1
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Howard MA. New complex physiological findings evolve hypothesized mechanisms of Dravet syndrome. Neural Regen Res 2024; 19:1867-1868. [PMID: 38227502 DOI: 10.4103/1673-5374.390967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 11/09/2023] [Indexed: 01/17/2024] Open
Affiliation(s)
- MacKenzie A Howard
- Department of Neurology, Dell Medical School, Austin, TX, USA Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
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2
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Meneghetti N, Vannini E, Mazzoni A. Rodents' visual gamma as a biomarker of pathological neural conditions. J Physiol 2024; 602:1017-1048. [PMID: 38372352 DOI: 10.1113/jp283858] [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: 12/13/2022] [Accepted: 01/23/2024] [Indexed: 02/20/2024] Open
Abstract
Neural gamma oscillations (indicatively 30-100 Hz) are ubiquitous: they are associated with a broad range of functions in multiple cortical areas and across many animal species. Experimental and computational works established gamma rhythms as a global emergent property of neuronal networks generated by the balanced and coordinated interaction of excitation and inhibition. Coherently, gamma activity is strongly influenced by the alterations of synaptic dynamics which are often associated with pathological neural dysfunctions. We argue therefore that these oscillations are an optimal biomarker for probing the mechanism of cortical dysfunctions. Gamma oscillations are also highly sensitive to external stimuli in sensory cortices, especially the primary visual cortex (V1), where the stimulus dependence of gamma oscillations has been thoroughly investigated. Gamma manipulation by visual stimuli tuning is particularly easy in rodents, which have become a standard animal model for investigating the effects of network alterations on gamma oscillations. Overall, gamma in the rodents' visual cortex offers an accessible probe on dysfunctional information processing in pathological conditions. Beyond vision-related dysfunctions, alterations of gamma oscillations in rodents were indeed also reported in neural deficits such as migraine, epilepsy and neurodegenerative or neuropsychiatric conditions such as Alzheimer's, schizophrenia and autism spectrum disorders. Altogether, the connections between visual cortical gamma activity and physio-pathological conditions in rodent models underscore the potential of gamma oscillations as markers of neuronal (dys)functioning.
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Affiliation(s)
- Nicolò Meneghetti
- The Biorobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
- Department of Excellence for Robotics and AI, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Eleonora Vannini
- Neuroscience Institute, National Research Council (CNR), Pisa, Italy
| | - Alberto Mazzoni
- The Biorobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
- Department of Excellence for Robotics and AI, Scuola Superiore Sant'Anna, Pisa, Italy
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3
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Rusina E, Simonti M, Duprat F, Cestèle S, Mantegazza M. Voltage-gated sodium channels in genetic epilepsy: up and down of excitability. J Neurochem 2023. [PMID: 37654020 DOI: 10.1111/jnc.15947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 08/11/2023] [Accepted: 08/13/2023] [Indexed: 09/02/2023]
Abstract
The past two decades have witnessed a wide range of studies investigating genetic variants of voltage-gated sodium (NaV ) channels, which are involved in a broad spectrum of diseases, including several types of epilepsy. We have reviewed here phenotypes and pathological mechanisms of genetic epilepsies caused by variants in NaV α and β subunits, as well as of some relevant interacting proteins (FGF12/FHF1, PRRT2, and Ankyrin-G). Notably, variants of all these genes can induce either gain- or loss-of-function of NaV leading to either neuronal hyperexcitability or hypoexcitability. We present the results of functional studies obtained with different experimental models, highlighting that they should be interpreted considering the features of the experimental system used. These systems are models, but they have allowed us to better understand pathophysiological issues, ameliorate diagnostics, orientate genetic counseling, and select/develop therapies within a precision medicine framework. These studies have also allowed us to gain insights into the physiological roles of different NaV channels and of the cells that express them. Overall, our review shows the progress that has been made, but also the need for further studies on aspects that have not yet been clarified. Finally, we conclude by highlighting some significant themes of general interest that can be gleaned from the results of the work of the last two decades.
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Affiliation(s)
- Evgeniia Rusina
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
| | - Martina Simonti
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
| | - Fabrice Duprat
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
| | - Sandrine Cestèle
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
| | - Massimo Mantegazza
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
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4
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Goff KM, Liebergall SR, Jiang E, Somarowthu A, Goldberg EM. VIP interneuron impairment promotes in vivo circuit dysfunction and autism-related behaviors in Dravet syndrome. Cell Rep 2023; 42:112628. [PMID: 37310860 PMCID: PMC10592464 DOI: 10.1016/j.celrep.2023.112628] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 04/01/2023] [Accepted: 05/24/2023] [Indexed: 06/15/2023] Open
Abstract
Dravet syndrome (DS) is a severe neurodevelopmental disorder caused by loss-of-function variants in SCN1A, which encodes the voltage-gated sodium channel subunit Nav1.1. We recently showed that neocortical vasoactive intestinal peptide interneurons (VIP-INs) express Nav1.1 and are hypoexcitable in DS (Scn1a+/-) mice. Here, we investigate VIP-IN function at the circuit and behavioral level by performing in vivo 2-photon calcium imaging in awake wild-type (WT) and Scn1a+/- mice. VIP-IN and pyramidal neuron activation during behavioral transition from quiet wakefulness to active running is diminished in Scn1a+/- mice, and optogenetic activation of VIP-INs restores pyramidal neuron activity to WT levels during locomotion. VIP-IN selective Scn1a deletion reproduces core autism-spectrum-disorder-related behaviors in addition to cellular- and circuit-level deficits in VIP-IN function, but without epilepsy, sudden death, or avoidance behaviors seen in the global model. Hence, VIP-INs are impaired in vivo, which may underlie non-seizure cognitive and behavioral comorbidities in DS.
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Affiliation(s)
- Kevin M Goff
- Medical Scientist Training Program (MSTP), The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Neuroscience Graduate Group, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Sophie R Liebergall
- Medical Scientist Training Program (MSTP), The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Neuroscience Graduate Group, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Evan Jiang
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Ala Somarowthu
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Ethan M Goldberg
- Neuroscience Graduate Group, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Neurology, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
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5
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Berecki G, Bryson A, Polster T, Petrou S. Biophysical characterization and modelling of SCN1A gain-of-function predicts interneuron hyperexcitability and a predisposition to network instability through homeostatic plasticity. Neurobiol Dis 2023; 179:106059. [PMID: 36868483 DOI: 10.1016/j.nbd.2023.106059] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/11/2023] [Accepted: 02/27/2023] [Indexed: 03/05/2023] Open
Abstract
SCN1A gain-of-function variants are associated with early onset developmental and epileptic encephalopathies (DEEs) that possess distinct clinical features compared to Dravet syndrome caused by SCN1A loss-of-function. However, it is unclear how SCN1A gain-of-function may predispose to cortical hyper-excitability and seizures. Here, we first report the clinical features of a patient carrying a de novo SCN1A variant (T162I) associated with neonatal-onset DEE, and then characterize the biophysical properties of T162I and three other SCN1A variants associated with neonatal-onset DEE (I236V) and early infantile DEE (P1345S, R1636Q). In voltage clamp experiments, three variants (T162I, P1345S and R1636Q) exhibited changes in activation and inactivation properties that enhanced window current, consistent with gain-of-function. Dynamic action potential clamp experiments utilising model neurons incorporating Nav1.1. channels supported a gain-of-function mechanism for all four variants. Here, the T162I, I236V, P1345S, and R1636Q variants exhibited higher peak firing rates relative to wild type and the T162I and R1636Q variants produced a hyperpolarized threshold and reduced neuronal rheobase. To explore the impact of these variants upon cortical excitability, we used a spiking network model containing an excitatory pyramidal cell (PC) and parvalbumin positive (PV) interneuron population. SCN1A gain-of-function was modelled by enhancing the excitability of PV interneurons and then incorporating three simple forms of homeostatic plasticity that restored pyramidal cell firing rates. We found that homeostatic plasticity mechanisms exerted differential impact upon network function, with changes to PV-to-PC and PC-to-PC synaptic strength predisposing to network instability. Overall, our findings support a role for SCN1A gain-of-function and inhibitory interneuron hyperexcitability in early onset DEE. We propose a mechanism through which homeostatic plasticity pathways can predispose to pathological excitatory activity and contribute to phenotypic variability in SCN1A disorders.
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Affiliation(s)
- Géza Berecki
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC 3052, Australia.
| | - Alexander Bryson
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC 3052, Australia; Department of Neurology, Austin Health, Heidelberg, VIC 3084, Australia
| | - Tilman Polster
- Krankenhaus Mara, Bethel Epilepsy Centre, Department of Epileptology, Medical School, Bielefeld University, Campus Bielefeld-Bethel, Bielefeld, Germany
| | - Steven Petrou
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC 3052, Australia; Praxis Precision Medicines, Inc., Cambridge, MA 02142, USA; Department of the Florey Institute, University of Melbourne, Parkville, VIC 3050, Australia.
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6
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Quinn S, Brusel M, Ovadia M, Rubinstein M. Acute effect of antiseizure drugs on background oscillations in Scn1aA1783V Dravet syndrome mouse model. Front Pharmacol 2023; 14:1118216. [PMID: 37021051 PMCID: PMC10067575 DOI: 10.3389/fphar.2023.1118216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 03/07/2023] [Indexed: 03/22/2023] Open
Abstract
Dravet syndrome (Dravet) is a rare and severe form of developmental epileptic encephalopathy. Antiseizure medications (ASMs) for Dravet patients include valproic acid (VA) or clobazam (CLB), with or without stiripentol (STP), while sodium channel blockers like carbamazepine (CBZ) or lamotrigine (LTG) are contraindicated. In addition to their effect on epileptic phenotypes, ASMs were shown to modify the properties of background neuronal activity. Nevertheless, little is known about these background properties alterations in Dravet. Here, utilizing Dravet mice (DS, Scn1aA1783V/WT), we tested the acute effect of several ASMs on background electrocorticography (ECoG) activity and frequency of interictal spikes. Compared to wild-type mice, background ECoG activity in DS mice had lower power and reduced phase coherence, which was not corrected by any of the tested ASMs. However, acute administration of Dravet-recommended drugs, VA, CLB, or a combination of CLB + STP, caused, in most mice, a reduction in the frequency of interictal spikes, alongside an increase in the relative contribution of the beta frequency band. Conversely, CBZ and LTG increased the frequency of interictal spikes, with no effect on background spectral properties. Moreover, we uncovered a correlation between the reduction in interictal spike frequency, the drug-induced effect on the power of background activity, and a spectral shift toward higher frequency bands. Together, these data provide a comprehensive analysis of the effect of selected ASMs on the properties of background neuronal oscillations, and highlight a possible correlation between their effect on epilepsy and background activity.
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Affiliation(s)
- Shir Quinn
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Marina Brusel
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Mor Ovadia
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Moran Rubinstein
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- *Correspondence: Moran Rubinstein,
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7
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Bryson A, Petrou S. SCN1A channelopathies: Navigating from genotype to neural circuit dysfunction. Front Neurol 2023; 14:1173460. [PMID: 37139072 PMCID: PMC10149698 DOI: 10.3389/fneur.2023.1173460] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 03/28/2023] [Indexed: 05/05/2023] Open
Abstract
The SCN1A gene is strongly associated with epilepsy and plays a central role for supporting cortical excitation-inhibition balance through the expression of NaV1.1 within inhibitory interneurons. The phenotype of SCN1A disorders has been conceptualized as driven primarily by impaired interneuron function that predisposes to disinhibition and cortical hyperexcitability. However, recent studies have identified SCN1A gain-of-function variants associated with epilepsy, and the presence of cellular and synaptic changes in mouse models that point toward homeostatic adaptations and complex network remodeling. These findings highlight the need to understand microcircuit-scale dysfunction in SCN1A disorders to contextualize genetic and cellular disease mechanisms. Targeting the restoration of microcircuit properties may be a fruitful strategy for the development of novel therapies.
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Affiliation(s)
- Alexander Bryson
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
- *Correspondence: Alexander Bryson,
| | - Steven Petrou
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
- Praxis Precision Medicines, Inc., Cambridge, MA, United States
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Goisis RC, Chiavegato A, Gomez-Gonzalo M, Marcon I, Requie LM, Scholze P, Carmignoto G, Losi G. GABA tonic currents and glial cells are altered during epileptogenesis in a mouse model of Dravet syndrome. Front Cell Neurosci 2022; 16:919493. [PMID: 35936501 PMCID: PMC9350930 DOI: 10.3389/fncel.2022.919493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 06/28/2022] [Indexed: 11/17/2022] Open
Abstract
Dravet Syndrome (DS) is a rare autosomic encephalopathy with epilepsy linked to Nav1.1 channel mutations and defective GABAergic signaling. Effective therapies for this syndrome are lacking, urging a better comprehension of the mechanisms involved. In a recognized mouse model of DS, we studied GABA tonic current, a form of inhibition largely neglected in DS, in brain slices from developing mice before spontaneous seizures are reported. In neurons from the temporal cortex (TeCx) and CA1 region, GABA tonic current was reduced in DS mice compared to controls, while in the entorhinal cortex (ECx) it was not affected. In this region however allopregnanonole potentiation of GABA tonic current was reduced in DS mice, suggesting altered extrasynaptic GABAA subunits. Using THIP as a selective agonist, we found reduced δ subunit mediated tonic currents in ECx of DS mice. Unexpectedly in the dentate gyrus (DG), a region with high δ subunit expression, THIP-evoked currents in DS mice were larger than in controls. An immunofluorescence study confirmed that δ subunit expression was reduced in ECx and increased in DG of DS mice. Finally, considering the importance of neuroinflammation in epilepsy and neurodevelopmental disorders, we evaluated classical markers of glia activation. Our results show that DS mice have increased Iba1 reactivity and GFAP expression in both ECx and DG, compared to controls. Altogether we report that before spontaneous seizures, DS mice develop significant alterations of GABA tonic currents and glial cell activation. Understanding all the mechanisms involved in these alterations during disease maturation and progression may unveil new therapeutic targets.
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Affiliation(s)
- Rosa Chiara Goisis
- Department of Biomedical Science, University of Padua, Padua, Italy
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
| | - Angela Chiavegato
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
| | - Marta Gomez-Gonzalo
- Department of Biomedical Science, University of Padua, Padua, Italy
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
| | - Iacopo Marcon
- Department of Biomedical Science, University of Padua, Padua, Italy
| | | | - Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Giorgio Carmignoto
- Department of Biomedical Science, University of Padua, Padua, Italy
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
| | - Gabriele Losi
- Department of Biomedical Science, University of Padua, Padua, Italy
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
- *Correspondence: Gabriele Losi
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Chancey JH, Howard MA. Synaptic Integration in CA1 Pyramidal Neurons Is Intact despite Deficits in GABAergic Transmission in the Scn1a Haploinsufficiency Mouse Model of Dravet Syndrome. eNeuro 2022; 9:ENEURO.0080-22.2022. [PMID: 35523580 PMCID: PMC9116933 DOI: 10.1523/eneuro.0080-22.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/29/2022] [Accepted: 04/27/2022] [Indexed: 01/13/2023] Open
Abstract
Mutations of SCN1A, which encodes the voltage-gated sodium channel Nav1.1, can cause epilepsy disorders such as Dravet syndrome (DS) that are comorbid with wide-ranging neurologic dysfunction. Many studies suggest that Nav1.1 haploinsufficiency causes forebrain GABAergic interneuron hypoexcitability, while pyramidal neuron physiology is mostly unaltered, and that this serves as a primary cell physiology phenotype linking mutation to disease. We hypothesized that deficits in inhibition would alter synaptic integration during activation of the hippocampal microcircuit, thus disrupting cellular information processing and leading to seizures and cognitive deficits. We tested this hypothesis using ex vivo whole-cell recordings from CA1 pyramidal neurons in a heterozygous Scn1a knock-out mouse model and wild-type (WT) littermates, measuring responses to single and patterned synaptic stimulation and spontaneous synaptic activity. Overall, our experiments reveal a surprising normalcy of excitatory and inhibitory synaptic temporal integration in the hippocampus of Scn1a haploinsufficient mice. While miniature IPSCs and feedforward inhibition and were decreased, we did not identify a pattern or frequency of input that caused a failure of synaptic inhibition. We further show that reduced GABA release probability and subsequent reduced short-term depression may act to overcome deficits in inhibition normalizing input/output functions in the Scn1a haploinsufficient hippocampus. These experiments show that CA1 pyramidal neuron synaptic processing is surprisingly robust, even during decreased interneuron function, and more complex circuit activity is likely required to reveal altered function in the hippocampal microcircuit.
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Affiliation(s)
- Jessica Hotard Chancey
- Department of Neurology, Dell Medical School, Austin 78712, TX
- Department of Neuroscience and Center for Learning and Memory, University of Texas at Austin, Austin 78712, TX
| | - MacKenzie Allen Howard
- Department of Neurology, Dell Medical School, Austin 78712, TX
- Department of Neuroscience and Center for Learning and Memory, University of Texas at Austin, Austin 78712, TX
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Kaneko K, Currin CB, Goff KM, Wengert ER, Somarowthu A, Vogels TP, Goldberg EM. Developmentally regulated impairment of parvalbumin interneuron synaptic transmission in an experimental model of Dravet syndrome. Cell Rep 2022; 38:110580. [PMID: 35354025 PMCID: PMC9003081 DOI: 10.1016/j.celrep.2022.110580] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 01/09/2022] [Accepted: 03/06/2022] [Indexed: 11/25/2022] Open
Abstract
Dravet syndrome is a neurodevelopmental disorder characterized by epilepsy, intellectual disability, and sudden death due to pathogenic variants in SCN1A with loss of function of the sodium channel subunit Nav1.1. Nav1.1-expressing parvalbumin GABAergic interneurons (PV-INs) from young Scn1a+/− mice show impaired action potential generation. An approach assessing PV-IN function in the same mice at two time points shows impaired spike generation in all Scn1a+/− mice at postnatal days (P) 16–21, whether deceased prior or surviving to P35, with normalization by P35 in surviving mice. However, PV-IN synaptic transmission is dysfunctional in young Scn1a+/− mice that did not survive and in Scn1a+/− mice ≥ P35. Modeling confirms that PV-IN axonal propagation is more sensitive to decreased sodium conductance than spike generation. These results demonstrate dynamic dysfunction in Dravet syndrome: combined abnormalities of PV-IN spike generation and propagation drives early disease severity, while ongoing dysfunction of synaptic transmission contributes to chronic pathology. Dravet syndrome is caused by variants in SCN1A with loss of function of Nav1.1 sodium channels. Kaneko et al. use the “mini-slice” to record at two developmental time points. Impaired spike generation of Nav1.1-expressing PV interneurons in Scn1a+/− mice is transient, while abnormalities of PV interneuron synaptic transmission persist.
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Affiliation(s)
- Keisuke Kaneko
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, PA 19104, USA
| | - Christopher B Currin
- The Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg, Austria
| | - Kevin M Goff
- Medical Scientist Training Program (MSTP), The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Neuroscience Graduate Group, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Eric R Wengert
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, PA 19104, USA
| | - Ala Somarowthu
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, PA 19104, USA
| | - Tim P Vogels
- The Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg, Austria
| | - Ethan M Goldberg
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, PA 19104, USA; Neuroscience Graduate Group, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Neurology, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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11
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Almog Y, Mavashov A, Brusel M, Rubinstein M. Functional Investigation of a Neuronal Microcircuit in the CA1 Area of the Hippocampus Reveals Synaptic Dysfunction in Dravet Syndrome Mice. Front Mol Neurosci 2022; 15:823640. [PMID: 35370551 PMCID: PMC8966673 DOI: 10.3389/fnmol.2022.823640] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 02/21/2022] [Indexed: 02/05/2023] Open
Abstract
Dravet syndrome is severe childhood-onset epilepsy, caused by loss of function mutations in the SCN1A gene, encoding for the voltage-gated sodium channel NaV1.1. The leading hypothesis is that Dravet is caused by selective reduction in the excitability of inhibitory neurons, due to hampered activity of NaV1.1 channels in these cells. However, these initial neuronal changes can lead to further network alterations. Here, focusing on the CA1 microcircuit in hippocampal brain slices of Dravet syndrome (DS, Scn1aA1783V/WT) and wild-type (WT) mice, we examined the functional response to the application of Hm1a, a specific NaV1.1 activator, in CA1 stratum-oriens (SO) interneurons and CA1 pyramidal excitatory neurons. DS SO interneurons demonstrated reduced firing and depolarized threshold for action potential (AP), indicating impaired activity. Nevertheless, Hm1a induced a similar AP threshold hyperpolarization in WT and DS interneurons. Conversely, a smaller effect of Hm1a was observed in CA1 pyramidal neurons of DS mice. In these excitatory cells, Hm1a application resulted in WT-specific AP threshold hyperpolarization and increased firing probability, with no effect on DS neurons. Additionally, when the firing of SO interneurons was triggered by CA3 stimulation and relayed via activation of CA1 excitatory neurons, the firing probability was similar in WT and DS interneurons, also featuring a comparable increase in the firing probability following Hm1a application. Interestingly, a similar functional response to Hm1a was observed in a second DS mouse model, harboring the nonsense Scn1aR613X mutation. Furthermore, we show homeostatic synaptic alterations in both CA1 pyramidal neurons and SO interneurons, consistent with reduced excitation and inhibition onto CA1 pyramidal neurons and increased release probability in the CA1-SO synapse. Together, these results suggest global neuronal alterations within the CA1 microcircuit extending beyond the direct impact of NaV1.1 dysfunction.
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Affiliation(s)
- Yael Almog
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Anat Mavashov
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Marina Brusel
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Moran Rubinstein
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- *Correspondence: Moran Rubinstein,
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12
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Mattis J, Somarowthu A, Goff KM, Jiang E, Yom J, Sotuyo N, Mcgarry LM, Feng H, Kaneko K, Goldberg EM. Corticohippocampal circuit dysfunction in a mouse model of Dravet syndrome. eLife 2022; 11:e69293. [PMID: 35212623 PMCID: PMC8920506 DOI: 10.7554/elife.69293] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 02/24/2022] [Indexed: 11/13/2022] Open
Abstract
Dravet syndrome (DS) is a neurodevelopmental disorder due to pathogenic variants in SCN1A encoding the Nav1.1 sodium channel subunit, characterized by treatment-resistant epilepsy, temperature-sensitive seizures, developmental delay/intellectual disability with features of autism spectrum disorder, and increased risk of sudden death. Convergent data suggest hippocampal dentate gyrus (DG) pathology in DS (Scn1a+/-) mice. We performed two-photon calcium imaging in brain slice to uncover a profound dysfunction of filtering of perforant path input by DG in young adult Scn1a+/- mice. This was not due to dysfunction of DG parvalbumin inhibitory interneurons (PV-INs), which were only mildly impaired at this timepoint; however, we identified enhanced excitatory input to granule cells, suggesting that circuit dysfunction is due to excessive excitation rather than impaired inhibition. We confirmed that both optogenetic stimulation of entorhinal cortex and selective chemogenetic inhibition of DG PV-INs lowered seizure threshold in vivo in young adult Scn1a+/- mice. Optogenetic activation of PV-INs, on the other hand, normalized evoked responses in granule cells in vitro. These results establish the corticohippocampal circuit as a key locus of pathology in Scn1a+/- mice and suggest that PV-INs retain powerful inhibitory function and may be harnessed as a potential therapeutic approach toward seizure modulation.
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Affiliation(s)
- Joanna Mattis
- Department of Neurology, The Perelman School of Medicine at The University of PennsylvaniaPhiladelphiaUnited States
| | - Ala Somarowthu
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of PhiladelphiaPhiladelphiaUnited States
| | - Kevin M Goff
- Neuroscience Graduate Group, The University of Pennsylvania Perelman School of MedicinePhiladelphiaUnited States
| | - Evan Jiang
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of PhiladelphiaPhiladelphiaUnited States
| | - Jina Yom
- College of Arts and Sciences, The University of PennsylvaniaPhiladelphiaUnited States
| | - Nathaniel Sotuyo
- Neuroscience Graduate Group, The University of Pennsylvania Perelman School of MedicinePhiladelphiaUnited States
| | - Laura M Mcgarry
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of PhiladelphiaPhiladelphiaUnited States
| | - Huijie Feng
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of PhiladelphiaPhiladelphiaUnited States
| | - Keisuke Kaneko
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of PhiladelphiaPhiladelphiaUnited States
| | - Ethan M Goldberg
- Department of Neurology, The Perelman School of Medicine at The University of PennsylvaniaPhiladelphiaUnited States
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of PhiladelphiaPhiladelphiaUnited States
- Department of Neuroscience, The Perelman School of Medicine at The University of PennsylvaniaPhiladelphiaUnited States
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13
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Varani S, Vecchia D, Zucca S, Forli A, Fellin T. Stimulus Feature-Specific Control of Layer 2/3 Subthreshold Whisker Responses by Layer 4 in the Mouse Primary Somatosensory Cortex. Cereb Cortex 2021; 32:1419-1436. [PMID: 34448808 PMCID: PMC8971086 DOI: 10.1093/cercor/bhab297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 07/29/2021] [Accepted: 07/29/2021] [Indexed: 02/01/2023] Open
Abstract
In the barrel field of the rodent primary somatosensory cortex (S1bf), excitatory cells in layer 2/3 (L2/3) display sparse firing but reliable subthreshold response during whisker stimulation. Subthreshold responses encode specific features of the sensory stimulus, for example, the direction of whisker deflection. According to the canonical model for the flow of sensory information across cortical layers, activity in L2/3 is driven by layer 4 (L4). However, L2/3 cells receive excitatory inputs from other regions, raising the possibility that L4 partially drives L2/3 during whisker stimulation. To test this hypothesis, we combined patch-clamp recordings from L2/3 pyramidal neurons in S1bf with selective optogenetic inhibition of L4 during passive whisker stimulation in both anesthetized and awake head-restrained mice. We found that L4 optogenetic inhibition did not abolish the subthreshold whisker-evoked response nor it affected spontaneous membrane potential fluctuations of L2/3 neurons. However, L4 optogenetic inhibition decreased L2/3 subthreshold responses to whisker deflections in the preferred direction, and it increased L2/3 responses to stimuli in the nonpreferred direction, leading to a change in the direction tuning. Our results contribute to reveal the circuit mechanisms underlying the processing of sensory information in the rodent S1bf.
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Affiliation(s)
- Stefano Varani
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Dania Vecchia
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Stefano Zucca
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Angelo Forli
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy
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14
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Abstract
Genetic testing has yielded major advances in our understanding of the causes of epilepsy. Seizures remain resistant to treatment in a significant proportion of cases, particularly in severe, childhood-onset epilepsy, the patient population in which an underlying causative genetic variant is most likely to be identified. A genetic diagnosis can be explanatory as to etiology, and, in some cases, might suggest a therapeutic approach; yet, a clear path from genetic diagnosis to treatment remains unclear in most cases. Here, we discuss theoretical considerations behind the attempted use of small molecules for the treatment of genetic epilepsies, which is but one among various approaches currently under development. We explore a few salient examples and consider the future of the small molecule approach for genetic epilepsies. We conclude that significant additional work is required to understand how genetic variation leads to dysfunction of epilepsy-associated protein targets, and how this impacts the function of diverse subtypes of neurons embedded within distributed brain circuits to yield epilepsy and epilepsy-associated comorbidities. A syndrome- or even variant-specific approach may be required to achieve progress. Advances in the field will require improved methods for large-scale target validation, compound identification and optimization, and the development of accurate model systems that reflect the core features of human epilepsy syndromes, as well as novel approaches towards clinical trials of such compounds in small rare disease cohorts.
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Affiliation(s)
- Ethan M Goldberg
- Department of Pediatrics, Division of Neurology, Abramson Research Center, The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Abramson Research Center Room 502A, 19104, Philadelphia, PA, USA.
- Departments of Neurology and Neuroscience, The University of Pennsylvania Perelman School of Medicine, 19104, Philadelphia, PA, USA.
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15
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Forli A, Pisoni M, Printz Y, Yizhar O, Fellin T. Optogenetic strategies for high-efficiency all-optical interrogation using blue-light-sensitive opsins. eLife 2021; 10:63359. [PMID: 34032211 PMCID: PMC8177884 DOI: 10.7554/elife.63359] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 05/24/2021] [Indexed: 12/20/2022] Open
Abstract
All-optical methods for imaging and manipulating brain networks with high spatial resolution are fundamental to study how neuronal ensembles drive behavior. Stimulation of neuronal ensembles using two-photon holographic techniques requires high-sensitivity actuators to avoid photodamage and heating. Moreover, two-photon-excitable opsins should be insensitive to light at wavelengths used for imaging. To achieve this goal, we developed a novel soma-targeted variant of the large-conductance blue-light-sensitive opsin CoChR (stCoChR). In the mouse cortex in vivo, we combined holographic two-photon stimulation of stCoChR with an amplified laser tuned at the opsin absorption peak and two-photon imaging of the red-shifted indicator jRCaMP1a. Compared to previously characterized blue-light-sensitive soma-targeted opsins in vivo, stCoChR allowed neuronal stimulation with more than 10-fold lower average power and no spectral crosstalk. The combination of stCoChR, tuned amplified laser stimulation, and red-shifted functional indicators promises to be a powerful tool for large-scale interrogation of neural networks in the intact brain.
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Affiliation(s)
- Angelo Forli
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | - Matteo Pisoni
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy.,Università di Genova, Genova, Italy
| | - Yoav Printz
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Ofer Yizhar
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
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16
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Uchino K, Kawano H, Tanaka Y, Adaniya Y, Asahara A, Deshimaru M, Kubota K, Watanabe T, Katsurabayashi S, Iwasaki K, Hirose S. Inhibitory synaptic transmission is impaired at higher extracellular Ca 2+ concentrations in Scn1a +/- mouse model of Dravet syndrome. Sci Rep 2021; 11:10634. [PMID: 34017040 PMCID: PMC8137694 DOI: 10.1038/s41598-021-90224-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 05/07/2021] [Indexed: 12/17/2022] Open
Abstract
Dravet syndrome (DS) is an intractable form of childhood epilepsy that occurs in infancy. More than 80% of all patients have a heterozygous abnormality in the SCN1A gene, which encodes a subunit of Na+ channels in the brain. However, the detailed pathogenesis of DS remains unclear. This study investigated the synaptic pathogenesis of this disease in terms of excitatory/inhibitory balance using a mouse model of DS. We show that excitatory postsynaptic currents were similar between Scn1a knock-in neurons (Scn1a+/- neurons) and wild-type neurons, but inhibitory postsynaptic currents were significantly lower in Scn1a+/- neurons. Moreover, both the vesicular release probability and the number of inhibitory synapses were significantly lower in Scn1a+/- neurons compared with wild-type neurons. There was no proportional increase in inhibitory postsynaptic current amplitude in response to increased extracellular Ca2+ concentrations. Our study revealed that the number of inhibitory synapses is significantly reduced in Scn1a+/- neurons, while the sensitivity of inhibitory synapses to extracellular Ca2+ concentrations is markedly increased. These data suggest that Ca2+ tethering in inhibitory nerve terminals may be disturbed following the synaptic burst, likely leading to epileptic symptoms.
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Affiliation(s)
- Kouya Uchino
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Hiroyuki Kawano
- Research Institute for the Molecular Pathogeneses of Epilepsy, Fukuoka University, Fukuoka, Japan
| | - Yasuyoshi Tanaka
- Research Institute for the Molecular Pathogeneses of Epilepsy, Fukuoka University, Fukuoka, Japan
| | - Yuna Adaniya
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Ai Asahara
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Masanobu Deshimaru
- Research Institute for the Molecular Pathogeneses of Epilepsy, Fukuoka University, Fukuoka, Japan
| | - Kaori Kubota
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Takuya Watanabe
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Shutaro Katsurabayashi
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan.
- Research Institute for the Molecular Pathogeneses of Epilepsy, Fukuoka University, Fukuoka, Japan.
| | - Katsunori Iwasaki
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Shinichi Hirose
- Research Institute for the Molecular Pathogeneses of Epilepsy, Fukuoka University, Fukuoka, Japan
- Department of Pediatrics, School of Medicine, Fukuoka University, Fukuoka, Japan
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17
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Chen W, Luo B, Gao N, Li H, Wang H, Li L, Cui W, Zhang L, Sun D, Liu F, Dong Z, Ren X, Zhang H, Su H, Xiong WC, Mei L. Neddylation stabilizes Nav1.1 to maintain interneuron excitability and prevent seizures in murine epilepsy models. J Clin Invest 2021; 131:136956. [PMID: 33651714 DOI: 10.1172/jci136956] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 02/23/2021] [Indexed: 12/19/2022] Open
Abstract
The excitability of interneurons requires Nav1.1, the α subunit of the voltage-gated sodium channel. Nav1.1 deficiency and mutations reduce interneuron excitability, a major pathological mechanism for epilepsy syndromes. However, the regulatory mechanisms of Nav1.1 expression remain unclear. Here, we provide evidence that neddylation is critical to Nav1.1 stability. Mutant mice lacking Nae1, an obligatory component of the E1 ligase for neddylation, in parvalbumin-positive interneurons (PVINs) exhibited spontaneous epileptic seizures and premature death. Electrophysiological studies indicate that Nae1 deletion reduced PVIN excitability and GABA release and consequently increased the network excitability of pyramidal neurons (PyNs). Further analysis revealed a reduction in sodium-current density, not a change in channel property, in mutant PVINs and decreased Nav1.1 protein levels. These results suggest that insufficient neddylation in PVINs reduces Nav1.1 stability and thus the excitability of PVINs; the ensuing increased PyN activity causes seizures in mice. Consistently, Nav1.1 was found reduced by proteomic analysis that revealed abnormality in synapses and metabolic pathways. Our findings describe a role of neddylation in maintaining Nav1.1 stability for PVIN excitability and reveal what we believe is a new mechanism in the pathogenesis of epilepsy.
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Affiliation(s)
- Wenbing Chen
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Bin Luo
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Nannan Gao
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Haiwen Li
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Hongsheng Wang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Lei Li
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Wanpeng Cui
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Lei Zhang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Dong Sun
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Fang Liu
- Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Zhaoqi Dong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Xiao Ren
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Hongsheng Zhang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Huabo Su
- Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Wen-Cheng Xiong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.,Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, USA
| | - Lin Mei
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.,Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, USA
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18
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Goff KM, Goldberg EM. A Role for Vasoactive Intestinal Peptide Interneurons in Neurodevelopmental Disorders. Dev Neurosci 2021; 43:168-180. [PMID: 33794534 PMCID: PMC8440337 DOI: 10.1159/000515264] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/10/2021] [Indexed: 11/19/2022] Open
Abstract
GABAergic inhibitory interneurons of the cerebral cortex expressing vasoactive intestinal peptide (VIP-INs) are rapidly emerging as important regulators of network dynamics and normal circuit development. Several recent studies have also identified VIP-IN dysfunction in models of genetically determined neurodevelopmental disorders (NDDs). In this article, we review the known circuit functions of VIP-INs and how they may relate to accumulating evidence implicating VIP-INs in the mechanisms of prominent NDDs. We highlight recurring VIP-IN-mediated circuit motifs that are shared across cerebral cortical areas and how VIP-IN activity can shape sensory input, development, and behavior. Ultimately, we extract a set of themes that inform our understanding of how VIP-INs influence pathogenesis of NDDs. Using publicly available single-cell RNA sequencing data from the Allen Institute, we also identify several underexplored disease-associated genes that are highly expressed in VIP-INs. We survey these genes and their shared related disease phenotypes that may broadly implicate VIP-INs in autism spectrum disorder and intellectual disability rather than epileptic encephalopathy. Finally, we conclude with a discussion of the relevance of cell type-specific investigations and therapeutics in the age of genomic diagnosis and targeted therapeutics.
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Affiliation(s)
- Kevin M Goff
- Medical Scientist Training Program (MSTP), The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
- Neuroscience Graduate Group, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Ethan M Goldberg
- Neuroscience Graduate Group, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- The Epilepsy NeuroGenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Departments of Neurology, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
- Departments of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
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19
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Mantegazza M, Cestèle S, Catterall WA. Sodium channelopathies of skeletal muscle and brain. Physiol Rev 2021; 101:1633-1689. [PMID: 33769100 DOI: 10.1152/physrev.00025.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated sodium channels initiate action potentials in nerve, skeletal muscle, and other electrically excitable cells. Mutations in them cause a wide range of diseases. These channelopathy mutations affect every aspect of sodium channel function, including voltage sensing, voltage-dependent activation, ion conductance, fast and slow inactivation, and both biosynthesis and assembly. Mutations that cause different forms of periodic paralysis in skeletal muscle were discovered first and have provided a template for understanding structure, function, and pathophysiology at the molecular level. More recent work has revealed multiple sodium channelopathies in the brain. Here we review the well-characterized genetics and pathophysiology of the periodic paralyses of skeletal muscle and then use this information as a foundation for advancing our understanding of mutations in the structurally homologous α-subunits of brain sodium channels that cause epilepsy, migraine, autism, and related comorbidities. We include studies based on molecular and structural biology, cell biology and physiology, pharmacology, and mouse genetics. Our review reveals unexpected connections among these different types of sodium channelopathies.
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Affiliation(s)
- Massimo Mantegazza
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France.,INSERM, Valbonne-Sophia Antipolis, France
| | - Sandrine Cestèle
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France
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20
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Two-photon calcium imaging of seizures in awake, head-fixed mice. Cell Calcium 2021; 96:102380. [PMID: 33676317 DOI: 10.1016/j.ceca.2021.102380] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/10/2021] [Accepted: 02/16/2021] [Indexed: 11/23/2022]
Abstract
Epilepsy is a severe neurological disorder defined by spontaneous seizures. Current treatment options fail in a large proportion of patients, while questions as to the basic mechanisms of seizure initiation and propagation remain. Advances in imaging of seizures in experimental model systems could lead to a better understanding of mechanisms of seizures and epilepsy. Recent studies have used two-photon calcium imaging (2 P imaging) in awake, behaving mice in head-fixed preparations to image seizures in vivo at high speed and cellular-level resolution to identify key seizure-related cell classes. Here, we discuss such advances and present 2 P imaging data of excitatory neurons and defined subsets of cerebral cortex GABAergic inhibitory interneurons during naturalistic seizures in a mouse model of Dravet syndrome (Scn1a+/- mice) along with other behavioral measures. Results demonstrate differential recruitment of discrete interneuron subclasses, which could inform mechanisms of seizure generation and propagation in Dravet syndrome and other epilepsies.
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21
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Weston MC. The Heated Relationship Between Neural Activity and Seizures. Epilepsy Curr 2020; 21:62-63. [PMID: 34025277 PMCID: PMC7863303 DOI: 10.1177/1535759720976371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Interneuron Desynchronization Precedes Seizures in a Mouse Model of Dravet Syndrome Tran CH, Vaiana M, Nakuci J, et al. J Neurosci. 2020 Mar 25;40(13):2764-2775. doi: 10.1523/JNEUROSCI.2370-19.2020. Epub 2020 Feb 26. PMID: 32102923; PMCID: PMC7096149. Recurrent seizures, which define epilepsy, are transient abnormalities in the electrical activity of the brain. The mechanistic basis of seizure initiation, and the contribution of defined neuronal subtypes to seizure pathophysiology, remains poorly understood. We performed in vivo 2-photon calcium imaging in neocortex during temperature-induced seizures in male and female Dravet syndrome (Scn1a+/−) mice, a neurodevelopmental disorder with prominent temperature-sensitive epilepsy. Mean activity of both putative principal cells and parvalbumin-positive interneurons (PV-INs) was higher in Scn1a+/− relative to wild-type controls during quiet wakefulness at baseline and at elevated core body temperature. However, wild-type PV-INs showed a progressive synchronization in response to temperature elevation that was absent in PV-INs from Scn1a+/− mice. Hence, PV-IN activity remains intact interictally in Scn1a+/− mice, yet exhibits decreased synchrony immediately before seizure onset. We suggest that impaired PV-IN synchronization may contribute to the transition to the ictal state during temperature-induced seizures in Dravet syndrome.
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22
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Almog Y, Fadila S, Brusel M, Mavashov A, Anderson K, Rubinstein M. Developmental alterations in firing properties of hippocampal CA1 inhibitory and excitatory neurons in a mouse model of Dravet syndrome. Neurobiol Dis 2020; 148:105209. [PMID: 33271326 DOI: 10.1016/j.nbd.2020.105209] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 11/07/2020] [Accepted: 11/24/2020] [Indexed: 11/17/2022] Open
Abstract
Dravet syndrome (Dravet) is a rare, severe childhood-onset epilepsy, caused by heterozygous de novo mutations in the SCN1A gene, encoding for the alpha subunit of the voltage-gated sodium channel, NaV1.1. The neuronal basis of Dravet is debated, with evidence favoring reduced function of inhibitory neurons, that might be transient, or enhanced activity of excitatory cells. Here, we utilized Dravet mice to trace developmental changes in the hippocampal CA1 circuit, examining the properties of CA1 horizontal stratum-oriens (SO) interneurons and pyramidal neurons, through the pre-epileptic, severe and stabilization stages of Dravet. Our data indicate that reduced function of SO interneurons persists from the pre-epileptic through the stabilization stages, with the greatest functional impairment observed during the severe stage. In contrast, opposing changes were detected in CA1 excitatory neurons, with a transient increase in their excitability during the pre-epileptic stage, followed by reduced excitability at the severe stage. Interestingly, alterations in the function of both inhibitory and excitatory neurons were more pronounced when the firing was evoked by synaptic stimulation, implying that loss of function of NaV1.1 may also affect somatodendritic functions. These results suggest a complex pathophysiological mechanism and indicate that the developmental trajectory of this disease is governed by reciprocal functional changes in both excitatory and inhibitory neurons.
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Affiliation(s)
- Yael Almog
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; The Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Saja Fadila
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; The Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Marina Brusel
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Anat Mavashov
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Karen Anderson
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Moran Rubinstein
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; The Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel.
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23
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Impaired θ-γ Coupling Indicates Inhibitory Dysfunction and Seizure Risk in a Dravet Syndrome Mouse Model. J Neurosci 2020; 41:524-537. [PMID: 33234612 DOI: 10.1523/jneurosci.2132-20.2020] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/02/2020] [Accepted: 11/12/2020] [Indexed: 01/24/2023] Open
Abstract
Dravet syndrome (DS) is an epileptic encephalopathy that still lacks biomarkers for epileptogenesis and its treatment. Dysfunction of NaV1.1 sodium channels, which are chiefly expressed in inhibitory interneurons, explains the epileptic phenotype. Understanding the network effects of these cellular deficits may help predict epileptogenesis. Here, we studied θ-γ coupling as a potential marker for altered inhibitory functioning and epileptogenesis in a DS mouse model. We found that cortical θ-γ coupling was reduced in both male and female juvenile DS mice and persisted only if spontaneous seizures occurred. θ-γ Coupling was partly restored by cannabidiol (CBD). Locally disrupting NaV1.1 expression in the hippocampus or cortex yielded early attenuation of θ-γ coupling, which in the hippocampus associated with fast ripples, and which was replicated in a computational model when voltage-gated sodium currents were impaired in basket cells (BCs). Our results indicate attenuated θ-γ coupling as a promising early indicator of inhibitory dysfunction and seizure risk in DS.
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24
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Shore AN, Colombo S, Tobin WF, Petri S, Cullen ER, Dominguez S, Bostick CD, Beaumont MA, Williams D, Khodagholy D, Yang M, Lutz CM, Peng Y, Gelinas JN, Goldstein DB, Boland MJ, Frankel WN, Weston MC. Reduced GABAergic Neuron Excitability, Altered Synaptic Connectivity, and Seizures in a KCNT1 Gain-of-Function Mouse Model of Childhood Epilepsy. Cell Rep 2020; 33:108303. [PMID: 33113364 PMCID: PMC7712469 DOI: 10.1016/j.celrep.2020.108303] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 08/06/2020] [Accepted: 10/01/2020] [Indexed: 01/07/2023] Open
Abstract
Gain-of-function (GOF) variants in K+ channels cause severe childhood epilepsies, but there are no mechanisms to explain how increased K+ currents lead to network hyperexcitability. Here, we introduce a human Na+-activated K+ (KNa) channel variant (KCNT1-Y796H) into mice and, using a multiplatform approach, find motor cortex hyperexcitability and early-onset seizures, phenotypes strikingly similar to those of human patients. Although the variant increases KNa currents in cortical excitatory and inhibitory neurons, there is an increase in the KNa current across subthreshold voltages only in inhibitory neurons, particularly in those with non-fast-spiking properties, resulting in inhibitory-neuron-specific impairments in excitability and action potential (AP) generation. We further observe evidence of synaptic rewiring, including increases in homotypic synaptic connectivity, accompanied by network hyperexcitability and hypersynchronicity. These findings support inhibitory-neuron-specific mechanisms in mediating the epileptogenic effects of KCNT1 channel GOF, offering cell-type-specific currents and effects as promising targets for therapeutic intervention.
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Affiliation(s)
- Amy N Shore
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sophie Colombo
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - William F Tobin
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sabrina Petri
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Erin R Cullen
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Soledad Dominguez
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Michael A Beaumont
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Axion BioSystems, Atlanta, GA 30309, USA
| | - Damian Williams
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Dion Khodagholy
- Department of Electrical Engineering, Columbia University, New York, NY 10032, USA
| | - Mu Yang
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Yueqing Peng
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Jennifer N Gelinas
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Michael J Boland
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Wayne N Frankel
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Matthew C Weston
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA.
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25
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Lourenço J, Koukouli F, Bacci A. Synaptic inhibition in the neocortex: Orchestration and computation through canonical circuits and variations on the theme. Cortex 2020; 132:258-280. [PMID: 33007640 DOI: 10.1016/j.cortex.2020.08.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 07/28/2020] [Accepted: 08/31/2020] [Indexed: 12/15/2022]
Abstract
The neocortex plays a crucial role in all basic and abstract cognitive functions. Conscious mental processes are achieved through a correct flow of information within and across neocortical networks, whose particular activity state results from a tight balance between excitation and inhibition. The proper equilibrium between these indissoluble forces is operated with multiscale organization: along the dendro-somatic axis of single neurons and at the network level. Fast synaptic inhibition is assured by a multitude of inhibitory interneurons. During cortical activities, these cells operate a finely tuned division of labor that is epitomized by their detailed connectivity scheme. Recent results combining the use of mouse genetics, cutting-edge optical and neurophysiological approaches have highlighted the role of fast synaptic inhibition in driving cognition-related activity through a canonical cortical circuit, involving several major interneuron subtypes and principal neurons. Here we detail the organization of this cortical blueprint and we highlight the crucial role played by different neuron types in fundamental cortical computations. In addition, we argue that this canonical circuit is prone to many variations on the theme, depending on the resolution of the classification of neuronal types, and the cortical area investigated. Finally, we discuss how specific alterations of distinct inhibitory circuits can underlie several devastating brain diseases.
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Affiliation(s)
- Joana Lourenço
- Sorbonne Université, Institut Du Cerveau-Paris Brain Institute-ICM, Inserm U1127, CNRS UMR 7225, 47 Boulevard de L'Hôpital, 75013, Paris, France.
| | - Fani Koukouli
- Sorbonne Université, Institut Du Cerveau-Paris Brain Institute-ICM, Inserm U1127, CNRS UMR 7225, 47 Boulevard de L'Hôpital, 75013, Paris, France
| | - Alberto Bacci
- Sorbonne Université, Institut Du Cerveau-Paris Brain Institute-ICM, Inserm U1127, CNRS UMR 7225, 47 Boulevard de L'Hôpital, 75013, Paris, France.
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26
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Fadila S, Quinn S, Turchetti Maia A, Yakubovich D, Ovadia M, Anderson KL, Giladi M, Rubinstein M. Convulsive seizures and some behavioral comorbidities are uncoupled in the
Scn1a
A1783V
Dravet syndrome mouse model. Epilepsia 2020; 61:2289-2300. [DOI: 10.1111/epi.16662] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 07/30/2020] [Accepted: 07/30/2020] [Indexed: 02/03/2023]
Affiliation(s)
- Saja Fadila
- Goldschleger Eye Research Institute Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
- Department of Human Molecular Genetics and Biochemistry Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
| | - Shir Quinn
- Goldschleger Eye Research Institute Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
- Department of Human Molecular Genetics and Biochemistry Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
| | - Ana Turchetti Maia
- Goldschleger Eye Research Institute Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
| | - Daniel Yakubovich
- Department of Physiology and Pharmacology Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
- Schneider Children's Medical Center of Israel Petah Tikvah Israel
| | - Mor Ovadia
- Goldschleger Eye Research Institute Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
- Sagol School of Neuroscience Tel Aviv University Tel Aviv Israel
| | - Karen L. Anderson
- Goldschleger Eye Research Institute Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
| | - Moshe Giladi
- Department of Physiology and Pharmacology Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
| | - Moran Rubinstein
- Goldschleger Eye Research Institute Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
- Department of Human Molecular Genetics and Biochemistry Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
- Sagol School of Neuroscience Tel Aviv University Tel Aviv Israel
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27
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Guet-McCreight A, Skinner FK, Topolnik L. Common Principles in Functional Organization of VIP/Calretinin Cell-Driven Disinhibitory Circuits Across Cortical Areas. Front Neural Circuits 2020; 14:32. [PMID: 32581726 PMCID: PMC7296096 DOI: 10.3389/fncir.2020.00032] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/04/2020] [Indexed: 12/21/2022] Open
Abstract
In the brain, there is a vast diversity of different structures, circuitries, cell types, and cellular genetic expression profiles. While this large diversity can often occlude a clear understanding of how the brain works, careful analyses of analogous studies performed across different brain areas can hint at commonalities in neuronal organization. This in turn can yield a fundamental understanding of necessary circuitry components that are crucial for how information is processed across the brain. In this review, we outline recent in vivo and in vitro studies that have been performed in different cortical areas to characterize the vasoactive intestinal polypeptide (VIP)- and/or calretinin (CR)-expressing cells that specialize in inhibiting GABAergic interneurons. In doing so, we make the case that, across cortical structures, interneuron-specific cells commonly specialize in the synaptic disinhibition of excitatory neurons, which can ungate the integration and plasticity of external inputs onto excitatory neurons. In line with this, activation of interneuron- specific cells enhances animal performance across a variety of behavioral tasks that involve learning, memory formation, and sensory discrimination, and may represent a key target for therapeutic interventions under different pathological conditions. As such, interneuron-specific cells across different cortical structures are an essential network component for information processing and normal brain function.
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Affiliation(s)
- Alexandre Guet-McCreight
- Krembil Brain Institute - Division of Clinical and Computational Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Frances K Skinner
- Krembil Brain Institute - Division of Clinical and Computational Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Department of Medicine (Neurology), University of Toronto, Toronto, ON, Canada
| | - Lisa Topolnik
- Department of Biochemistry, Microbiology and Bio-informatics, Laval University, Québec, QC, Canada.,Neuroscience Axis, CHU de Québec Research Center (CHUL), Québec, QC, Canada
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28
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Vecchia D, Beltramo R, Vallone F, Chéreau R, Forli A, Molano-Mazón M, Bawa T, Binini N, Moretti C, Holtmaat A, Panzeri S, Fellin T. Temporal Sharpening of Sensory Responses by Layer V in the Mouse Primary Somatosensory Cortex. Curr Biol 2020; 30:1589-1599.e10. [PMID: 32169206 PMCID: PMC7198976 DOI: 10.1016/j.cub.2020.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 01/16/2020] [Accepted: 02/03/2020] [Indexed: 01/14/2023]
Abstract
The timing of stimulus-evoked spikes encodes information about sensory stimuli. Here we studied the neural circuits controlling this process in the mouse primary somatosensory cortex. We found that brief optogenetic activation of layer V pyramidal cells just after whisker deflection modulated the membrane potential of neurons and interrupted their long-latency whisker responses, increasing their accuracy in encoding whisker deflection time. In contrast, optogenetic inhibition of layer V during either passive whisker deflection or active whisking decreased accuracy in encoding stimulus or touch time, respectively. Suppression of layer V pyramidal cells increased reaction times in a texture discrimination task. Moreover, two-color optogenetic experiments revealed that cortical inhibition was efficiently recruited by layer V stimulation and that it mainly involved activation of parvalbumin-positive rather than somatostatin-positive interneurons. Layer V thus performs behaviorally relevant temporal sharpening of sensory responses through circuit-specific recruitment of cortical inhibition.
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Affiliation(s)
- Dania Vecchia
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, 16163 Genova and 38068 Rovereto, Italy
| | - Riccardo Beltramo
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Fabio Vallone
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, 16163 Genova and 38068 Rovereto, Italy
| | - Ronan Chéreau
- Department of Basic Neurosciences, Geneva University Neurocenter, Faculty of Medicine, University of Geneva, 1206 Geneva, Switzerland
| | - Angelo Forli
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, 16163 Genova and 38068 Rovereto, Italy
| | - Manuel Molano-Mazón
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, 16163 Genova and 38068 Rovereto, Italy; Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, 38068 Rovereto, Italy
| | - Tanika Bawa
- Department of Basic Neurosciences, Geneva University Neurocenter, Faculty of Medicine, University of Geneva, 1206 Geneva, Switzerland
| | - Noemi Binini
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, 16163 Genova and 38068 Rovereto, Italy
| | - Claudio Moretti
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, 16163 Genova and 38068 Rovereto, Italy
| | - Anthony Holtmaat
- Department of Basic Neurosciences, Geneva University Neurocenter, Faculty of Medicine, University of Geneva, 1206 Geneva, Switzerland
| | - Stefano Panzeri
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, 16163 Genova and 38068 Rovereto, Italy; Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, 38068 Rovereto, Italy
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, 16163 Genova and 38068 Rovereto, Italy.
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29
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Noebels JL. Predicting the impact of sodium channel mutations in human brain disease. Epilepsia 2020; 60 Suppl 3:S8-S16. [PMID: 31904123 PMCID: PMC6953257 DOI: 10.1111/epi.14724] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/15/2019] [Accepted: 03/18/2019] [Indexed: 12/21/2022]
Abstract
Genetic alteration of the sodium channel provides a remarkable opportunity to understand how epilepsy and its comorbidities arise from a molecular disease of excitable membranes, and a chance to create a better future for children with epileptic encephalopathy. In a single cell, the channel reliably acts as a voltage-sensitive switch, enabling axon impulse firing, whereas at a network level, it becomes a variable rheostat for regulating dynamic patterns of neuronal oscillations, including those underlying cognitive development, seizures, and even premature lethality. Despite steady progress linking genetic variation of the channels with distinctive clinical syndromes, our understanding of the intervening biologic complexity underlying each of them is only just beginning. More research on the functional contribution of individual channel subunits to specific brain networks and cellular plasticity in the developing brain is needed before we can reliably advance from precision diagnosis to precision treatment of inherited sodium channel disorders.
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Affiliation(s)
- Jeffrey L Noebels
- Blue Bird Circle Developmental Neurogenetics Laboratory, Departments of Neurology, Neuroscience, and Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
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30
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Mantegazza M, Broccoli V. SCN1A/Na V 1.1 channelopathies: Mechanisms in expression systems, animal models, and human iPSC models. Epilepsia 2020; 60 Suppl 3:S25-S38. [PMID: 31904127 DOI: 10.1111/epi.14700] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 03/04/2019] [Indexed: 12/20/2022]
Abstract
Pathogenic SCN1A/NaV 1.1 mutations cause well-defined epilepsies, including genetic epilepsy with febrile seizures plus (GEFS+) and the severe epileptic encephalopathy Dravet syndrome. In addition, they cause a severe form of migraine with aura, familial hemiplegic migraine. Moreover, SCN1A/NaV 1.1 variants have been inferred as risk factors in other types of epilepsy. We review here the advancements obtained studying pathologic mechanisms of SCN1A/NaV 1.1 mutations with experimental systems. We present results gained with in vitro expression systems, gene-targeted animal models, and the induced pluripotent stem cell (iPSC) technology, highlighting advantages, limits, and pitfalls for each of these systems. Overall, the results obtained in the last two decades confirm that the initial pathologic mechanism of epileptogenic SCN1A/NaV 1.1 mutations is loss-of-function of NaV 1.1 leading to hypoexcitability of at least some types of γ-aminobutyric acid (GABA)ergic neurons (including cortical and hippocampal parvalbumin-positive and somatostatin-positive ones). Conversely, more limited results point to NaV 1.1 gain-of-function for familial hemiplegic migraine (FHM) mutations. Behind these relatively simple pathologic mechanisms, an unexpected complexity has been observed, in part generated by technical issues in experimental studies and in part related to intrinsically complex pathophysiologic responses and remodeling, which yet remain to be fully disentangled.
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Affiliation(s)
- Massimo Mantegazza
- University Cote d'Azur (UCA), CNRS UMR7275, INSERM, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
| | - Vania Broccoli
- San Raffaele Scientific Institute, Milan, Italy.,Institute of Neuroscience, National Research Council (CNR), Milan, Italy
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31
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Interneuron Desynchronization Precedes Seizures in a Mouse Model of Dravet Syndrome. J Neurosci 2020; 40:2764-2775. [PMID: 32102923 DOI: 10.1523/jneurosci.2370-19.2020] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/27/2019] [Accepted: 02/13/2020] [Indexed: 12/14/2022] Open
Abstract
Recurrent seizures, which define epilepsy, are transient abnormalities in the electrical activity of the brain. The mechanistic basis of seizure initiation, and the contribution of defined neuronal subtypes to seizure pathophysiology, remains poorly understood. We performed in vivo two-photon calcium imaging in neocortex during temperature-induced seizures in male and female Dravet syndrome (Scn1a+/-) mice, a neurodevelopmental disorder with prominent temperature-sensitive epilepsy. Mean activity of both putative principal cells and parvalbumin-positive interneurons (PV-INs) was higher in Scn1a+/- relative to wild-type controls during quiet wakefulness at baseline and at elevated core body temperature. However, wild-type PV-INs showed a progressive synchronization in response to temperature elevation that was absent in PV-INs from Scn1a+/- mice. Hence, PV-IN activity remains intact interictally in Scn1a+/- mice, yet exhibits decreased synchrony immediately before seizure onset. We suggest that impaired PV-IN synchronization may contribute to the transition to the ictal state during temperature-induced seizures in Dravet syndrome.SIGNIFICANCE STATEMENT Epilepsy is a common neurological disorder defined by recurrent, unprovoked seizures. However, basic mechanisms of seizure initiation and propagation remain poorly understood. We performed in vivo two-photon calcium imaging in an experimental model of Dravet syndrome (Scn1a+/- mice)-a severe neurodevelopmental disorder defined by temperature-sensitive, treatment-resistant epilepsy-and record activity of putative excitatory neurons and parvalbumin-positive GABAergic neocortical interneurons (PV-INs) during naturalistic seizures induced by increased core body temperature. PV-IN activity was higher in Scn1a+/- relative to wild-type controls during quiet wakefulness. However, wild-type PV-INs showed progressive synchronization in response to temperature elevation that was absent in PV-INs from Scn1a+/- mice before seizure onset. Hence, impaired PV-IN synchronization may contribute to transition to seizure in Dravet syndrome.
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32
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Brondi M, Moroni M, Vecchia D, Molano-Mazón M, Panzeri S, Fellin T. High-Accuracy Detection of Neuronal Ensemble Activity in Two-Photon Functional Microscopy Using Smart Line Scanning. Cell Rep 2020; 30:2567-2580.e6. [PMID: 32101736 PMCID: PMC7043026 DOI: 10.1016/j.celrep.2020.01.105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 01/10/2020] [Accepted: 01/29/2020] [Indexed: 11/07/2022] Open
Abstract
Two-photon functional imaging using genetically encoded calcium indicators (GECIs) is one prominent tool to map neural activity. Under optimized experimental conditions, GECIs detect single action potentials in individual cells with high accuracy. However, using current approaches, these optimized conditions are never met when imaging large ensembles of neurons. Here, we developed a method that substantially increases the signal-to-noise ratio (SNR) of population imaging of GECIs by using galvanometric mirrors and fast smart line scan (SLS) trajectories. We validated our approach in anesthetized and awake mice on deep and dense GCaMP6 staining in the mouse barrel cortex during spontaneous and sensory-evoked activity. Compared to raster population imaging, SLS led to increased SNR, higher probability of detecting calcium events, and more precise identification of functional neuronal ensembles. SLS provides a cheap and easily implementable tool for high-accuracy population imaging of neural GCaMP6 signals by using galvanometric-based two-photon microscopes.
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Affiliation(s)
- Marco Brondi
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Monica Moroni
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy; Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy; Center for Mind and Brain Sciences (CIMeC), University of Trento, Trento, Italy
| | - Dania Vecchia
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Manuel Molano-Mazón
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy; Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Stefano Panzeri
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy; Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy.
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33
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Kuo SH, Louis ED, Faust PL, Handforth A, Chang SY, Avlar B, Lang EJ, Pan MK, Miterko LN, Brown AM, Sillitoe RV, Anderson CJ, Pulst SM, Gallagher MJ, Lyman KA, Chetkovich DM, Clark LN, Tio M, Tan EK, Elble RJ. Current Opinions and Consensus for Studying Tremor in Animal Models. CEREBELLUM (LONDON, ENGLAND) 2019; 18:1036-1063. [PMID: 31124049 PMCID: PMC6872927 DOI: 10.1007/s12311-019-01037-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Tremor is the most common movement disorder; however, we are just beginning to understand the brain circuitry that generates tremor. Various neuroimaging, neuropathological, and physiological studies in human tremor disorders have been performed to further our knowledge of tremor. But, the causal relationship between these observations and tremor is usually difficult to establish and detailed mechanisms are not sufficiently studied. To overcome these obstacles, animal models can provide an important means to look into human tremor disorders. In this manuscript, we will discuss the use of different species of animals (mice, rats, fruit flies, pigs, and monkeys) to model human tremor disorders. Several ways to manipulate the brain circuitry and physiology in these animal models (pharmacology, genetics, and lesioning) will also be discussed. Finally, we will discuss how these animal models can help us to gain knowledge of the pathophysiology of human tremor disorders, which could serve as a platform towards developing novel therapies for tremor.
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Affiliation(s)
- Sheng-Han Kuo
- Department of Neurology, Columbia University, 650 West 168th Street, Room 305, New York, NY, 10032, USA.
| | - Elan D Louis
- Department of Neurology, Yale School of Medicine, Yale University, 800 Howard Avenue, Ste Lower Level, New Haven, CT, 06519, USA.
- Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA.
- Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT, USA.
| | - Phyllis L Faust
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
| | - Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Su-Youne Chang
- Department of Neurologic Surgery and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Billur Avlar
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Eric J Lang
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Ming-Kai Pan
- Department of Medical Research and Neurology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Lauren N Miterko
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
| | - Amanda M Brown
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Roy V Sillitoe
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Collin J Anderson
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | | | - Kyle A Lyman
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | | | - Lorraine N Clark
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Murni Tio
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Eng-King Tan
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Rodger J Elble
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, IL, USA
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34
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Goff KM, Goldberg EM. Vasoactive intestinal peptide-expressing interneurons are impaired in a mouse model of Dravet syndrome. eLife 2019; 8:e46846. [PMID: 31282864 PMCID: PMC6629374 DOI: 10.7554/elife.46846] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/07/2019] [Indexed: 12/11/2022] Open
Abstract
Dravet Syndrome (DS) is a severe neurodevelopmental disorder caused by pathogenic loss of function variants in the gene SCN1A which encodes the voltage gated sodium (Na+) channel subunit Nav1.1. GABAergic interneurons expressing parvalbumin (PV-INs) and somatostatin (SST-INs) exhibit impaired excitability in DS (Scn1a+/-) mice. However, the function of a third major class of interneurons in DS - those expressing vasoactive intestinal peptide (VIP-IN) -is unknown. We recorded VIP-INs in brain slices from Scn1a+/-mice and wild-type littermate controls and found prominent impairment of irregular spiking (IS), but not continuous adapting (CA) VIP-INs, in Scn1a+/- mice. Application of the Nav1.1-specific toxin Hm1a rescued the observed deficits. The IS vs. CA firing pattern is determined by expression of KCNQ channels; IS VIP-INs switched to tonic firing with both pharmacologic blockade of M-current and muscarinic acetylcholine receptor activation. These results show that VIP-INs express Nav1.1 and are dysfunctional in DS, which may contribute to DS pathogenesis.
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Affiliation(s)
- Kevin M Goff
- Department of NeuroscienceThe University of Pennsylvania Perelman School of MedicinePhiladelphiaUnited States
- The Medical Scientist Training ProgramThe University of Pennsylvania Perelman School of MedicinePhiladelphiaUnited States
| | - Ethan M Goldberg
- Department of NeuroscienceThe University of Pennsylvania Perelman School of MedicinePhiladelphiaUnited States
- Division of Neurology, Department of PediatricsThe Children's Hospital of PhiladelphiaPhiladelphiaUnited States
- Department of NeurologyThe University of Pennsylvania Perelman School of MedicinePhiladelphiaUnited States
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Beck VC, Hull JM, Isom LL. Beyond Dravet Syndrome: Characterization of a Novel, More Severe SCN1A-Linked Epileptic Encephalopathy. Epilepsy Curr 2019; 19:266-268. [PMID: 31257984 PMCID: PMC6891832 DOI: 10.1177/1535759719858339] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
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Salgueiro-Pereira AR, Duprat F, Pousinha PA, Loucif A, Douchamps V, Regondi C, Ayrault M, Eugie M, Stunault MI, Escayg A, Goutagny R, Gnatkovsky V, Frassoni C, Marie H, Bethus I, Mantegazza M. A two-hit story: Seizures and genetic mutation interaction sets phenotype severity in SCN1A epilepsies. Neurobiol Dis 2019; 125:31-44. [DOI: 10.1016/j.nbd.2019.01.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/14/2018] [Accepted: 01/14/2019] [Indexed: 01/07/2023] Open
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Isom LL. Is Targeting of Compensatory Ion Channel Gene Expression a Viable Therapeutic Strategy for Dravet Syndrome? Epilepsy Curr 2019; 19:193-195. [PMID: 31035820 PMCID: PMC6610383 DOI: 10.1177/1535759719844780] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Augmented Reticular Thalamic Bursting and Seizures in Scn1a-Dravet Syndrome Ritter-Makinson S, Clemente-Perez A, Higashikubo B, Cho FS, Holden SS, Bennett E, Chkhaidze A, Eelkman Rooda OHJ, Cornet MC, Hoebeek FE, Yamakawa K, Cilio MR, Delord B, Paz JT. Cell Rep. 2019;26(1):54-64.e6. doi:10.1016/j.celrep.2018.12.018. Loss of function in the Scn1a gene leads to a severe epileptic encephalopathy called Dravet syndrome (DS). Reduced excitability in cortical inhibitory neurons is thought to be the major cause of DS seizures. Here, in contrast, we show enhanced excitability in thalamic inhibitory neurons that promotes the nonconvulsive seizures that are a prominent yet poorly understood feature of DS. In a mouse model of DS with a loss of function in Scn1a, reticular thalamic cells exhibited abnormally long bursts of firing caused by the downregulation of calcium-activated potassium SK channels. Our study supports a mechanism in which loss of SK activity causes the reticular thalamic neurons to become hyperexcitable and promote nonconvulsive seizures in DS. We propose that reduced excitability of inhibitory neurons is not global in DS and that non-GABAergic mechanisms such as SK channels may be important targets for treatment.
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Zucca S, Pasquale V, Lagomarsino de Leon Roig P, Panzeri S, Fellin T. Thalamic Drive of Cortical Parvalbumin-Positive Interneurons during Down States in Anesthetized Mice. Curr Biol 2019; 29:1481-1490.e6. [PMID: 31031117 PMCID: PMC6509281 DOI: 10.1016/j.cub.2019.04.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/08/2019] [Accepted: 04/03/2019] [Indexed: 11/26/2022]
Abstract
Up and down states are among the most prominent features of the thalamo-cortical system during non-rapid eye movement (NREM) sleep and many forms of anesthesia. Cortical interneurons, including parvalbumin (PV) cells, display firing activity during cortical down states, and this GABAergic signaling is associated with prolonged down-state durations. However, what drives PV interneurons to fire during down states remains unclear. We here tested the hypothesis that background thalamic activity may lead to suprathreshold activation of PV cells during down states. To this aim, we performed two-photon guided juxtasomal recordings from PV interneurons in the barrel field of the somatosensory cortex (S1bf) of anesthetized mice, while simultaneously collecting the local field potential (LFP) in S1bf and the multi-unit activity (MUA) in the ventral posteromedial (VPM) thalamic nucleus. We found that activity in the VPM was associated with longer down-state duration in S1bf and that down states displaying PV cell firing were associated with increased VPM activity. Moreover, thalamic inhibition through application of muscimol reduced the fraction of spikes discharged by PV cells during cortical down states. Finally, we inhibited PV interneurons using optogenetics during down states while monitoring cortical LFP under control conditions and after thalamic muscimol injection. We found increased latency of the optogenetically triggered down-to-up transitions upon thalamic pharmacological blockade compared to controls. These findings demonstrate that spontaneous thalamic activity inhibits cortex during down states through the activation of PV interneurons.
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Affiliation(s)
- Stefano Zucca
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Valentina Pasquale
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Pedro Lagomarsino de Leon Roig
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Stefano Panzeri
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems at UniTn, Istituto Italiano di Tecnologia, Corso Bettini 31, 38068 Rovereto, Italy
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
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A Transient Developmental Window of Fast-Spiking Interneuron Dysfunction in a Mouse Model of Dravet Syndrome. J Neurosci 2018; 38:7912-7927. [PMID: 30104343 DOI: 10.1523/jneurosci.0193-18.2018] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 07/12/2018] [Accepted: 07/17/2018] [Indexed: 01/06/2023] Open
Abstract
Dravet syndrome is a severe, childhood-onset epilepsy largely due to heterozygous loss-of-function mutation of the gene SCN1A, which encodes the type 1 neuronal voltage-gated sodium (Na+) channel α subunit Nav1.1. Prior studies in mouse models of Dravet syndrome (Scn1a+/- mice) indicate that, in cerebral cortex, Nav1.1 is predominantly expressed in GABAergic interneurons, in particular in parvalbumin-positive fast-spiking basket cell interneurons (PVINs). This has led to a model of Dravet syndrome pathogenesis in which Nav1.1 mutation leads to preferential dysfunction of interneurons, decreased synaptic inhibition, hyperexcitability, and epilepsy. However, such studies have been implemented at early developmental time points. Here, we performed electrophysiological recordings in acute brain slices prepared from male and female Scn1a+/- mice as well as age-matched wild-type littermate controls and found that, later in development, the excitability of PVINs had normalized. Analysis of action potential waveforms indirectly suggests a reorganization of axonal Na+ channels in PVINs from Scn1a+/- mice, a finding supported by immunohistochemical data showing elongation of the axon initial segment. Our results imply that transient impairment of action potential generation by PVINs may contribute to the initial appearance of epilepsy, but is not the mechanism of ongoing, chronic epilepsy in Dravet syndrome.SIGNIFICANCE STATEMENT Dravet syndrome is characterized by normal early development, temperature-sensitive seizures in infancy, progression to treatment-resistant epilepsy, developmental delay, autism, and sudden unexplained death due to mutation in SCN1A encoding the Na+ channel subunit Nav1.1. Prior work has revealed a preferential impact of Nav1.1 loss on the function of GABAergic inhibitory interneurons. However, such data derive exclusively from recordings of neurons in young Scn1a+/- mice. Here, we show that impaired action potential generation observed in parvalbumin-positive fast-spiking interneurons (PVINs) in Scn1a+/- mice during early development has normalized by postnatal day 35. This work suggests that a transient impairment of PVINs contributes to epilepsy onset, but is not the mechanism of ongoing, chronic epilepsy in Dravet syndrome.
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O’Leary T. Homeostasis, failure of homeostasis and degenerate ion channel regulation. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2018.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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41
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Forli A, Vecchia D, Binini N, Succol F, Bovetti S, Moretti C, Nespoli F, Mahn M, Baker CA, Bolton MM, Yizhar O, Fellin T. Two-Photon Bidirectional Control and Imaging of Neuronal Excitability with High Spatial Resolution In Vivo. Cell Rep 2018; 22:3087-3098. [PMID: 29539433 PMCID: PMC5863087 DOI: 10.1016/j.celrep.2018.02.063] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 12/22/2017] [Accepted: 02/14/2018] [Indexed: 12/01/2022] Open
Abstract
Sensory information is encoded within the brain in distributed spatiotemporal patterns of neuronal activity. Understanding how these patterns influence behavior requires a method to measure and to bidirectionally perturb with high spatial resolution the activity of the multiple neuronal cell types engaged in sensory processing. Here, we combined two-photon holography to stimulate neurons expressing blue light-sensitive opsins (ChR2 and GtACR2) with two-photon imaging of the red-shifted indicator jRCaMP1a in the mouse neocortex in vivo. We demonstrate efficient control of neural excitability across cell types and layers with holographic stimulation and improved spatial resolution by opsin somatic targeting. Moreover, we performed simultaneous two-photon imaging of jRCaMP1a and bidirectional two-photon manipulation of cellular activity with negligible effect of the imaging beam on opsin excitation. This all-optical approach represents a powerful tool to causally dissect how activity patterns in specified ensembles of neurons determine brain function and animal behavior.
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Affiliation(s)
- Angelo Forli
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova 16163, Italy
| | - Dania Vecchia
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova 16163, Italy
| | - Noemi Binini
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova 16163, Italy
| | - Francesca Succol
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova 16163, Italy
| | - Serena Bovetti
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova 16163, Italy
| | - Claudio Moretti
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova 16163, Italy
| | - Francesco Nespoli
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova 16163, Italy
| | - Mathias Mahn
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Christopher A Baker
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter 33458, FL, USA
| | - McLean M Bolton
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter 33458, FL, USA
| | - Ofer Yizhar
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova 16163, Italy.
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Abstract
The tragedy of epilepsy emerges from the combination of its high prevalence, impact upon sufferers and their families, and unpredictability. Childhood epilepsies are frequently severe, presenting in infancy with pharmaco-resistant seizures; are often accompanied by debilitating neuropsychiatric and systemic comorbidities; and carry a grave risk of mortality. Here, we review the most current basic science and translational research findings on several of the most catastrophic forms of pediatric epilepsy. We focus largely on genetic epilepsies and the research that is discovering the mechanisms linking disease genes to epilepsy syndromes. We also describe the strides made toward developing novel pharmacological and interventional treatment strategies to treat these disorders. The research reviewed provides hope for a complete understanding of, and eventual cure for, these childhood epilepsy syndromes.
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Affiliation(s)
- MacKenzie A Howard
- Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Texas, 78712;
| | - Scott C Baraban
- Epilepsy Research Laboratory in the Department of Neurological Surgery, Weill Institute for Neurosciences, University of California, San Francisco, California 94143;
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Opposing Phenotypes in Dravet Syndrome Patient-Derived Induced Pluripotent Stem Cell Neurons: Can Everyone Be Right? Epilepsy Curr 2017; 17:244-247. [PMID: 29225534 DOI: 10.5698/1535-7597.17.4.244] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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44
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Zucca S, D'Urso G, Pasquale V, Vecchia D, Pica G, Bovetti S, Moretti C, Varani S, Molano-Mazón M, Chiappalone M, Panzeri S, Fellin T. An inhibitory gate for state transition in cortex. eLife 2017; 6. [PMID: 28509666 PMCID: PMC5444901 DOI: 10.7554/elife.26177] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/15/2017] [Indexed: 01/23/2023] Open
Abstract
Large scale transitions between active (up) and silent (down) states during quiet wakefulness or NREM sleep regulate fundamental cortical functions and are known to involve both excitatory and inhibitory cells. However, if and how inhibition regulates these activity transitions is unclear. Using fluorescence-targeted electrophysiological recording and cell-specific optogenetic manipulation in both anesthetized and non-anesthetized mice, we found that two major classes of interneurons, the parvalbumin and the somatostatin positive cells, tightly control both up-to-down and down-to-up state transitions. Inhibitory regulation of state transition was observed under both natural and optogenetically-evoked conditions. Moreover, perturbative optogenetic experiments revealed that the inhibitory control of state transition was interneuron-type specific. Finally, local manipulation of small ensembles of interneurons affected cortical populations millimetres away from the modulated region. Together, these results demonstrate that inhibition potently gates transitions between cortical activity states, and reveal the cellular mechanisms by which local inhibitory microcircuits regulate state transitions at the mesoscale. DOI:http://dx.doi.org/10.7554/eLife.26177.001
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Affiliation(s)
- Stefano Zucca
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.,Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Giulia D'Urso
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.,Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Valentina Pasquale
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy
| | - Dania Vecchia
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.,Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Giuseppe Pica
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy.,Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Serena Bovetti
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.,Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Claudio Moretti
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.,Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Stefano Varani
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.,Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Manuel Molano-Mazón
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy.,Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Michela Chiappalone
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy
| | - Stefano Panzeri
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.,Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy.,Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.,Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
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Stern WM, Sander JW, Rothwell JC, Sisodiya SM. Impaired intracortical inhibition demonstrated in vivo in people with Dravet syndrome. Neurology 2017; 88:1659-1665. [PMID: 28356460 PMCID: PMC5405762 DOI: 10.1212/wnl.0000000000003868] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 01/30/2017] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Dravet syndrome is a rare neurodevelopmental disorder characterized by seizures and other neurologic problems. SCN1A mutations account for ∼80% of cases. Animal studies have implicated mutation-related dysregulated cortical inhibitory networks in its pathophysiology. We investigated such networks in people with the condition. METHODS Transcranial magnetic stimulation using single and paired pulse paradigms was applied to people with Dravet syndrome and to 2 control groups to study motor cortex excitability. RESULTS Short interval intracortical inhibition (SICI), which measures GABAergic inhibitory network behavior, was undetectable in Dravet syndrome, but detectable in all controls. Other paradigms, including those testing excitatory networks, showed no difference between Dravet and control groups. CONCLUSIONS There were marked differences in inhibitory networks, detected using SICI paradigms, while other inhibitory and excitatory paradigms yielded normal results. These human data showing reduced GABAergic inhibition in vivo in people with Dravet syndrome support established animal models.
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Affiliation(s)
- William M Stern
- From the Department of Clinical and Experimental Epilepsy, NIHR University College London Hospitals Biomedical Research Centre (W.M.S., J.W.S., S.M.S.), and Sobell Department of Motor Neuroscience and Movement Disorders (J.C.R.), UCL Institute of Neurology; Epilepsy Society (W.M.S., J.W.S., S.M.S.), Chalfont St Peter, UK; and Stichting Epilepsie Instellingen Nederland (SEIN) (J.W.S.), Heemstede, the Netherlands
| | - Josemir W Sander
- From the Department of Clinical and Experimental Epilepsy, NIHR University College London Hospitals Biomedical Research Centre (W.M.S., J.W.S., S.M.S.), and Sobell Department of Motor Neuroscience and Movement Disorders (J.C.R.), UCL Institute of Neurology; Epilepsy Society (W.M.S., J.W.S., S.M.S.), Chalfont St Peter, UK; and Stichting Epilepsie Instellingen Nederland (SEIN) (J.W.S.), Heemstede, the Netherlands
| | - John C Rothwell
- From the Department of Clinical and Experimental Epilepsy, NIHR University College London Hospitals Biomedical Research Centre (W.M.S., J.W.S., S.M.S.), and Sobell Department of Motor Neuroscience and Movement Disorders (J.C.R.), UCL Institute of Neurology; Epilepsy Society (W.M.S., J.W.S., S.M.S.), Chalfont St Peter, UK; and Stichting Epilepsie Instellingen Nederland (SEIN) (J.W.S.), Heemstede, the Netherlands
| | - Sanjay M Sisodiya
- From the Department of Clinical and Experimental Epilepsy, NIHR University College London Hospitals Biomedical Research Centre (W.M.S., J.W.S., S.M.S.), and Sobell Department of Motor Neuroscience and Movement Disorders (J.C.R.), UCL Institute of Neurology; Epilepsy Society (W.M.S., J.W.S., S.M.S.), Chalfont St Peter, UK; and Stichting Epilepsie Instellingen Nederland (SEIN) (J.W.S.), Heemstede, the Netherlands.
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Dutton SBB, Dutt K, Papale LA, Helmers S, Goldin AL, Escayg A. Early-life febrile seizures worsen adult phenotypes in Scn1a mutants. Exp Neurol 2017; 293:159-171. [PMID: 28373025 DOI: 10.1016/j.expneurol.2017.03.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 02/17/2017] [Accepted: 03/22/2017] [Indexed: 01/27/2023]
Abstract
Mutations in the voltage-gated sodium channel (VGSC) gene SCN1A, encoding the Nav1.1 channel, are responsible for a number of epilepsy disorders including genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome (DS). Patients with SCN1A mutations often experience prolonged early-life febrile seizures (FSs), raising the possibility that these events may influence epileptogenesis and lead to more severe adult phenotypes. To test this hypothesis, we subjected 21-23-day-old mice expressing the human SCN1A GEFS+ mutation R1648H to prolonged hyperthermia, and then examined seizure and behavioral phenotypes during adulthood. We found that early-life FSs resulted in lower latencies to induced seizures, increased severity of spontaneous seizures, hyperactivity, and impairments in social behavior and recognition memory during adulthood. Biophysical analysis of brain slice preparations revealed an increase in epileptiform activity in CA3 pyramidal neurons along with increased action potential firing, providing a mechanistic basis for the observed worsening of adult phenotypes. These findings demonstrate the long-term negative impact of early-life FSs on disease outcomes. This has important implications for the clinical management of this patient population and highlights the need for therapeutic interventions that could ameliorate disease progression.
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Affiliation(s)
- Stacey B B Dutton
- Department of Human Genetics, Emory University, Atlanta, GA 30022, USA; Department of Biology, Agnes Scott College, Atlanta, GA 30030, USA
| | - Karoni Dutt
- Departments of Microbiology & Molecular Genetics and Anatomy & Neurobiology, University of California, Irvine, CA 92697, USA
| | - Ligia A Papale
- Department of Human Genetics, Emory University, Atlanta, GA 30022, USA
| | - Sandra Helmers
- Department of Neurology, Emory University, Atlanta, GA 30022, USA
| | - Alan L Goldin
- Departments of Microbiology & Molecular Genetics and Anatomy & Neurobiology, University of California, Irvine, CA 92697, USA
| | - Andrew Escayg
- Department of Human Genetics, Emory University, Atlanta, GA 30022, USA.
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Balestrini S, Sisodiya SM. Pharmacogenomics in epilepsy. Neurosci Lett 2017; 667:27-39. [PMID: 28082152 PMCID: PMC5846849 DOI: 10.1016/j.neulet.2017.01.014] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 12/12/2022]
Abstract
Genetic variation can influence response to antiepileptic drug (AED) treatment through various effector processes. Metabolism of many AEDs is mediated by the cytochrome P450 (CYP) family; some of the CYPs have allelic variants that may affect serum AED concentrations. ‘Precision medicine’ focuses on the identification of an underlying genetic aetiology allowing personalised therapeutic choices. Certain human leukocyte antigen, HLA, alleles are associated with an increased risk of idiosyncratic adverse drug reactions. New results are emerging from large-scale multinational efforts, likely imminently to add knowledge of value from a pharmacogenetic perspective.
There is high variability in the response to antiepileptic treatment across people with epilepsy. Genetic factors significantly contribute to such variability. Recent advances in the genetics and neurobiology of the epilepsies are establishing the basis for a new era in the treatment of epilepsy, focused on each individual and their specific epilepsy. Variation in response to antiepileptic drug treatment may arise from genetic variation in a range of gene categories, including genes affecting drug pharmacokinetics, and drug pharmacodynamics, but also genes held to actually cause the epilepsy itself. From a purely pharmacogenetic perspective, there are few robust genetic findings with established evidence in epilepsy. Many findings are still controversial with anecdotal or less secure evidence and need further validation, e.g. variation in genes for transporter systems and antiepileptic drug targets. The increasing use of genetic sequencing and the results of large-scale collaborative projects may soon expand the established evidence. Precision medicine treatments represent a growing area of interest, focussing on reversing or circumventing the pathophysiological effects of specific gene mutations. This could lead to a dramatic improvement of the effectiveness and safety of epilepsy treatments, by targeting the biological mechanisms responsible for epilepsy in each specific individual. Whilst much has been written about epilepsy pharmacogenetics, there does now seem to be building momentum that promises to deliver results of use in clinic.
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Affiliation(s)
- Simona Balestrini
- NIHR University College London Hospitals Biomedical Research Centre, Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, and Epilepsy Society, Chalfont-St-Peter, Bucks, United Kingdom; Neuroscience Department, Polytechnic University of Marche, Ancona, Italy
| | - Sanjay M Sisodiya
- NIHR University College London Hospitals Biomedical Research Centre, Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, and Epilepsy Society, Chalfont-St-Peter, Bucks, United Kingdom.
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Abstract
The epileptic encephalopathies are severe and often treatment-resistant conditions that are associated with a progressive disturbance of brain function, resulting in a broad range of neurological and non-neurological comorbidities. The concept of epileptic encephalopathies entails that the encephalopathy aspect of the overall condition is primarily driven by the epileptic activity of the disease, which often manifests as specific and pathological features on the electroencephalogram. Genetic factors in epileptic encephalopathies are increasingly recognized. As of 2016, more than 30 genes have been securely implicated as causative genes for genetic epileptic encephalopathies. Even though the traditional concept of epileptic encephalopathies entails that the progressive disturbance of brain dysfunction is primarily due to the abnormal hypersynchronous activity that underlies the seizure disorders, this strict concept rarely holds true for patients with identified genetic etiologies. More commonly, an underlying genetic etiology is thought to predispose both to the neurodevelopmental comorbidities and to the seizure phenotype with a complex interaction between both. In this chapter, we will elucidate to what extent neurodegeneration rather than epilepsy-related regression is a feature of the common epileptic encephalopathies, drawing parallels between two relatively separate fields of neurogenetic research.
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