Koh
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Mallory Sowcik
- Department of Neuroscience, Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Amita Sehgal
- Department of Neuroscience, Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Max B. Kelz
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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28
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Liang X, Yanchuk S, Zhao L. Gating-signal propagation by a feed-forward neural motif. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:012910. [PMID: 23944541 DOI: 10.1103/physreve.88.012910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 07/10/2013] [Indexed: 06/02/2023]
Abstract
We study the signal propagation in a feed-forward motif consisting of three bistable neurons: Two input neurons receive input signals and the third output neuron generates the output. We find that a weak input signal can be propagated from the input neurons to the output neuron without amplitude attenuation. We further reveal that the initial states of the input neurons and the coupling strength act as signal gates and determine whether the propagation is enhanced or not. We also investigate the effect of the input signal frequency on enhanced signal propagation.
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Affiliation(s)
- Xiaoming Liang
- School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
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29
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A balance equation determines a switch in neuronal excitability. PLoS Comput Biol 2013; 9:e1003040. [PMID: 23717194 PMCID: PMC3662658 DOI: 10.1371/journal.pcbi.1003040] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 03/06/2013] [Indexed: 11/19/2022] Open
Abstract
We use the qualitative insight of a planar neuronal phase portrait to detect an excitability switch in arbitrary conductance-based models from a simple mathematical condition. The condition expresses a balance between ion channels that provide a negative feedback at resting potential (restorative channels) and those that provide a positive feedback at resting potential (regenerative channels). Geometrically, the condition imposes a transcritical bifurcation that rules the switch of excitability through the variation of a single physiological parameter. Our analysis of six different published conductance based models always finds the transcritical bifurcation and the associated switch in excitability, which suggests that the mathematical predictions have a physiological relevance and that a same regulatory mechanism is potentially involved in the excitability and signaling of many neurons. Understanding the changing electrophysiological signatures of neurons in different physiological and pharmacological conditions is a central focus of experimental electrophysiology because a key component of cell signaling in the nervous system. Computational modeling may assist experimentalists in this quest by identifying core mechanisms and suggesting pharmacological targets from a mathematical analysis of the model. But a successful interplay between experiments and mathematical predictions requires new analysis tools adapted to the complexity of high-dimensional computational models nowadays available. We use bifurcation theory to propose a mathematical condition that can detect an important switch of neuronal excitability in arbitrary conductance-based neuronal models and we illustrate its physiological relevance in six published state-of-the art models of different neurons.
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Bazanova O. Comments for Current Interpretation EEG Alpha Activity: A Review and Analysis. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/jbbs.2012.22027] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Malashchenko T, Shilnikov A, Cymbalyuk G. Bistability of bursting and silence regimes in a model of a leech heart interneuron. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:041910. [PMID: 22181178 DOI: 10.1103/physreve.84.041910] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 05/03/2011] [Indexed: 05/31/2023]
Abstract
Bursting is one of the primary activity regimes of neurons. Our study is focused on determining a generic biophysical mechanism underlying the coexistence of the bursting and silent regimes observed in a neuron model. We show that the main ingredient for this mechanism is a saddle periodic orbit. The stable manifold of the orbit sets a threshold between the regimes of activity. Thus, the range of the controlling parameters, where the coexistence is observed, is limited by the bifurcations' values at which the saddle orbit appears and disappears. We show that it appears through the subcritical Andronov-Hopf bifurcation, where the equilibrium representing the silent regime loses stability, and disappears at the homoclinic bifurcation. Correspondingly, the bursting regime disappears in close proximity to the homoclinic bifurcation.
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Affiliation(s)
- Tatiana Malashchenko
- Neuroscience Institute, Georgia State University, 100 Piedmont Avenue SE, Atlanta, Georgia 30303, USA
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Timofeev I. Neuronal plasticity and thalamocortical sleep and waking oscillations. PROGRESS IN BRAIN RESEARCH 2011; 193:121-44. [PMID: 21854960 DOI: 10.1016/b978-0-444-53839-0.00009-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Throughout life, thalamocortical (TC) network alternates between activated states (wake or rapid eye movement sleep) and slow oscillatory state dominating slow-wave sleep. The patterns of neuronal firing are different during these distinct states. I propose that due to relatively regular firing, the activated states preset some steady state synaptic plasticity and that the silent periods of slow-wave sleep contribute to a release from this steady state synaptic plasticity. In this respect, I discuss how states of vigilance affect short-, mid-, and long-term synaptic plasticity, intrinsic neuronal plasticity, as well as homeostatic plasticity. Finally, I suggest that slow oscillation is intrinsic property of cortical network and brain homeostatic mechanisms are tuned to use all forms of plasticity to bring cortical network to the state of slow oscillation. However, prolonged and profound shift from this homeostatic balance could lead to development of paroxysmal hyperexcitability and seizures as in the case of brain trauma.
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Affiliation(s)
- Igor Timofeev
- The Centre de recherche Université Laval Robert-Giffard (CRULRG), Laval University, Québec, Canada.
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Sleigh JW, Leslie K, Voss L. The effect of skin incision on the electroencephalogram during general anesthesia maintained with propofol or desflurane. J Clin Monit Comput 2010; 24:307-18. [DOI: 10.1007/s10877-010-9251-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2010] [Accepted: 07/20/2010] [Indexed: 11/28/2022]
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Kovács K, SÃk A, Ricketts C, Timofeev I. Subcellular distribution of low-voltage activated T-type Ca2+ channel subunits (Cav3.1 and Cav3.3) in reticular thalamic neurons of the cat. J Neurosci Res 2010; 88:448-60. [DOI: 10.1002/jnr.22200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wilson MT, Barry M, Reynolds JNJ, Crump WP, Steyn-Ross DA, Steyn-Ross ML, Sleigh JW. An analysis of the transitions between down and up states of the cortical slow oscillation under urethane anaesthesia. J Biol Phys 2009; 36:245-59. [PMID: 19960241 DOI: 10.1007/s10867-009-9180-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Accepted: 10/26/2009] [Indexed: 10/20/2022] Open
Abstract
We study the dynamics of the transition between the low- and high-firing states of the cortical slow oscillation by using intracellular recordings of the membrane potential from cortical neurons of rats. We investigate the evidence for a bistability in assemblies of cortical neurons playing a major role in the maintenance of this oscillation. We show that the trajectory of a typical transition takes an approximately exponential form, equivalent to the response of a resistor-capacitor circuit to a step-change in input. The time constant for the transition is negatively correlated with the membrane potential of the low-firing state, and values are broadly equivalent to neural time constants measured elsewhere. Overall, the results do not strongly support the hypothesis of a bistability in cortical neurons; rather, they suggest the cortical manifestation of the oscillation is a result of a step-change in input to the cortical neurons. Since there is evidence from previous work that a phase transition exists, we speculate that the step-change may be a result of a bistability within other brain areas, such as the thalamus, or a bistability among only a small subset of cortical neurons, or as a result of more complicated brain dynamics.
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Maex R, Steuber V. The first second: models of short-term memory traces in the brain. Neural Netw 2009; 22:1105-12. [PMID: 19635658 DOI: 10.1016/j.neunet.2009.07.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/26/2009] [Accepted: 07/14/2009] [Indexed: 10/20/2022]
Abstract
Many network models in computational neuroscience rise to the challenge of explaining behavioural phenomena ranging from microseconds to tens of seconds using components operating mostly on a time-scale of milliseconds. These models have in common that the underlying system has a memory, which implies that its output depends on its past input history. In this review we compare how such memory traces or delayed responses may be implemented in different brain areas supporting a diversity of functions.
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Affiliation(s)
- Reinoud Maex
- Science and Technology Research Institute, University of Hertfordshire, College Lane, Hatfield, Hertfordshire, United Kingdom.
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Olofsen E, Sleigh JW, Dahan A. Permutation entropy of the electroencephalogram: a measure of anaesthetic drug effect. Br J Anaesth 2008; 101:810-21. [PMID: 18852113 DOI: 10.1093/bja/aen290] [Citation(s) in RCA: 196] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND It would be useful to have an open-source electroencephalographic (EEG) index of gamma-amino-butyric acid (GABA)-ergic anaesthetic drug effect that is resistant to eye-blink artifact, responds rapidly to changes in EEG pattern, and can be linked to underlying neurophysiological and neuropharmacological mechanisms that control the conscious state. METHODS The EEG waveform can be described as a sequence of ordinal patterns. The permutation entropy (PE) describes the relative occurrence of each of these patterns. It is high ( approximately 1.0) when the signal has predominantly high frequencies and low ( approximately 0.4) when the signal consists of only low frequencies. The response of the PE to various computer-generated EEG-like waveforms was assessed. A composite PE index (CPEI) was developed, which was the sum of two simple PEs and included a small measurement-noise threshold (0.5 microV). We also applied the CPEI to two small pilot EEG data sets from patients receiving sevoflurane (n=21) or propofol (n=9) anaesthesia. RESULTS With minimal pre-processing or artifact rejection, the CPEI reliably tracked the anaesthetic-related EEG changes, namely loss of high frequencies, spindle-like waves, and delta waves. Using NONMEM, it was possible to construct adequate pharmacokinetic-pharmacodynamic models from the data. The CPEI was comparable with models derived using the bispectral index [BIS R(2)=0.88 (0.08) vs CPEI R(2)=0.91 (0.06) for the propofol data] and M-entropy indices [M-entropy R(2)=0.91 (0.06) vs CPEI R(2)=0.87 (0.09) for the sevoflurane data]. CONCLUSIONS PE of the EEG shows promise as a simple measure of GABAergic anaesthetic drug effect.
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Affiliation(s)
- E Olofsen
- Department of Anesthesiology, Leiden University Medical Center, Leiden University, Leiden, The Netherlands
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Broicher T, Kanyshkova T, Meuth P, Pape HC, Budde T. Correlation of T-channel coding gene expression, IT, and the low threshold Ca2+ spike in the thalamus of a rat model of absence epilepsy. Mol Cell Neurosci 2008; 39:384-99. [PMID: 18708145 DOI: 10.1016/j.mcn.2008.07.012] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 06/27/2008] [Accepted: 07/16/2008] [Indexed: 10/21/2022] Open
Abstract
T-type Ca(2+) current-dependent burst firing of thalamic neurons is thought to be involved in the hyper-synchronous activity observed during absence seizures. Here we investigate the correlation between the expression of T-channel coding genes (alpha1G, -H, -I), T-type Ca(2+) current, and the T-current-dependent low threshold Ca(2+) spike in three functionally distinct thalamic nuclei (lateral geniculate nucleus; centrolateral nucleus; reticular nucleus) in a rat model of absence epilepsy, the WAG/Rij rats, and a non-epileptic control strain, the ACI rats. The lateral geniculate nucleus and centrolateral nucleus were found to primarily express alpha1G and alpha1I, while the reticular thalamic nucleus expressed alpha1H and alpha1I. Expression was higher in WAG/Rij when compared to ACI. The T-type Ca(2+) current properties matched the predictions derived from the expression pattern analysis. Current density was larger in all nuclei of WAG/Rij rats when compared to ACI and correlated with LTS size and the minimum LTS generating slope, while T-type Ca(2+) current voltage dependency correlated with the LTS onset potential.
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Affiliation(s)
- Tilman Broicher
- Institut für Physiologie I, Westfälische Wilhelms-Universität Münster, Münster, Germany
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Multi-frequency auditory stimulation disrupts spindling activity in anesthetized animals. Neuroscience 2008; 151:888-900. [DOI: 10.1016/j.neuroscience.2007.11.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Revised: 10/16/2007] [Accepted: 12/06/2007] [Indexed: 11/17/2022]
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Cataldi M, Lariccia V, Marzaioli V, Cavaccini A, Curia G, Viggiano D, Canzoniero LMT, di Renzo G, Avoli M, Annunziato L. Zn2+ Slows Down CaV3.3 Gating Kinetics: Implications for Thalamocortical Activity. J Neurophysiol 2007; 98:2274-84. [PMID: 17699699 DOI: 10.1152/jn.00889.2006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We employed whole cell patch-clamp recordings to establish the effect of Zn2+ on the gating the brain specific, T-type channel isoform CaV3.3 expressed in HEK-293 cells. Zn2+ (300 μM) modified the gating kinetics of this channel without influencing its steady-state properties. When inward Ca2+ currents were elicited by step depolarizations at voltages above the threshold for channel opening, current inactivation was significantly slowed down while current activation was moderately affected. In addition, Zn2+ slowed down channel deactivation but channel recovery from inactivation was only modestly changed. Zn2+ also decreased whole cell Ca2+ permeability to 45% of control values. In the presence of Zn2+, Ca2+ currents evoked by mock action potentials were more persistent than in its absence. Furthermore, computer simulation of action potential generation in thalamic reticular cells performed to model the gating effect of Zn2+ on T-type channels (while leaving the kinetic parameters of voltage-gated Na+ and K+ unchanged) revealed that Zn2+ increased the frequency and the duration of burst firing, which is known to depend on T-type channel activity. In line with this finding, we discovered that chelation of endogenous Zn2+ decreased the frequency of occurrence of ictal-like epileptiform discharges in rat thalamocortical slices perfused with medium containing the convulsant 4-aminopyridine (50 μM). These data demonstrate that Zn2+ modulates CaV3.3 channel gating thus leading to increased neuronal excitability. We also propose that endogenous Zn2+ may have a role in controlling thalamocortical oscillations.
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Affiliation(s)
- M Cataldi
- Divisione di Farmacologia, Dipartimento di Neuroscienze, Facoltà di Medicina e Chirurgia, Università di Napoli Federico II, Naples, Italy
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Fojtiková D, Brázdil M, Horký J, Mikl M, Kuba R, Krupa P, Rektor I. Magnetic resonance spectroscopy of the thalamus in patients with typical absence epilepsy. Seizure 2006; 15:533-40. [PMID: 16877011 DOI: 10.1016/j.seizure.2006.06.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Revised: 05/29/2006] [Accepted: 06/13/2006] [Indexed: 10/24/2022] Open
Abstract
PURPOSE To investigate possible neuronal dysfunction of the thalamus in patients suffering from typical absence epilepsy, using magnetic resonance spectroscopy (MRS). Special attention was paid to levels of N-acetylaspartate (NAA) and creatine (Cr), and to the NAA/Cr ratio. METHODS MRS was performed over the right and left thalamus in nine patients suffering from typical absence epilepsy, and in nine sex- and age-matched healthy controls. All patients and controls were examined using a standard MRS-CSI (chemical shift imaging) technique. RESULTS Statistical analysis of the obtained data demonstrated a significantly lower thalamic NAA/Cr ratio in patients with typical absence epilepsy when compared to the healthy controls. Our MRS data showed symmetrical distribution of NAA/Cr ratio in the right and left thalamus within both the patient group and the group of healthy controls. No significant correlation between the patients' thalamic NAA/Cr values and the duration of the epilepsy or seizure frequency was revealed. CONCLUSIONS The present MRS data clearly indicate neuronal dysfunction in the thalami of patients with typical absence epilepsy. In agreement with other recent MRS findings in different idiopathic generalized epilepsy syndromes, our results confirm the role of the thalamus as an important structure in the pathogenesis of typical absence epilepsy.
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Affiliation(s)
- Dagmar Fojtiková
- Brno Epilepsy Centre, Department of Neurology, Masaryk University, St. Anne's University Hospital, Pekarská 53, 656 91 Brno, Czech Republic.
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Idoux E, Serafin M, Fort P, Vidal PP, Beraneck M, Vibert N, Mühlethaler M, Moore LE. Oscillatory and Intrinsic Membrane Properties of Guinea Pig Nucleus Prepositus Hypoglossi Neurons In Vitro. J Neurophysiol 2006; 96:175-96. [PMID: 16598060 DOI: 10.1152/jn.01355.2005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Numerous models of the oculomotor neuronal integrator located in the prepositus hypoglossi nucleus (PHN) involve both highly tuned recurrent networks and intrinsic neuronal properties; however, there is little experimental evidence for the relative role of these two mechanisms. The experiments reported here show that all PHN neurons (PHNn) show marked phasic behavior, which is highly oscillatory in ∼25% of the population. The behavior of this subset of PHNn, referred to as type D PHNn, is clearly different from that of the medial vestibular nucleus neurons, which transmit the bulk of head velocity-related sensory vestibular inputs without integrating them. We have investigated the firing and biophysical properties of PHNn and developed data-based realistic neuronal models to quantitatively illustrate that their active conductances can produce the oscillatory behavior. Although some individual type D PHNn are able to show some features of mathematical integration, the lack of robustness of this behavior strongly suggests that additional network interactions, likely involving all types of PHNn, are essential for the neuronal integrator. Furthermore, the relationship between the impulse activity and membrane potential of type D PHNn is highly nonlinear and frequency-dependent, even for relatively small-amplitude responses. These results suggest that some of the synaptic input to type D PHNn is likely to evoke oscillatory responses that will be nonlinearly amplified as the spike discharge rate increases. It would appear that the PHNn have specific intrinsic properties that, in conjunction with network interconnections, enhance the persistent neural activity needed for their function.
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Affiliation(s)
- Erwin Idoux
- Laboratoire de Neurobiologie des Réseaux Sensorimoteurs, Centre National de la Recherche Scientifique (CNRS)-Université René Descartes (Paris 5) Unité Mixte de Recherche (UMR) 7060, Paris, France
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Abstract
The idiopathic generalized epilepsies encompass a class of epileptic seizure types that exhibit a polygenic and heritable etiology. Advances in molecular biology and genetics have implicated defects in certain types of voltage-gated calcium channels and their ancillary subunits as important players in this form of epilepsy. Both T-type and P/Q-type channels appear to mediate important contributions to seizure genesis, modulation of network activity, and genetic seizure susceptibility. Here, we provide a comprehensive overview of the roles of these channels and associated subunits in normal and pathological brain activity within the context of idiopathic generalized epilepsy.
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Affiliation(s)
- Houman Khosravani
- Department of Physiology and Biophysics, Hotchkiss Brain Institute, University of Calgary, Canada
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Crunelli V, Cope DW, Hughes SW. Thalamic T-type Ca2+ channels and NREM sleep. Cell Calcium 2006; 40:175-90. [PMID: 16777223 PMCID: PMC3018590 DOI: 10.1016/j.ceca.2006.04.022] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2006] [Accepted: 04/25/2006] [Indexed: 11/20/2022]
Abstract
T-type Ca2+ channels play a number of different and pivotal roles in almost every type of neuronal oscillation expressed by thalamic neurones during non-rapid eye movement (NREM) sleep, including those underlying sleep theta waves, the K-complex and the slow (<1 Hz) sleep rhythm, sleep spindles and delta waves. In particular, the transient opening of T channels not only gives rise to the 'classical' low threshold Ca2+ potentials, and associated high frequency burst of action potentials, that are characteristically present during sleep spindles and delta waves, but also contributes to the high threshold bursts that underlie the thalamic generation of sleep theta rhythms. The persistent opening of a small fraction of T channels, i.e. I(Twindow), is responsible for the large amplitude and long lasting depolarization, or UP state, of the slow (<1 Hz) sleep oscillation in thalamic neurones. These cellular findings are in part matched by the wake-sleep phenotype of global and thalamic-selective CaV3.1 knockout mice that show a decreased amount of total NREM sleep time. T-type Ca2+ channels, therefore, constitute the single most crucial voltage-dependent conductance that permeates all activities of thalamic neurones during NREM sleep. Since I(Twindow) and high threshold bursts are not restricted to thalamic neurones, the cellular neurophysiology of T channels should now move away from the simplistic, though historically significant, view of these channels as being responsible only for low threshold Ca2+ potentials.
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Affiliation(s)
- Vincenzo Crunelli
- School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3US, UK.
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Blethyn KL, Hughes SW, Tóth TI, Cope DW, Crunelli V. Neuronal basis of the slow (<1 Hz) oscillation in neurons of the nucleus reticularis thalami in vitro. J Neurosci 2006; 26:2474-86. [PMID: 16510726 PMCID: PMC6793657 DOI: 10.1523/jneurosci.3607-05.2006] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During deep sleep and anesthesia, the EEG of humans and animals exhibits a distinctive slow (<1 Hz) rhythm. In inhibitory neurons of the nucleus reticularis thalami (NRT), this rhythm is reflected as a slow (<1 Hz) oscillation of the membrane potential comprising stereotypical, recurring "up" and "down" states. Here we show that reducing the leak current through the activation of group I metabotropic glutamate receptors (mGluRs) with either trans-ACPD [(+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid] (50-100 microM) or DHPG [(S)-3,5-dihydroxyphenylglycine] (100 microM) instates an intrinsic slow oscillation in NRT neurons in vitro that is qualitatively equivalent to that observed in vivo. A slow oscillation could also be evoked by synaptically activating mGluRs on NRT neurons via the tetanic stimulation of corticothalamic fibers. Through a combination of experiments and computational modeling we show that the up state of the slow oscillation is predominantly generated by the "window" component of the T-type Ca2+ current, with an additional supportive role for a Ca2+-activated nonselective cation current. The slow oscillation is also fundamentally reliant on an Ih current and is extensively shaped by both Ca2+- and Na+-activated K+ currents. In combination with previous work in thalamocortical neurons, this study suggests that the thalamus plays an important and active role in shaping the slow (<1 Hz) rhythm during deep sleep.
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Affiliation(s)
- Kate L Blethyn
- School of Biosciences, Cardiff University, Cardiff CF10 3US, United Kingdom
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Uchida G, Fukuda M, Tanifuji M. Correlated transition between two activity states of neurons. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:031910. [PMID: 16605561 DOI: 10.1103/physreve.73.031910] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Revised: 12/15/2005] [Indexed: 05/08/2023]
Abstract
In order to understand the dynamical properties of a neural network, it is important to characterize the relation between spike trains of two neurons in the network. In this study, we show that in some neuron pairs in inferior temporal cortices of macaque monkeys, spike trains of a pair are described by a two-dimensional Poisson process whose means are modulated by a common two-state Markov process. The common two-state Markov process describes a correlated state transition between firing and nonfiring states of the constituent neurons of the pair.
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Affiliation(s)
- Go Uchida
- Laboratory for Integrative Neural Systems, Brain Science Institute, The Institute of Physical and Chemical Research (RIKEN), Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan
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Kass JI, Mintz IM. Silent plateau potentials, rhythmic bursts, and pacemaker firing: three patterns of activity that coexist in quadristable subthalamic neurons. Proc Natl Acad Sci U S A 2005; 103:183-8. [PMID: 16373507 PMCID: PMC1324981 DOI: 10.1073/pnas.0506781102] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Subthalamic neurons display uncommon intrinsic behaviors that are likely to contribute to the motor and cognitive functions of the basal ganglia and to many of its disorders. Here, we report silent plateau potentials in these cells. These plateau responses start with a transient burst of action potentials that quickly diminish in amplitude because of spike inactivation and current shunt. The resulting interruption of spiking reveals a stable depolarization (up state) that clamps the cell membrane potential near -40 mV for several seconds. These plateau potentials coexist in single subthalamic neurons with more familiar patterns of burst and pacemaker firing. Within a narrow range of baseline membrane potentials (-67 to -60 mV), depolarization abruptly switches single cells from bistable to rhythmic bursts or tonic firing modes, thus selecting entirely distinct algorithms for integrating cortical and pallidal synaptic inputs.
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Affiliation(s)
- Jason I Kass
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Steriade M. Sleep, epilepsy and thalamic reticular inhibitory neurons. Trends Neurosci 2005; 28:317-24. [PMID: 15927688 DOI: 10.1016/j.tins.2005.03.007] [Citation(s) in RCA: 302] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Revised: 01/17/2005] [Accepted: 03/14/2005] [Indexed: 11/18/2022]
Abstract
Thalamic reticular neurons release the potent inhibitory neurotransmitter GABA and their main targets are thalamocortical neurons in the dorsal thalamus. This article focuses on two topics: (i) the role of thalamic reticular neurons in the initiation of spindles, a hallmark oscillation during early sleep stages; and (ii) the reticular-induced inhibition of thalamocortical neurons during cortically generated spike-wave seizures. Although hotly debated during the past decade, the idea of spindle generation by a network of GABAergic reticular neurons was recently supported by in vivo and in computo studies demonstrating interactions between inhibitory reticular neurons that lead to spindle sequences. During spike-wave seizures and electrical paroxysms of the Lennox-Gastaut type, which arise in the neocortex, reticular neurons are powerfully excited through corticofugal projections and they produce prolonged inhibitory postsynaptic potentials in thalamocortical neurons. Thus, GABAergic reticular neurons are crucial in the generation of some sleep rhythms, which produce synaptic plasticity, and in inhibiting external signals through thalamocortical neurons, which leads to unconsciousness during absence epilepsy.
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Affiliation(s)
- Mircea Steriade
- Laboratoire de Neurophysiologie, Faculté de Médecine, Université Laval, Québec, Canada G1K 7P4.
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