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Kleis P, Paschen E, Häussler U, Haas CA. Low frequency stimulation for seizure suppression: Identification of optimal targets in the entorhinal-hippocampal circuit. Brain Stimul 2024; 17:395-404. [PMID: 38531502 DOI: 10.1016/j.brs.2024.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/15/2024] [Accepted: 03/22/2024] [Indexed: 03/28/2024] Open
Abstract
BACKGROUND Mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis (HS) is a common form of drug-resistant focal epilepsy in adults. Treatment for pharmacoresistant patients remains a challenge, with deep brain stimulation (DBS) showing promise for alleviating intractable seizures. This study explores the efficacy of low frequency stimulation (LFS) on specific neuronal targets within the entorhinal-hippocampal circuit in a mouse model of MTLE. OBJECTIVE Our previous research demonstrated that LFS of the medial perforant path (MPP) fibers in the sclerotic hippocampus reduced seizures in epileptic mice. Here, we aimed to identify the critical neuronal population responsible for this antiepileptic effect by optogenetically stimulating presynaptic and postsynaptic compartments of the MPP-dentate granule cell (DGC) synapse at 1 Hz. We hypothesize that specific targets for LFS can differentially influence seizure activity depending on the cellular identity and location within or outside the seizure focus. METHODS We utilized the intrahippocampal kainate (ihKA) mouse model of MTLE and targeted specific neural populations using optogenetic stimulation. We recorded intracranial neuronal activity from freely moving chronically epileptic mice with and without optogenetic LFS up to 3 h. RESULTS We found that LFS of MPP fibers in the sclerotic hippocampus effectively suppressed epileptiform activity while stimulating principal cells in the MEC had no impact. Targeting DGCs in the sclerotic septal or non-sclerotic temporal hippocampus with LFS did not reduce seizure numbers but shortened the epileptiform bursts. CONCLUSION Presynaptic stimulation of the MPP-DGC synapse within the sclerotic hippocampus is critical for seizure suppression via LFS.
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Affiliation(s)
- Piret Kleis
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Enya Paschen
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany.
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Wenzel M, Huberfeld G, Grayden DB, de Curtis M, Trevelyan AJ. A debate on the neuronal origin of focal seizures. Epilepsia 2023; 64 Suppl 3:S37-S48. [PMID: 37183507 DOI: 10.1111/epi.17650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/26/2023] [Accepted: 05/12/2023] [Indexed: 05/16/2023]
Abstract
A critical question regarding how focal seizures start is whether we can identify particular cell classes that drive the pathological process. This was the topic for debate at the recent International Conference for Technology and Analysis of Seizures (ICTALS) meeting (July 2022, Bern, CH) that we summarize here. The debate has been fueled in recent times by the introduction of powerful new ways to manipulate subpopulations of cells in relative isolation, mostly using optogenetics. The motivation for resolving the debate is to identify novel targets for therapeutic interventions through a deeper understanding of the etiology of seizures.
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Affiliation(s)
- Michael Wenzel
- Department of Epileptology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Gilles Huberfeld
- Neurology Department, Hopital Fondation Adolphe de Rothschild, Paris, France
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, Université PSL, Paris, France
| | - David B Grayden
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, St Vincent's Hospital, The University of Melbourne, Melbourne, Victoria, Australia
- Graeme Clark Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Marco de Curtis
- Epilepsy Unit, Fondazione I.R.C.C.S., Istituto Neurologico Carlo Besta, Milan, Italy
| | - Andrew J Trevelyan
- Newcastle University Biosciences Institute, Medical School, Framlington Place, Newcastle upon Tyne, UK
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Schoeters R, Tarnaud T, Weyn L, Joseph W, Raedt R, Tanghe E. Quantitative analysis of the optogenetic excitability of CA1 neurons. Front Comput Neurosci 2023; 17:1229715. [PMID: 37649730 PMCID: PMC10465168 DOI: 10.3389/fncom.2023.1229715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 07/27/2023] [Indexed: 09/01/2023] Open
Abstract
Introduction Optogenetics has emerged as a promising technique for modulating neuronal activity and holds potential for the treatment of neurological disorders such as temporal lobe epilepsy (TLE). However, clinical translation still faces many challenges. This in-silico study aims to enhance the understanding of optogenetic excitability in CA1 cells and to identify strategies for improving stimulation protocols. Methods Employing state-of-the-art computational models coupled with Monte Carlo simulated light propagation, the optogenetic excitability of four CA1 cells, two pyramidal and two interneurons, expressing ChR2(H134R) is investigated. Results and discussion The results demonstrate that confining the opsin to specific neuronal membrane compartments significantly improves excitability. An improvement is also achieved by focusing the light beam on the most excitable cell region. Moreover, the perpendicular orientation of the optical fiber relative to the somato-dendritic axis yields superior results. Inter-cell variability is observed, highlighting the importance of considering neuron degeneracy when designing optogenetic tools. Opsin confinement to the basal dendrites of the pyramidal cells renders the neuron the most excitable. A global sensitivity analysis identified opsin location and expression level as having the greatest impact on simulation outcomes. The error reduction of simulation outcome due to coupling of neuron modeling with light propagation is shown. The results promote spatial confinement and increased opsin expression levels as important improvement strategies. On the other hand, uncertainties in these parameters limit precise determination of the irradiance thresholds. This study provides valuable insights on optogenetic excitability of CA1 cells useful for the development of improved optogenetic stimulation protocols for, for instance, TLE treatment.
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Affiliation(s)
- Ruben Schoeters
- WAVES, Department of Information Technology (INTEC), Ghent University/IMEC, Ghent, Belgium
- 4BRAIN, Department of Neurology, Institute for Neuroscience, Ghent University, Ghent, Belgium
| | - Thomas Tarnaud
- WAVES, Department of Information Technology (INTEC), Ghent University/IMEC, Ghent, Belgium
| | - Laila Weyn
- WAVES, Department of Information Technology (INTEC), Ghent University/IMEC, Ghent, Belgium
- 4BRAIN, Department of Neurology, Institute for Neuroscience, Ghent University, Ghent, Belgium
| | - Wout Joseph
- WAVES, Department of Information Technology (INTEC), Ghent University/IMEC, Ghent, Belgium
| | - Robrecht Raedt
- 4BRAIN, Department of Neurology, Institute for Neuroscience, Ghent University, Ghent, Belgium
| | - Emmeric Tanghe
- WAVES, Department of Information Technology (INTEC), Ghent University/IMEC, Ghent, Belgium
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Graham RT, Parrish RR, Alberio L, Johnson EL, Owens L, Trevelyan AJ. Optogenetic stimulation reveals a latent tipping point in cortical networks during ictogenesis. Brain 2023; 146:2814-2827. [PMID: 36572952 PMCID: PMC10316782 DOI: 10.1093/brain/awac487] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 11/17/2022] [Accepted: 12/06/2022] [Indexed: 12/28/2022] Open
Abstract
Brain-state transitions are readily apparent from changes in brain rhythms,1 but are difficult to predict, suggestive that the underlying cause is latent to passive recording methods. Among the most important transitions, clinically, are the starts of seizures. We here show that an 'active probing' approach may have several important benefits for epileptic management, including by helping predict these transitions. We used mice expressing the optogenetic actuator, channelrhodopsin, in pyramidal cells, allowing this population to be stimulated in isolation. Intermittent stimulation at frequencies as low as 0.033 Hz (period = 30 s) delayed the onset of seizure-like events in an acute brain slice model of ictogenesis, but the effect was lost if stimulation was delivered at even lower frequencies (1/min). Notably, active probing additionally provides advance indication of when seizure-like activity is imminent, revealed by monitoring the postsynaptic response to stimulation. The postsynaptic response, recorded extracellularly, showed an all-or-nothing change in both amplitude and duration, a few hundred seconds before seizure-like activity began-a sufficient length of time to provide a helpful warning of an impending seizure. The change in the postsynaptic response then persisted for the remainder of the recording, indicative of a state change from a pre-epileptic to a pro-epileptic network. This occurred in parallel with a large increase in the stimulation-triggered Ca2+ entry into pyramidal dendrites, and a step increase in the number of evoked postsynaptic action potentials, both consistent with a reduction in the threshold for dendritic action potentials. In 0 Mg2+ bathing media, the reduced threshold was not associated with changes in glutamatergic synaptic function, nor of GABAergic release from either parvalbumin or somatostatin interneurons, but simulations indicate that the step change in the optogenetic response can instead arise from incremental increases in intracellular [Cl-]. The change in the response to stimulation was replicated by artificially raising intracellular [Cl-], using the optogenetic chloride pump, halorhodopsin. By contrast, increases in extracellular [K+] cannot account for the firing patterns in the response to stimulation, although this, and other cellular changes, may contribute to ictal initiation in other circumstances. We describe how these various cellular changes form a synergistic network of positive feedback mechanisms, which may explain the precipitous nature of seizure onset. This model of seizure initiation draws together several major lines of epilepsy research as well as providing an important proof-of-principle regarding the utility of open-loop brain stimulation for clinical management of the condition.
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Affiliation(s)
- Robert T Graham
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - R Ryley Parrish
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Laura Alberio
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Emily L Johnson
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Laura Owens
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Andrew J Trevelyan
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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Zaaimi B, Turnbull M, Hazra A, Wang Y, Gandara C, McLeod F, McDermott EE, Escobedo-Cousin E, Idil AS, Bailey RG, Tardio S, Patel A, Ponon N, Gausden J, Walsh D, Hutchings F, Kaiser M, Cunningham MO, Clowry GJ, LeBeau FEN, Constandinou TG, Baker SN, Donaldson N, Degenaar P, O'Neill A, Trevelyan AJ, Jackson A. Closed-loop optogenetic control of the dynamics of neural activity in non-human primates. Nat Biomed Eng 2023; 7:559-575. [PMID: 36266536 PMCID: PMC7614485 DOI: 10.1038/s41551-022-00945-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 08/14/2022] [Indexed: 11/08/2022]
Abstract
Electrical neurostimulation is effective in the treatment of neurological disorders, but associated recording artefacts generally limit its applications to open-loop stimuli. Real-time and continuous closed-loop control of brain activity can, however, be achieved by pairing concurrent electrical recordings and optogenetics. Here we show that closed-loop optogenetic stimulation with excitatory opsins enables the precise manipulation of neural dynamics in brain slices from transgenic mice and in anaesthetized non-human primates. The approach generates oscillations in quiescent tissue, enhances or suppresses endogenous patterns in active tissue and modulates seizure-like bursts elicited by the convulsant 4-aminopyridine. A nonlinear model of the phase-dependent effects of optical stimulation reproduced the modulation of cycles of local-field potentials associated with seizure oscillations, as evidenced by the systematic changes in the variability and entropy of the phase-space trajectories of seizures, which correlated with changes in their duration and intensity. We also show that closed-loop optogenetic neurostimulation could be delivered using intracortical optrodes incorporating light-emitting diodes. Closed-loop optogenetic approaches may be translatable to therapeutic applications in humans.
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Affiliation(s)
- B Zaaimi
- Biosciences Institute, Newcastle University, Newcastle, UK
- School of Life and Health Sciences, Aston University, Birmingham, UK
| | - M Turnbull
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - A Hazra
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Y Wang
- School of Computing, Newcastle University, Newcastle, UK
| | - C Gandara
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - F McLeod
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - E E McDermott
- Biosciences Institute, Newcastle University, Newcastle, UK
| | | | - A Shah Idil
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - R G Bailey
- School of Engineering, Newcastle University, Newcastle, UK
| | - S Tardio
- School of Engineering, Newcastle University, Newcastle, UK
| | - A Patel
- School of Engineering, Newcastle University, Newcastle, UK
| | - N Ponon
- School of Engineering, Newcastle University, Newcastle, UK
| | - J Gausden
- School of Engineering, Newcastle University, Newcastle, UK
| | - D Walsh
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - F Hutchings
- School of Computing, Newcastle University, Newcastle, UK
| | - M Kaiser
- School of Computing, Newcastle University, Newcastle, UK
- NIHR, Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Nottingham, UK
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, UK
- Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - M O Cunningham
- School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - G J Clowry
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - F E N LeBeau
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - T G Constandinou
- Department of Electrical and Electronic Engineering, Imperial College, London, UK
| | - S N Baker
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - N Donaldson
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - P Degenaar
- School of Engineering, Newcastle University, Newcastle, UK
| | - A O'Neill
- School of Engineering, Newcastle University, Newcastle, UK
| | - A J Trevelyan
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - A Jackson
- Biosciences Institute, Newcastle University, Newcastle, UK.
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Stieve BJ, Smith MM, Krook-Magnuson E. LINCs Are Vulnerable to Epileptic Insult and Fail to Provide Seizure Control via On-Demand Activation. eNeuro 2023; 10:ENEURO.0195-22.2022. [PMID: 36725340 PMCID: PMC9933934 DOI: 10.1523/eneuro.0195-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 12/13/2022] [Accepted: 12/19/2022] [Indexed: 02/03/2023] Open
Abstract
Temporal lobe epilepsy (TLE) is notoriously pharmacoresistant, and identifying novel therapeutic targets for controlling seizures is crucial. Long-range inhibitory neuronal nitric oxide synthase-expressing cells (LINCs), a population of hippocampal neurons, were recently identified as a unique source of widespread inhibition in CA1, able to elicit both GABAA-mediated and GABAB-mediated postsynaptic inhibition. We therefore hypothesized that LINCs could be an effective target for seizure control. LINCs were optogenetically activated for on-demand seizure intervention in the intrahippocampal kainate (KA) mouse model of chronic TLE. Unexpectedly, LINC activation at 1 month post-KA did not substantially reduce seizure duration in either male or female mice. We tested two different sets of stimulation parameters, both previously found to be effective with on-demand optogenetic approaches, but neither was successful. Quantification of LINCs following intervention revealed a substantial reduction of LINC numbers compared with saline-injected controls. We also observed a decreased number of LINCs when the site of initial insult (i.e., KA injection) was moved to the amygdala [basolateral amygdala (BLA)-KA], and correspondingly, no effect of light delivery on BLA-KA seizures. This indicates that LINCs may be a vulnerable population in TLE, regardless of the site of initial insult. To determine whether long-term circuitry changes could influence outcomes, we continued testing once a month for up to 6 months post-KA. However, at no time point did LINC activation provide meaningful seizure suppression. Altogether, our results suggest that LINCs are not a promising target for seizure inhibition in TLE.
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Affiliation(s)
- Bethany J Stieve
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
| | - Madison M Smith
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
| | - Esther Krook-Magnuson
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
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7
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Wickham J, Ledri M, Andersson M, Kokaia M. Cell-specific switch for epileptiform activity: critical role of interneurons in the mouse subicular network. Cereb Cortex 2023; 33:6171-6183. [PMID: 36611229 PMCID: PMC10183737 DOI: 10.1093/cercor/bhac493] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/17/2022] [Accepted: 11/18/2022] [Indexed: 01/09/2023] Open
Abstract
During epileptic seizures, neuronal network activity is hyper synchronized whereby GABAergic parvalbumin-interneurons may have a key role. Previous studies have mostly utilized 4-aminopyridine to induce epileptiform discharges in brain slices from healthy animals. However, it is not clear if the seizure-triggering ability of parvalbumin-interneurons also holds true without the use of external convulsive agents. Here, we investigate whether synchronized activation of parvalbumin-interneurons or principal cells can elicit epileptiform discharges in subiculum slices of epileptic mice. We found that selective synchronized activation of parvalbumin-interneurons or principal cells with optogenetics do not result in light-induced epileptiform discharges (LIEDs) neither in epileptic nor in normal brain slices. Adding 4-aminopyridine to slices, activation of parvalbumin-interneurons still failed to trigger LIEDs. In contrast, such activation of principal neurons readily generated LIEDs with features resembling afterdischarges. When GABAA receptor blocker was added to the perfusion medium, the LIEDs were abolished. These results demonstrate that in subiculum, selective synchronized activation of principal excitatory neurons can trigger epileptiform discharges by recruiting a large pool of downstream interneurons. This study also suggests region-specific role of principal neurons and interneurons in ictogenesis, opening towards differential targeting of specific brain areas for future treatment strategies tailored for individual patients with epilepsy.
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Affiliation(s)
- J Wickham
- Epilepsy Center, Department of Clinical Sciences, Lund University, Sölvegatan 17, 223 62 Lund, Sweden
| | - M Ledri
- Epilepsy Center, Department of Clinical Sciences, Lund University, Sölvegatan 17, 223 62 Lund, Sweden
| | - M Andersson
- Epilepsy Center, Department of Clinical Sciences, Lund University, Sölvegatan 17, 223 62 Lund, Sweden
| | - M Kokaia
- Epilepsy Center, Department of Clinical Sciences, Lund University, Sölvegatan 17, 223 62 Lund, Sweden
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Proskurina EY, Chizhov AV, Zaitsev AV. Optogenetic Low-Frequency Stimulation of Principal Neurons, but Not Parvalbumin-Positive Interneurons, Prevents Generation of Ictal Discharges in Rodent Entorhinal Cortex in an In Vitro 4-Aminopyridine Model. Int J Mol Sci 2022; 24:ijms24010195. [PMID: 36613660 PMCID: PMC9820186 DOI: 10.3390/ijms24010195] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/17/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
Low-frequency electrical stimulation is used to treat some drug-resistant forms of epilepsy. Despite the effectiveness of the method in suppressing seizures, there is a considerable risk of side effects. An optogenetic approach allows the targeting of specific populations of neurons, which can increase the effectiveness and safety of low-frequency stimulation. In our study, we tested the efficacy of the suppression of ictal activity in entorhinal cortex slices in a 4-aminopyridine model with three variants of low-frequency light stimulation (LFLS): (1) activation of excitatory and inhibitory neurons (on Thy1-ChR2-YFP mice), (2) activation of inhibitory interneurons only (on PV-Cre mice after virus injection with channelrhodopsin2 gene), and (3) hyperpolarization of excitatory neurons (on Wistar rats after virus injection with archaerhodopsin gene). Only in the first variant did simultaneous LFLS of excitatory and inhibitory neurons replace ictal activity with interictal activity. We suggest that LFLS caused changes in the concentration gradients of K+ and Na+ cations across the neuron membrane, which activated Na-K pumping. According to the mathematical modeling, the increase in Na-K pump activity in neurons induced by LFLS led to an antiepileptic effect. Thus, a less specific and generalized optogenetic effect on entorhinal cortex neurons was more effective in suppressing ictal activity in the 4-aminopyridine model.
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Affiliation(s)
- Elena Y. Proskurina
- Almazov National Medical Research Centre, 2 Akkuratova Street, 197341 St. Petersburg, Russia
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Toreza Prospekt, 194223 St. Petersburg, Russia
| | - Anton V. Chizhov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Toreza Prospekt, 194223 St. Petersburg, Russia
- Computational Physics Laboratory, Ioffe Institute, 26 Polytekhnicheskaya Street, 194021 St. Petersburg, Russia
- MathNeuro Team, Inria Centre at Universite Cote d’Azur, 06902 Sophia Antipolis, France
| | - Aleksey V. Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Toreza Prospekt, 194223 St. Petersburg, Russia
- Correspondence:
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Acharya AR, Larsen LE, Delbeke J, Wadman WJ, Vonck K, Meurs A, Boon P, Raedt R. In vivo inhibition of epileptiform afterdischarges in rat hippocampus by light-activated chloride channel, stGtACR2. CNS Neurosci Ther 2022; 29:907-916. [PMID: 36482869 PMCID: PMC9928558 DOI: 10.1111/cns.14029] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 10/31/2022] [Accepted: 11/01/2022] [Indexed: 12/13/2022] Open
Abstract
AIMS The blue light-sensitive chloride-conducting opsin, stGtACR2, provides potent optogenetic silencing of neurons. The present study investigated whether activation of stGtACR2 in granule cells of the dentate gyrus (DG) inhibits epileptic afterdischarges in a rat model. METHODS Rats were bilaterally injected with 0.9 μl of AAV2/7-CaMKIIα-stGtACR2-fusionred in the DG. Three weeks later, afterdischarges were recorded from the DG by placing an optrode at the injection site and a stimulation electrode in the perforant path (PP). Afterdischarges were evoked every 10 min by unilateral electrical stimulation of the PP (20 Hz, 10 s). During every other afterdischarge, the DG was illuminated for 5 or 30 s, first ipsilaterally and then bilaterally to the PP stimulation. The line length metric of the afterdischarges was compared between illumination conditions. RESULTS Ipsilateral stGtACR2 activation during afterdischarges decreased the local field potential line length only during illumination and specifically at the illuminated site but did not reduce afterdischarge duration. Bilateral illumination did not terminate the afterdischarges. CONCLUSION Optogenetic inhibition of excitatory neurons using the blue-light sensitive chloride channel stGtACR2 reduced the amplitude of electrically induced afterdischarges in the DG at the site of illumination, but this local inhibitory effect was insufficient to reduce the duration of the afterdischarge.
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Affiliation(s)
- Anirudh R. Acharya
- 4BRAIN Team, Department of Head and Skin, Faculty of Medicine and Health SciencesGhent UniversityGhentBelgium
| | - Lars Emil Larsen
- 4BRAIN Team, Department of Head and Skin, Faculty of Medicine and Health SciencesGhent UniversityGhentBelgium
| | - Jean Delbeke
- 4BRAIN Team, Department of Head and Skin, Faculty of Medicine and Health SciencesGhent UniversityGhentBelgium
| | - Wytse J. Wadman
- 4BRAIN Team, Department of Head and Skin, Faculty of Medicine and Health SciencesGhent UniversityGhentBelgium
| | - Kristl Vonck
- 4BRAIN Team, Department of Head and Skin, Faculty of Medicine and Health SciencesGhent UniversityGhentBelgium
| | - Alfred Meurs
- 4BRAIN Team, Department of Head and Skin, Faculty of Medicine and Health SciencesGhent UniversityGhentBelgium
| | - Paul Boon
- 4BRAIN Team, Department of Head and Skin, Faculty of Medicine and Health SciencesGhent UniversityGhentBelgium
| | - Robrecht Raedt
- 4BRAIN Team, Department of Head and Skin, Faculty of Medicine and Health SciencesGhent UniversityGhentBelgium
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Li J, Feng P, Zhao L, Chen J, Du M, Song J, Wu Y. Transition behavior of the seizure dynamics modulated by the astrocyte inositol triphosphate noise. CHAOS (WOODBURY, N.Y.) 2022; 32:113121. [PMID: 36456345 DOI: 10.1063/5.0124123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Accepted: 10/17/2022] [Indexed: 06/17/2023]
Abstract
Epilepsy is a neurological disorder with recurrent seizures, which convey complex dynamical characteristics including chaos and randomness. Until now, the underlying mechanism has not been fully elucidated, especially the bistable property beneath the epileptic random induction phenomena in certain conditions. Inspired by the recent finding that astrocyte GTPase-activating protein (G-protein)-coupled receptors could be involved in stochastic epileptic seizures, we proposed a neuron-astrocyte network model, incorporating the noise of the astrocytic second messenger, inositol triphosphate (IP3) that is modulated by G-protein-coupled receptor activation. Based on this model, we have statistically analyzed the transitions of epileptic seizures by performing repeatable simulation trials. Our simulation results show that the increase in the IP3 noise intensity induces depolarization-block epileptic seizures together with an increase in neuronal firing frequency, consistent with corresponding experiments. Meanwhile, the bistable states of the seizure dynamics were present under certain noise intensities, during which the neuronal firing pattern switches between regular sparse spiking and epileptic seizure states. This random presence of epileptic seizures is absent when the noise intensity continues to increase, accompanying with an increase in the epileptic depolarization block duration. The simulation results also shed light on the fact that calcium signals in astrocytes play significant roles in the pattern formations of the epileptic seizure. Our results provide a potential pathway for understanding the epileptic randomness in certain conditions.
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Affiliation(s)
- Jiajia Li
- College of Information and Control Engineering, Xi'an University of Architecture and Technology, Shaanxi, Xi'an 710055, China
| | - Peihua Feng
- State Key Laboratory for Strength and Vibration of Mechanical Structures, National Demonstration Center for Experimental Mechanics Education, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Liang Zhao
- College of Information and Control Engineering, Xi'an University of Architecture and Technology, Shaanxi, Xi'an 710055, China
| | - Junying Chen
- College of Information and Control Engineering, Xi'an University of Architecture and Technology, Shaanxi, Xi'an 710055, China
| | - Mengmeng Du
- School of Mathematics and Data Science, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Jian Song
- Department of Neurosurgery, Wuhan General Hospital of PLA, Wuhan 430070, China
| | - Ying Wu
- State Key Laboratory for Strength and Vibration of Mechanical Structures, National Demonstration Center for Experimental Mechanics Education, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
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11
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Intracranial Monitoring to Verify Novel Transcranial Electric Stimulation in an Epileptic Swine Model. ELECTRONICS 2022. [DOI: 10.3390/electronics11142195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Invasive deep brain stimulation has proven to be clinically therapeutic for patients with drug-refractory epilepsy. The aim of this study was to develop a novel transcranial electrical device as a noninvasive stimulation modality for seizure treatment. We fabricated a novel transcranial electrical device and tested it in four swine brains with depth electrodes surgically implanted under neuro-navigation. Stimulation with two high-frequency alternating currents was used to cause an interference envelope. Acute focal epilepsy was induced by a subcortical injection of penicillin and specific anesthesia protocol. The frequency and electric field of the stimulation in the hippocampus were investigated. The two frequencies (2 k and 2.14 kHz) of stimulation successfully caused an envelope of 140 Hz. With 1 mA stimulation, the electric field degraded gradually and induced an in situ electric field of 0.68 mV/mm in the hippocampi. The interference mode transcranial electric stimulation attenuated the originally induced epileptic form discharges. No neuronal or axonal injuries were noted histopathologically after the stimulation. The feasibility and biosafety of our proposed device were preliminarily verified. Future translational research should focus on the electrode deposition and stimulation parameters for a quantitative therapeutic effect.
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12
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Proskurina EY, Zaitsev AV. Photostimulation activates fast-spiking interneurons and pyramidal cells in the entorhinal cortex of Thy1-ChR2-YFP line 18 mice. Biochem Biophys Res Commun 2021; 580:87-92. [PMID: 34627001 DOI: 10.1016/j.bbrc.2021.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/01/2021] [Indexed: 10/20/2022]
Abstract
The application of optogenetics in animals has provided new insights into both fundamental neuroscience and diseases of the nervous system. This is primarily due to the fact that optogenetics allows selectively activating or inhibiting particular types of neurons. One of the first transgenic mouse lines developed for the optogenetic experiment was Thy1-ChR2-YFP. Thy1 is an immunoglobulin superfamily member expressing in projection neurons, so it was assumed that channelrhodopsin-2 (ChR2) would be primarily expressed in projection neurons. However, the specificity of ChR2 expression under promoter Thy1 in different lines has to be clarified yet. Therefore, we aimed to determine the cell specificity of ChR2 expression in the entorhinal cortex of Thy1-ChR2-YFP line 18 mice. We have found that both pyramidal cells and fast-spiking interneurons in deep layers of the entorhinal cortex depolarized and fired in response to 470-nm photostimulation. To exclude the effect of synaptic activation of interneurons by pyramidal cells, we used a selective antagonist of AMPA receptors. Under these conditions, inhibitory postsynaptic currents decreased but did not disappear completely. Furthermore, gabazine inhibited these postsynaptic currents entirely, thus confirming the direct activation of interneurons by light. These data demonstrate that ChR2 is expressed in both pyramidal neurons and fast-spiking interneurons of the entorhinal cortex in Thy1-ChR2-YFP mice.
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Affiliation(s)
- Elena Y Proskurina
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, 44, Toreza Prospekt, St. Petersburg, 194223, Russia; Almazov National Medical Research Centre, Institute of Experimental Medicine, 2 Akkuratova Street, St. Petersburg, 197341, Russia.
| | - Aleksey V Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, 44, Toreza Prospekt, St. Petersburg, 194223, Russia.
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13
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Xu C, Gong Y, Wang Y, Chen Z. New advances in pharmacoresistant epilepsy towards precise management-from prognosis to treatments. Pharmacol Ther 2021; 233:108026. [PMID: 34718071 DOI: 10.1016/j.pharmthera.2021.108026] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/15/2021] [Accepted: 10/25/2021] [Indexed: 12/13/2022]
Abstract
Epilepsy, one of the most severe neurological diseases, is characterized by abrupt recurrent seizures. Despite great progress in the development of antiseizure drugs (ASDs) based on diverse molecular targets, more than one third of epilepsy patients still show resistance to ASDs, a condition termed pharmacoresistant epilepsy. The management of pharmacoresistant epilepsy involves serious challenges. In the past decade, promising advances have been made in the use of interdisciplinary techniques involving biophysics, bioinformatics, biomaterials and biochemistry, which allow more precise prognosis and development of drug target for pharmacoresistant epilepsy. Notably, novel experimental tools such as viral vector gene delivery, optogenetics and chemogenetics have provided a framework for promising approaches to the precise treatment of pharmacoresistant epilepsy. In this review, historical achievements especially recent advances of the past decade in the prognosis and treatment of pharmacoresistant epilepsy from both clinical and laboratory settings are presented and summarized. We propose that the further development of novel experimental tools at cellular or molecular levels with both temporal and spatial precision are necessary to make improve the management and drug development for pharmacoresistant epilepsy in the clinical arena.
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Affiliation(s)
- Cenglin Xu
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yiwei Gong
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yi Wang
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China; Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Zhong Chen
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China; Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China; Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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14
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Ahnaou A, Drinkenburg WHIM. Sleep, neuronal hyperexcitability, inflammation and neurodegeneration: Does early chronic short sleep trigger and is it the key to overcoming Alzheimer's disease? Neurosci Biobehav Rev 2021; 129:157-179. [PMID: 34214513 DOI: 10.1016/j.neubiorev.2021.06.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 05/13/2021] [Accepted: 06/25/2021] [Indexed: 01/13/2023]
Abstract
Evidence links neuroinflammation to Alzheimer's disease (AD); however, its exact contribution to the onset and progression of the disease is poorly understood. Symptoms of AD can be seen as the tip of an iceberg, consisting of a neuropathological build-up in the brain of extracellular amyloid-β (Aβ) plaques and intraneuronal hyperphosphorylated aggregates of Tau (pTau), which are thought to stem from an imbalance between its production and clearance resulting in loss of synaptic health and dysfunctional cortical connectivity. The glymphatic drainage system, which is particularly active during sleep, plays a key role in the clearance of proteinopathies. Poor sleep can cause hyperexcitability and promote Aβ and tau pathology leading to systemic inflammation. The early neuronal hyperexcitability of γ-aminobutyric acid (GABA)-ergic inhibitory interneurons and impaired inhibitory control of cortical pyramidal neurons lie at the crossroads of excitatory/inhibitory imbalance and inflammation. We outline, with a prospective framework, a possible vicious spiral linking early chronic short sleep, neuronal hyperexcitability, inflammation and neurodegeneration. Understanding the early predictors of AD, through an integrative approach, may hold promise for reducing attrition in the late stages of neuroprotective drug development.
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Affiliation(s)
- A Ahnaou
- Dept. of Neuroscience Discovery, Janssen Research & Development, A Division of Janssen Pharmaceutica NV, Turnhoutseweg 30, Beerse, B-2340, Belgium.
| | - W H I M Drinkenburg
- Dept. of Neuroscience Discovery, Janssen Research & Development, A Division of Janssen Pharmaceutica NV, Turnhoutseweg 30, Beerse, B-2340, Belgium
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15
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Wu YJ, Chien ME, Chiang CC, Huang YZ, Durand DM, Hsu KS. Delta oscillation underlies the interictal spike changes after repeated transcranial direct current stimulation in a rat model of chronic seizures. Brain Stimul 2021; 14:771-779. [PMID: 33989818 DOI: 10.1016/j.brs.2021.04.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 04/27/2021] [Accepted: 04/29/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS) provides a noninvasive polarity-specific constant current to treat epilepsy, through a mechanism possibly involving excitability modulation and neural oscillation. OBJECTIVE To determine whether EEG oscillations underlie the interictal spike changes after tDCS in rats with chronic spontaneous seizures. METHODS Rats with kainic acid-induced spontaneous seizures were subjected to cathodal tDCS or sham stimulation for 5 consecutive days. Video-EEG recordings were collected immediately pre- and post-stimulation and for the subsequent 2 weeks following stimulation. The acute pre-post stimulation and subacute follow-up changes of interictal spikes and EEG oscillations in tDCS-treated rats were compared with sham. Ictal EEG with seizure behaviors, hippocampal brain-derived neurotrophic factor (BDNF) protein expression, and mossy fiber sprouting were compared between tDCS and sham rats. RESULTS Interictal spike counts were reduced immediately following tDCS with augmented delta and diminished beta and gamma oscillations compared with sham. Cathodal tDCS also enhanced delta oscillations in normal rats. However, increased numbers of interictal spikes with a decrease of delta and theta oscillations were observed in tDCS-treated rats compared with sham during the following 2 weeks after stimulation. Resuming tDCS suppressed the increase of interictal spike activity. In tDCS rats, hippocampal BDNF protein expression was decreased while mossy fiber sprouting did not change compared with sham. CONCLUSIONS The inverse relationship between the changes of delta oscillation and interictal spikes during tDCS on and off stimulation periods indicates that an enhanced endogenous delta oscillation underlies the tDCS inhibitory effect on epileptic excitability.
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Affiliation(s)
- Yi-Jen Wu
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 70457, Taiwan; Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan.
| | - Miao-Er Chien
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 70457, Taiwan
| | - Chia-Chu Chiang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ying-Zu Huang
- Department of Neurology and Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan City, Taiwan; Medical School and Healthy Aging Research Center, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Institute of Cognitive Neuroscience, National Central University, Taoyuan, Taiwan
| | - Dominique M Durand
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kuei-Sen Hsu
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
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16
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Mihály I, Molnár T, Berki ÁJ, Bod RB, Orbán-Kis K, Gáll Z, Szilágyi T. Short-Term Amygdala Low-Frequency Stimulation Does not Influence Hippocampal Interneuron Changes Observed in the Pilocarpine Model of Epilepsy. Cells 2021; 10:cells10030520. [PMID: 33804543 PMCID: PMC7998440 DOI: 10.3390/cells10030520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/19/2021] [Accepted: 02/25/2021] [Indexed: 11/23/2022] Open
Abstract
Temporal lobe epilepsy (TLE) is characterized by changes in interneuron numbers in the hippocampus. Deep brain stimulation (DBS) is an emerging tool to treat TLE seizures, although its mechanisms are not fully deciphered. We aimed to depict the effect of amygdala DBS on the density of the most common interneuron types in the CA1 hippocampal subfield in the lithium-pilocarpine model of epilepsy. Status epilepticus was induced in male Wistar rats. Eight weeks later, a stimulation electrode was implanted to the left basolateral amygdala of both pilocarpine-treated (Pilo, n = 14) and age-matched control rats (n = 12). Ten Pilo and 4 control animals received for 10 days 4 daily packages of 50 s 4 Hz regular stimulation trains. At the end of the stimulation period, interneurons were identified by immunolabeling for parvalbumin (PV), neuropeptide Y (NPY), and neuronal nitric oxide synthase (nNOS). Cell density was determined in the CA1 subfield of the hippocampus using confocal microscopy. We found that PV+ cell density was preserved in pilocarpine-treated rats, while the NPY+/nNOS+ cell density decreased significantly. The amygdala DBS did not significantly change the cell density in healthy or in epileptic animals. We conclude that DBS with low frequency applied for 10 days does not influence interneuron cell density changes in the hippocampus of epileptic rats.
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Affiliation(s)
- István Mihály
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (T.M.); (Á.-J.B.); (R.-B.B.); (K.O.-K.); (T.S.)
- Correspondence: ; Tel.: +40-749-768-257
| | - Tímea Molnár
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (T.M.); (Á.-J.B.); (R.-B.B.); (K.O.-K.); (T.S.)
| | - Ádám-József Berki
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (T.M.); (Á.-J.B.); (R.-B.B.); (K.O.-K.); (T.S.)
| | - Réka-Barbara Bod
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (T.M.); (Á.-J.B.); (R.-B.B.); (K.O.-K.); (T.S.)
| | - Károly Orbán-Kis
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (T.M.); (Á.-J.B.); (R.-B.B.); (K.O.-K.); (T.S.)
| | - Zsolt Gáll
- Department of Pharmacology and Clinical Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania;
| | - Tibor Szilágyi
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (T.M.); (Á.-J.B.); (R.-B.B.); (K.O.-K.); (T.S.)
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17
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Application of Optogenetics in Epilepsy Research. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021. [PMID: 33398842 DOI: 10.1007/978-981-15-8763-4_39] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Epilepsy is a disease characterized by seizures arising from paroxysmal and self-limited hypersynchrony of neurons. However, the mechanism by which the normal brain develops epilepsy, which involves a chronic process of structural and morphological changes known as epileptogenesis, is not fully understood. Optogenetics involves the use of genetic engineering and optics to monitor or control nerve cell activity. Compared to classical electrophysiological experiments, the application of optogenetics in epilepsy research has many advantages because it allows selective photic stimulation of cell types and electrical observation without introducing artifacts.
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18
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Paschen E, Elgueta C, Heining K, Vieira DM, Kleis P, Orcinha C, Häussler U, Bartos M, Egert U, Janz P, Haas CA. Hippocampal low-frequency stimulation prevents seizure generation in a mouse model of mesial temporal lobe epilepsy. eLife 2020; 9:54518. [PMID: 33349333 PMCID: PMC7800381 DOI: 10.7554/elife.54518] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 12/13/2020] [Indexed: 12/18/2022] Open
Abstract
Mesial temporal lobe epilepsy (MTLE) is the most common form of focal, pharmacoresistant epilepsy in adults and is often associated with hippocampal sclerosis. Here, we established the efficacy of optogenetic and electrical low-frequency stimulation (LFS) in interfering with seizure generation in a mouse model of MTLE. Specifically, we applied LFS in the sclerotic hippocampus to study the effects on spontaneous subclinical and evoked generalized seizures. We found that stimulation at 1 Hz for 1 hr resulted in an almost complete suppression of spontaneous seizures in both hippocampi. This seizure-suppressive action during daily stimulation remained stable over several weeks. Furthermore, LFS for 30 min before a pro-convulsive stimulus successfully prevented seizure generalization. Finally, acute slice experiments revealed a reduced efficacy of perforant path transmission onto granule cells upon LFS. Taken together, our results suggest that hippocampal LFS constitutes a promising approach for seizure control in MTLE.
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Affiliation(s)
- Enya Paschen
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Claudio Elgueta
- Systemic and Cellular Neurophysiology, Institute for Physiology I, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Katharina Heining
- Biomicrotechnology, Department of Microsystems Engineering - IMTEK, Faculty of Engineering, University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
| | - Diego M Vieira
- Biomicrotechnology, Department of Microsystems Engineering - IMTEK, Faculty of Engineering, University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
| | - Piret Kleis
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Catarina Orcinha
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Center for Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Marlene Bartos
- Systemic and Cellular Neurophysiology, Institute for Physiology I, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Center for Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ulrich Egert
- Biomicrotechnology, Department of Microsystems Engineering - IMTEK, Faculty of Engineering, University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
| | - Philipp Janz
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany.,Center for Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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19
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Dynamic Transitions in Neuronal Network Firing Sustained by Abnormal Astrocyte Feedback. Neural Plast 2020; 2020:8864246. [PMID: 33299401 PMCID: PMC7704208 DOI: 10.1155/2020/8864246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/24/2020] [Accepted: 10/28/2020] [Indexed: 11/21/2022] Open
Abstract
Astrocytes play a crucial role in neuronal firing activity. Their abnormal state may lead to the pathological transition of neuronal firing patterns and even induce seizures. However, there is still little evidence explaining how the astrocyte network modulates seizures caused by structural abnormalities, such as gliosis. To explore the role of gliosis of the astrocyte network in epileptic seizures, we first established a direct astrocyte feedback neuronal network model on the basis of the hippocampal CA3 neuron-astrocyte model to simulate the condition of gliosis when astrocyte processes swell and the feedback to neurons increases in an abnormal state. We analyzed the firing pattern transitions of the neuronal network when astrocyte feedback starts to change via increases in both astrocyte feedback intensity and the connection probability of astrocytes to neurons in the network. The results show that as the connection probability and astrocyte feedback intensity increase, neuronal firing transforms from a nonepileptic synchronous firing state to an asynchronous firing state, and when astrocyte feedback starts to become abnormal, seizure-like firing becomes more severe and synchronized; meanwhile, the synchronization area continues to expand and eventually transforms into long-term seizure-like synchronous firing. Therefore, our results prove that astrocyte feedback can regulate the firing of the neuronal network, and when the astrocyte network develops gliosis, there will be an increase in the induction rate of epileptic seizures.
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20
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Köksal Ersöz E, Modolo J, Bartolomei F, Wendling F. Neural mass modeling of slow-fast dynamics of seizure initiation and abortion. PLoS Comput Biol 2020; 16:e1008430. [PMID: 33166277 PMCID: PMC7676664 DOI: 10.1371/journal.pcbi.1008430] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 11/19/2020] [Accepted: 10/08/2020] [Indexed: 12/31/2022] Open
Abstract
Epilepsy is a dynamic and complex neurological disease affecting about 1% of the worldwide population, among which 30% of the patients are drug-resistant. Epilepsy is characterized by recurrent episodes of paroxysmal neural discharges (the so-called seizures), which manifest themselves through a large-amplitude rhythmic activity observed in depth-EEG recordings, in particular in local field potentials (LFPs). The signature characterizing the transition to seizures involves complex oscillatory patterns, which could serve as a marker to prevent seizure initiation by triggering appropriate therapeutic neurostimulation methods. To investigate such protocols, neurophysiological lumped-parameter models at the mesoscopic scale, namely neural mass models, are powerful tools that not only mimic the LFP signals but also give insights on the neural mechanisms related to different stages of seizures. Here, we analyze the multiple time-scale dynamics of a neural mass model and explain the underlying structure of the complex oscillations observed before seizure initiation. We investigate population-specific effects of the stimulation and the dependence of stimulation parameters on synaptic timescales. In particular, we show that intermediate stimulation frequencies (>20 Hz) can abort seizures if the timescale difference is pronounced. Those results have the potential in the design of therapeutic brain stimulation protocols based on the neurophysiological properties of tissue.
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Affiliation(s)
| | - Julien Modolo
- University of Rennes, Inserm-U1099, LTSI, Rennes, France
| | - Fabrice Bartolomei
- Aix Marseille University, Inserm, INS, Institut de Neurosciences des Systèmes, Marseille, France
- APHM, Timone Hospital, Clinical Neurophysiology, Marseille, France
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21
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Cela E, Sjöström PJ. Novel Optogenetic Approaches in Epilepsy Research. Front Neurosci 2019; 13:947. [PMID: 31551699 PMCID: PMC6743373 DOI: 10.3389/fnins.2019.00947] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 08/22/2019] [Indexed: 11/13/2022] Open
Abstract
Epilepsy is a major neurological disorder characterized by repeated seizures afflicting 1% of the global population. The emergence of seizures is associated with several comorbidities and severely decreases the quality of life of patients. Unfortunately, around 30% of patients do not respond to first-line treatment using anti-seizure drugs (ASDs). Furthermore, it is still unclear how seizures arise in the healthy brain. Therefore, it is critical to have well developed models where a causal understanding of epilepsy can be investigated. While the development of seizures has been studied in several animal models, using chemical or electrical induction, deciphering the results of such studies has been difficult due to the uncertainty of the cell population being targeted as well as potential confounds such as brain damage from the procedure itself. Here we describe novel approaches using combinations of optical and genetic methods for studying epileptogenesis. These approaches can circumvent some shortcomings associated with the classical animal models and may thus increase the likelihood of developing new treatment options.
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Affiliation(s)
- Elvis Cela
- Brain Repair and Integrative Neuroscience Program, Centre for Research in Neuroscience, Department of Medicine, Department of Neurology and Neurosurgery, The Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, QC, Canada.,Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Per Jesper Sjöström
- Brain Repair and Integrative Neuroscience Program, Centre for Research in Neuroscience, Department of Medicine, Department of Neurology and Neurosurgery, The Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, QC, Canada
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22
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Zangiabadi N, Ladino LD, Sina F, Orozco-Hernández JP, Carter A, Téllez-Zenteno JF. Deep Brain Stimulation and Drug-Resistant Epilepsy: A Review of the Literature. Front Neurol 2019; 10:601. [PMID: 31244761 PMCID: PMC6563690 DOI: 10.3389/fneur.2019.00601] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 05/21/2019] [Indexed: 01/08/2023] Open
Abstract
Introduction: Deep brain stimulation is a safe and effective neurointerventional technique for the treatment of movement disorders. Electrical stimulation of subcortical structures may exert a control on seizure generators initiating epileptic activities. The aim of this review is to present the targets of the deep brain stimulation for the treatment of drug-resistant epilepsy. Methods: We performed a structured review of the literature from 1980 to 2018 using Medline and PubMed. Articles assessing the impact of deep brain stimulation on seizure frequency in patients with DRE were selected. Meta-analyses, randomized controlled trials, and observational studies were included. Results: To date, deep brain stimulation of various neural targets has been investigated in animal experiments and humans. This article presents the use of stimulation of the anterior and centromedian nucleus of the thalamus, hippocampus, basal ganglia, cerebellum and hypothalamus. Anterior thalamic stimulation has demonstrated efficacy and there is evidence to recommend it as the target of choice. Conclusion: Deep brain stimulation for seizures may be an option in patients with drug-resistant epilepsy. Anterior thalamic nucleus stimulation could be recommended over other targets.
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Affiliation(s)
- Nasser Zangiabadi
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
- Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran
| | - Lady Diana Ladino
- Epilepsy Program, Hospital Pablo Tobón Uribe, Neuroclinica, University of Antioquia, Medellín, Colombia
| | - Farzad Sina
- Department of Neurology, Rasool Akram Hospital, IUMS, Tehran, Iran
| | - Juan Pablo Orozco-Hernández
- Departamento de Investigación Clínica, Facultad de Ciencias de la Salud, Universidad Tecnológica de Pereira-Clínica Comfamiliar, Pereira, Colombia
| | - Alexandra Carter
- Saskatchewan Epilepsy Program, Department of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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23
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Wang Y, Chen Z. An update for epilepsy research and antiepileptic drug development: Toward precise circuit therapy. Pharmacol Ther 2019; 201:77-93. [PMID: 31128154 DOI: 10.1016/j.pharmthera.2019.05.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 12/14/2022]
Abstract
Epilepsy involves neuronal dysfunction at molecular, cellular, and circuit levels. The understanding of the mechanism of the epilepsies has advanced greatly in the last three decades, especially in terms of their cellular and molecular basis. However, despite the availability of ~30 anti-epileptic drugs (AEDs) with diverse molecular targets, there are still many challenges (e.g. drug resistance, side effects) in pharmacological treatment of epilepsies today. Because molecular mechanisms are integrated at the level of neuronal circuits, we suggest a shift in epilepsy treatment and research strategies from the "molecular" level to the "circuit" level. Recent technological advances have facilitated circuit mechanistic discovery at each level and have paved the way for many opportunities of novel therapeutic strategies and AED development toward precise circuit therapy.
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Affiliation(s)
- Yi Wang
- Institute of Pharmacology and Toxicology, Department of Pharmacology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Zhong Chen
- Institute of Pharmacology and Toxicology, Department of Pharmacology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China.
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Markert MS, Fisher RS. Neuromodulation - Science and Practice in Epilepsy: Vagus Nerve Stimulation, Thalamic Deep Brain Stimulation, and Responsive NeuroStimulation. Expert Rev Neurother 2018; 19:17-29. [DOI: 10.1080/14737175.2019.1554433] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Matthew S. Markert
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - Robert S. Fisher
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
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Couturier NH, Durand DM. Corpus callosum low-frequency stimulation suppresses seizures in an acute rat model of focal cortical seizures. Epilepsia 2018; 59:2219-2230. [PMID: 30426470 PMCID: PMC6279515 DOI: 10.1111/epi.14595] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 10/15/2018] [Accepted: 10/15/2018] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Low-frequency fiber-tract stimulation has been shown to be effective in treating mesial temporal lobe epilepsies through activation of the hippocampal commissure in rodents and human patients. The corpus callosum is a major pathway connecting the two hemispheres of the brain; however, few experiments have documented corpus callosum stimulation. The objective is to determine the efficacy of corpus callosum stimulation at low frequencies to suppress cortical seizures. METHODS 4-Aminopyridine was injected in the primary motor cortex of 24 rats under anesthesia. Recording electrodes were placed in the contralateral motor cortex and hippocampus. Three pairs of stimulating electrodes were inserted into the corpus callosum along its longitudinal axis. Local field potentials were recorded 1 hour before, during, and after stimulation to determine the effect of stimulation on seizure duration. Stimulation was delivered from each pair of electrodes independently in separate experiments. Furthermore, electrical stimulation was applied to the region of the corpus callosum with the highest degree of innervation of the seizure focus to compare the efficacy of different stimulation frequencies (1-30 Hz) on seizure suppression. RESULTS Corpus callosum stimulation was effective at suppressing seizures at 10 Hz by 76% (P < 0.05, n = 5) and at 20 Hz by 95% (P < 0.0001, n = 14). Stimulation at frequencies of 1 and 30 Hz did not have a significant effect on reducing the total time spent seizing (P > 0.9999, n = 5). Furthermore, stimulation was only effective at suppressing seizures when the pair of electrodes was placed within the section of corpus callosum containing fibers innervating the seizure focus. Secondarily generalized seizures in the hippocampus were eliminated when seizures in the cortical focus were suppressed. SIGNIFICANCE Low-frequency fiber-tract stimulation of the corpus callosum suppresses both cortical and cortically induced hippocampal seizures in an acute model of focal cortical seizures. The stimulation paradigm is selective, as it is only effective when targeted to specific regions of the corpus callosum that project maximally to cortical regions generating the seizure activity. Selective placement of stimulation electrodes along the corpus callosum could be used as a patient-specific treatment for cortical epilepsies.
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Affiliation(s)
- Nicholas H. Couturier
- Department of Biomedical Engineering, Neural Engineering Center, Case Western Reserve University, Cleveland, OH, U.S.A
| | - Dominique M. Durand
- Department of Biomedical Engineering, Neural Engineering Center, Case Western Reserve University, Cleveland, OH, U.S.A
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Cavarsan CF, Malheiros J, Hamani C, Najm I, Covolan L. Is Mossy Fiber Sprouting a Potential Therapeutic Target for Epilepsy? Front Neurol 2018; 9:1023. [PMID: 30555406 PMCID: PMC6284045 DOI: 10.3389/fneur.2018.01023] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 11/13/2018] [Indexed: 11/13/2022] Open
Abstract
Mesial temporal lobe epilepsy (MTLE) caused by hippocampal sclerosis is one of the most frequent focal epilepsies in adults. It is characterized by focal seizures that begin in the hippocampus, sometimes spread to the insulo-perisylvian regions and may progress to secondary generalized seizures. Morphological alterations in hippocampal sclerosis are well defined. Among them, hippocampal sclerosis is characterized by prominent cell loss in the hilus and CA1, and abnormal mossy fiber sprouting (granular cell axons) into the dentate gyrus inner molecular layer. In this review, we highlight the role of mossy fiber sprouting in seizure generation and hippocampal excitability and discuss the response of alternative treatment strategies in terms of MFS and spontaneous recurrent seizures in models of TLE (temporal lobe epilepsy).
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Affiliation(s)
- Clarissa F Cavarsan
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Jackeline Malheiros
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Clement Hamani
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil.,Harquail Centre for Neuromodulation, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada
| | - Imad Najm
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Luciene Covolan
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil.,Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, United States
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Qiu C, Feng Z, Zheng L, Huang L. Frequency-Dependent Inhibition Induced by Stimulations in Rat Hippocampus. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:2182-2185. [PMID: 30440837 DOI: 10.1109/embc.2018.8512613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Deep brain stimulation (DBS) has a good prospect in treating brain diseases such as epilepsy. However, its therapeutic mechanism is undetermined yet. To investigate the inhibitory effects of DBS acting on the downstream neurons in target region, 1-min pulse trains of orthodromic stimulations with various frequencies (10 - 100 Hz) were applied to the Schaffer collaterals of hippocampal CA1 region in anaesthetized rats. Unit spikes of downstream interneurons and pyramidal cells were detected and analyzed. Interneurons activated by the stimulation through mono-synaptic connections were recognized based on short latencies. Their firing was used as an index of stimulation-induced inhibition. Results showed that during stimulations with pulse frequency of 20 Hz, the mean firing rate of mono-synaptically-activated interneurons was significantly higher than the value during 10 Hz stimulations. Afterward, even if the pulse frequency increased to 100 Hz, the mean firing rate of the interneurons did not change significantly. However, only during stimulations with lower frequencies (10, 20 Hz), the firing of pyramidal cells was suppressed by the stimulation-activated interneurons. The inhibitory effects of interneurons were weakened during stimulations with higher frequencies (50 and 100 Hz). De-synchronous firing of interneurons induced by high-frequency stimulation might cause the loss of effective inhibition on the principal neurons. These findings provide new information for advancing the application of DBS.
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Magloire V, Mercier MS, Kullmann DM, Pavlov I. GABAergic Interneurons in Seizures: Investigating Causality With Optogenetics. Neuroscientist 2018; 25:344-358. [PMID: 30317911 PMCID: PMC6745605 DOI: 10.1177/1073858418805002] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Seizures are complex pathological network events characterized by excessive and
hypersynchronized activity of neurons, including a highly diverse population of
GABAergic interneurons. Although the primary function of inhibitory interneurons
under normal conditions is to restrain excitation in the brain, this system
appears to fail intermittently, allowing runaway excitation. Recent developments
in optogenetics, combined with genetic tools and advanced electrophysiological
and imaging techniques, allow us for the first time to assess the causal roles
of identified cell-types in network dynamics. While these methods have greatly
increased our understanding of cortical microcircuits in epilepsy, the roles
played by individual GABAergic cell-types in controlling ictogenesis remain
incompletely resolved. Indeed, the ability of interneurons to suppress epileptic
discharges varies across different subtypes, and an accumulating body of
evidence paradoxically implicates some interneuron subtypes in the initiation
and maintenance of epileptiform activity. Here, we bring together findings from
this growing field and discuss what can be inferred regarding the causal role of
different GABAergic cell-types in seizures.
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Affiliation(s)
- Vincent Magloire
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK
| | - Marion S Mercier
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK
| | - Dimitri M Kullmann
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK
| | - Ivan Pavlov
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK
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Camporeze B, Manica BA, Bonafé GA, Ferreira JJC, Diniz AL, de Oliveira CTP, Mathias Junior LR, de Aguiar PHP, Ortega MM. Optogenetics: the new molecular approach to control functions of neural cells in epilepsy, depression and tumors of the central nervous system. Am J Cancer Res 2018; 8:1900-1918. [PMID: 30416844 PMCID: PMC6220144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 09/14/2018] [Indexed: 06/09/2023] Open
Abstract
The optogenetic tools have been described as valuable techniques to study neural activity through light stimulation, as well as potential neuromodulator approaches in the management of several central nervous system (CNS) diseases. Since the first bacteriorhodopsin protein described as a single-component light-activated regulator of transmembrane ion flow description, in 1980's, the focus has been on channel proteins for neurobiology; however, the advances in engineering techniques showed involvement changes in cellular biological behavior in several types of proteins involved in cell cytoskeleton regulation, motility and gene expression. Although the use of this technology has been published in many papers, a question still remains regarding real results and potential clinical applicability in CNS diseases, as well as the publications scarcity that systematically analyses the published results. Lastly, the aim of this review is to discuss the experimental results, molecular mechanisms and potential clinical applications of optogenetic tools in epilepsy and depression treatment, as well as its applicability in the treatment of CNS tumors.
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Affiliation(s)
- Bruno Camporeze
- Postgraduate Program in Health Science, Laboratory of Cellular and Molecular Biology and Bioactive Compounds, São Francisco University (USF)Bragança Paulista-SP, Brazil
- Postgraduate Program in Health Science, Department of Neurosurgery, Institute of Medical Assistance of The State Public Servant (IAMSPE)São Paulo-SP, Brazil
| | - Bruno Alcântara Manica
- Departament of Neurology, Medical School University Pontifical University Catholic of São Paulo (PUCSP)Sorocaba-SP, Brazil
| | - Gabriel Alves Bonafé
- Postgraduate Program in Health Science, Laboratory of Cellular and Molecular Biology and Bioactive Compounds, São Francisco University (USF)Bragança Paulista-SP, Brazil
| | | | - Aurélio Lourenço Diniz
- Departament of Neurology, Medical School University Pontifical University Catholic of São Paulo (PUCSP)Sorocaba-SP, Brazil
| | | | | | - Paulo Henrique Pires de Aguiar
- Postgraduate Program in Health Science, Department of Neurosurgery, Institute of Medical Assistance of The State Public Servant (IAMSPE)São Paulo-SP, Brazil
- Departament of Neurology, Medical School University Pontifical University Catholic of São Paulo (PUCSP)Sorocaba-SP, Brazil
- Departament of Neurosurgery, Hospital Santa PaulaSão Paulo-SP, Brazil
- Department of Research and Innovation, Laboratory of Cellular and Molecular Biology, Medical School of ABC (FMABC)Santo André-SP, Brazil
| | - Manoela Marques Ortega
- Postgraduate Program in Health Science, Laboratory of Cellular and Molecular Biology and Bioactive Compounds, São Francisco University (USF)Bragança Paulista-SP, Brazil
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30
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Christenson Wick Z, Krook-Magnuson E. Specificity, Versatility, and Continual Development: The Power of Optogenetics for Epilepsy Research. Front Cell Neurosci 2018; 12:151. [PMID: 29962936 PMCID: PMC6010559 DOI: 10.3389/fncel.2018.00151] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 05/15/2018] [Indexed: 12/19/2022] Open
Abstract
Optogenetics is a powerful and rapidly expanding set of techniques that use genetically encoded light sensitive proteins such as opsins. Through the selective expression of these exogenous light-sensitive proteins, researchers gain the ability to modulate neuronal activity, intracellular signaling pathways, or gene expression with spatial, directional, temporal, and cell-type specificity. Optogenetics provides a versatile toolbox and has significantly advanced a variety of neuroscience fields. In this review, using recent epilepsy research as a focal point, we highlight how the specificity, versatility, and continual development of new optogenetic related tools advances our understanding of neuronal circuits and neurological disorders. We additionally provide a brief overview of some currently available optogenetic tools including for the selective expression of opsins.
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Affiliation(s)
- Zoé Christenson Wick
- Graduate Program in Neuroscience and Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
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31
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Zhao ML, Chen SJ, Li XH, Wang LN, Chen F, Zhong SJ, Yang C, Sun SK, Li JJ, Dong HJ, Dong YQ, Wang Y, Chen C. Optical Depolarization of DCX-Expressing Cells Promoted Cognitive Recovery and Maturation of Newborn Neurons via the Wnt/β-Catenin Pathway. J Alzheimers Dis 2018; 63:303-318. [PMID: 29614674 DOI: 10.3233/jad-180002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Ming-Liang Zhao
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Shi-Jin Chen
- Department of Cardiology, Yichang Second People’s Hospital, Hubei, China
| | - Xiao-Hong Li
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Li-Na Wang
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Feng Chen
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Shi-Jiang Zhong
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Cheng Yang
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Sheng-Kai Sun
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Jian-Jun Li
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Hua-Jiang Dong
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Yue-Qing Dong
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Yi Wang
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
| | - Chong Chen
- Tianjin Key Laboratory of Neurotrauma Repair, Pingjin Hospital Brain Center, Logistics University of Chinese People’s Armed Police Forces, Tianjin, China
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Dobbins DL, Klorig DC, Smith T, Godwin DW. Expression of channelrhodopsin-2 localized within the deep CA1 hippocampal sublayer in the Thy1 line 18 mouse. Brain Res 2018; 1679:179-184. [PMID: 29191773 PMCID: PMC5752121 DOI: 10.1016/j.brainres.2017.11.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/20/2017] [Accepted: 11/22/2017] [Indexed: 12/21/2022]
Abstract
Optogenetic proteins are powerful tools for advancing our understanding of neural circuitry. However, the precision of optogenetics is dependent in part on the extent to which expression is limited to cells of interest. The Thy1-ChR2 transgenic mouse is commonly used in optogenetic experiments. Although general expression patterns in these animals have been characterized, a detailed evaluation of cell-type specificity is lacking. This information is critical for interpretation of experimental results using these animals. We characterized ChR2 expression under the Thy1promoter in line 18 in comparison to known expression profiles of hippocampal cell types using immunohistochemistry in CA1. ChR2 expression did not colocalize with parvalbumin or calbindin expressing interneurons. However, we found ChR2 expression to be localized in the deep sublayer of CA1 in calbindin-negative pyramidal cells. These findings demonstrate the utility of the Thy1-ChR2-YFP mouse to study the activity and functional role of excitatory neurons located in the deep CA1 pyramidal cell layer.
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Affiliation(s)
- Dorothy L Dobbins
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
| | - David C Klorig
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Thuy Smith
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Dwayne W Godwin
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC, USA
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Ye H, Kaszuba S. Inhibitory or excitatory? Optogenetic interrogation of the functional roles of GABAergic interneurons in epileptogenesis. J Biomed Sci 2017; 24:93. [PMID: 29202749 PMCID: PMC5715558 DOI: 10.1186/s12929-017-0399-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/28/2017] [Indexed: 01/22/2023] Open
Abstract
Alteration in the excitatory/inhibitory neuronal balance is believed to be the underlying mechanism of epileptogenesis. Based on this theory, GABAergic interneurons are regarded as the primary inhibitory neurons, whose failure of action permits hyperactivity in the epileptic circuitry. As a consequence, optogenetic excitation of GABAergic interneurons is widely used for seizure suppression. However, recent evidence argues for the context-dependent, possibly “excitatory” roles that GABAergic cells play in epileptic circuitry. We reviewed current optogenetic approaches that target the “inhibitory” roles of GABAergic interneurons for seizure control. We also reviewed interesting evidence that supports the “excitatory” roles of GABAergic interneurons in epileptogenesis. GABAergic interneurons can provide excitatory effects to the epileptic circuits via several distinct neurological mechanisms. (1) GABAergic interneurons can excite postsynaptic neurons, due to the raised reversal potential of GABA receptors in the postsynaptic cells. (2) Continuous activity in GABAergic interneurons could lead to transient GABA depletion, which prevents their inhibitory effect on pyramidal cells. (3) GABAergic interneurons can synchronize network activity during seizure. (4) Some GABAergic interneurons inhibit other interneurons, causing disinhibition of pyramidal neurons and network hyperexcitability. The dynamic, context-dependent role that GABAergic interneurons play in seizure requires further investigation of their functions at single cell and circuitry level. New optogenetic protocols that target GABAergic inhibition should be explored for seizure suppression.
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Affiliation(s)
- Hui Ye
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd, Chicago, IL, 60660, USA.
| | - Stephanie Kaszuba
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd, Chicago, IL, 60660, USA
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Forcelli PA. Applications of optogenetic and chemogenetic methods to seizure circuits: Where to go next? J Neurosci Res 2017; 95:2345-2356. [PMID: 28791729 DOI: 10.1002/jnr.24135] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/05/2017] [Accepted: 07/14/2017] [Indexed: 01/02/2023]
Abstract
Epilepsy is the quintessential circuit disorder, with seizure activity propagating through anatomically constrained pathways. These pathways, necessary for normal sensory, motor, and cognitive function, are hijacked during seizures. Understanding the network architecture at the level of both local microcircuits and distributed macrocircuits may provide new therapeutic avenues for the treatment of epilepsy. Over the past decade, optogenetic and chemogenetic tools have enabled previously impossible levels of functional circuit mapping in neuroscience. In this review, examples of the application of optogenetics and chemogenetics to epilepsy are raised, the comparative strengths and weaknesses of these approaches are discussed for both preclinical and translational applications, and recent applications of these approaches in other areas of neuroscience are highlighted. These points are raised in an effort to highlight the potential of these methods to address additional unanswered questions in epilepsy.
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Affiliation(s)
- Patrick A Forcelli
- Department of Pharmacology & Physiology, Department of Neuroscience, and Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, DC
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An Optogenetic Approach for Investigation of Excitatory and Inhibitory Network GABA Actions in Mice Expressing Channelrhodopsin-2 in GABAergic Neurons. J Neurosci 2017; 36:5961-73. [PMID: 27251618 DOI: 10.1523/jneurosci.3482-15.2016] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 04/12/2016] [Indexed: 01/16/2023] Open
Abstract
UNLABELLED To investigate excitatory and inhibitory GABA actions in cortical neuronal networks, we present a novel optogenetic approach using a mouse knock-in line with conditional expression of channelrhodopsin-2 (ChR2) in GABAergic interneurons. During whole-cell recordings from hippocampal and neocortical slices from postnatal day (P) 2-P15 mice, photostimulation caused depolarization and excitation of interneurons and evoked barrages of postsynaptic GABAergic currents. Excitatory/inhibitory GABA actions on pyramidal cells were assessed by monitoring the alteration in the frequency of EPSCs during photostimulation of interneurons. We found that in slices from P2-P8 mice, photostimulation evoked an increase in EPSC frequency, whereas in P9-P15 mice the response switched to a reduction in EPSC frequency, indicating a developmental excitatory-to-inhibitory switch in GABA actions on glutamatergic neurons. Using a similar approach in urethane-anesthetized animals in vivo, we found that photostimulation of interneurons reduces EPSC frequency at ages P3-P9. Thus, expression of ChR2 in GABAergic interneurons of mice enables selective photostimulation of interneurons during the early postnatal period, and these mice display a developmental excitatory-to-inhibitory switch in GABA action in cortical slices in vitro, but so far show mainly inhibitory GABA actions on spontaneous EPSCs in the immature hippocampus and neocortex in vivo SIGNIFICANCE STATEMENT We report a novel optogenetic approach for investigating excitatory and inhibitory GABA actions in mice with conditional expression of channelrhodopsin-2 in GABAergic interneurons. This approach shows a developmental excitatory-to-inhibitory switch in the actions of GABA on glutamatergic neurons in neocortical and hippocampal slices from neonatal mouse pups in vitro, but also reveals inhibitory GABA actions in the neonatal mouse neocortex and hippocampus in vivo.
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36
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Wykes RC, Lignani G. Gene therapy and editing: Novel potential treatments for neuronal channelopathies. Neuropharmacology 2017; 132:108-117. [PMID: 28564577 DOI: 10.1016/j.neuropharm.2017.05.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/25/2017] [Accepted: 05/26/2017] [Indexed: 01/14/2023]
Abstract
Pharmaceutical treatment can be inadequate, non-effective, or intolerable for many people suffering from a neuronal channelopathy. Development of novel treatment options, particularly those with the potential to be curative is warranted. Gene therapy approaches can permit cell-specific modification of neuronal and circuit excitability and have been investigated experimentally as a therapy for numerous neurological disorders, with clinical trials for several neurodegenerative diseases ongoing. Channelopathies can arise from a wide array of gene mutations; however they usually result in periods of aberrant network excitability. Therefore gene therapy strategies based on up or downregulation of genes that modulate neuronal excitability may be effective therapy for a wide range of neuronal channelopathies. As many channelopathies are paroxysmal in nature, optogenetic or chemogenetic approaches may be well suited to treat the symptoms of these diseases. Recent advances in gene-editing technologies such as the CRISPR-Cas9 system could in the future result in entirely novel treatment for a channelopathy by repairing disease-causing channel mutations at the germline level. As the brain may develop and wire abnormally as a consequence of an inherited or de novo channelopathy, the choice of optimal gene therapy or gene editing strategy will depend on the time of intervention (germline, neonatal or adult). This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- R C Wykes
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK.
| | - G Lignani
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK.
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Wozny TA, Lipski WJ, Alhourani A, Kondylis ED, Antony A, Richardson RM. Effects of hippocampal low-frequency stimulation in idiopathic non-human primate epilepsy assessed via a remote-sensing-enabled neurostimulator. Exp Neurol 2017; 294:68-77. [PMID: 28495218 DOI: 10.1016/j.expneurol.2017.05.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 04/28/2017] [Accepted: 05/06/2017] [Indexed: 01/06/2023]
Abstract
Individuals with pharmacoresistant epilepsy remain a large and under-treated patient population. Continued technologic advancements in implantable neurostimulators have spurred considerable research efforts directed towards the development of novel antiepileptic stimulation therapies. However, the lack of adequate preclinical experimental platforms has precluded a detailed understanding of the differential effects of stimulation parameters on neuronal activity within seizure networks. In order to chronically monitor seizures and the effects of stimulation in a freely-behaving non-human primate with idiopathic epilepsy, we employed a novel simultaneous video-intracranial EEG recording platform using a state-of-the-art sensing-enabled, rechargeable clinical neurostimulator with real-time seizure detection and wireless data streaming capabilities. Using this platform, we were able to characterize the electrographic and semiologic features of the focal-onset, secondarily generalizing tonic-clonic seizures stably expressed in this animal. A series of acute experiments exploring low-frequency (2Hz) hippocampal stimulation identified a pulse width (150μs) and current amplitude (4mA) combination which maximally suppressed local hippocampal activity. These optimized stimulation parameters were then delivered to the seizure onset-side hippocampus in a series of chronic experiments. This long-term testing revealed that the suppressive effects of low-frequency hippocampal stimulation 1) diminish when delivered continuously but are maintained when stimulation is cycled on and off, 2) are dependent on circadian rhythms, and 3) do not necessarily confer seizure protective effects.
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Affiliation(s)
- Thomas A Wozny
- Brain Modulation Lab, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213, United States
| | - Witold J Lipski
- Brain Modulation Lab, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213, United States
| | - Ahmad Alhourani
- Brain Modulation Lab, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213, United States
| | - Efstathios D Kondylis
- Brain Modulation Lab, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213, United States
| | - Arun Antony
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, United States; University of Pittsburgh Comprehensive Epilepsy Center, Pittsburgh, PA 15213, United States
| | - R Mark Richardson
- Brain Modulation Lab, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213, United States; University of Pittsburgh Comprehensive Epilepsy Center, Pittsburgh, PA 15213, United States; University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, United States.
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Optogenetic Low-Frequency Stimulation of Specific Neuronal Populations Abates Ictogenesis. J Neurosci 2017; 37:2999-3008. [PMID: 28209738 DOI: 10.1523/jneurosci.2244-16.2017] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 01/27/2017] [Accepted: 02/09/2017] [Indexed: 11/21/2022] Open
Abstract
Despite many advances made in understanding the pathophysiology of epileptic disorders, seizures remain poorly controlled in approximately one-third of patients with mesial temporal lobe epilepsy. Here, we established the efficacy of cell type-specific low-frequency stimulation (LFS) in controlling ictogenesis in the mouse entorhinal cortex (EC) in an in vitro brain slice preparation. Specifically, we used 1 Hz optogenetic stimulation of calcium/calmodulin-dependent protein kinase II-positive principal cells as well as of parvalbumin- or somatostatin-positive interneurons to study the effects of such repetitive activation on epileptiform discharges induced by 4-aminopyridine. We found that 1 Hz stimulation of any of these cell types reduced the frequency and duration of ictal discharges in some trials, while completely blocking them in others. The field responses evoked by the stimulation of each cell type revealed that their duration and amplitude were higher when principal cells were targeted. Furthermore, following a short period of silence ranging from 67 to 135 s, ictal discharges were re-established with similar duration and frequency as before stimulation; however, this period of silence was longer following principal cell stimulation compared with parvalbumin- or somatostatin-positive interneuron stimulation. Our results show that LFS of either excitatory or inhibitory cell networks in EC are effective in controlling ictogenesis. Although optogenetic stimulation of either cell type significantly reduced the occurrence of ictal discharges, principal cell stimulation resulted in a more prolonged suppression of ictogenesis, and, thus, it may constitute a better approach for controlling seizures.SIGNIFICANCE STATEMENT Epilepsy is a neurological disorder characterized by an imbalance between excitation and inhibition leading to seizures. Many epileptic patients do not achieve adequate seizure control using antiepileptic drugs. Low-frequency stimulation (LFS) is an alternative tool for controlling epileptiform activity in these patients. However, despite the temporal and spatial control offered by LFS, such a procedure lacks cell specificity, which may limit its efficacy. Using an optogenetic approach, we report here that LFS of two interneuron subtypes and, even more so, of principal cells can reliably shorten or abolish seizures in vitro Our work suggests that targeted LFS may constitute a reliable means for controlling seizures in patients presenting with focal seizures.
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Tung JK, Berglund K, Gross RE. Optogenetic Approaches for Controlling Seizure Activity. Brain Stimul 2016; 9:801-810. [PMID: 27496002 PMCID: PMC5143193 DOI: 10.1016/j.brs.2016.06.055] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 06/21/2016] [Accepted: 06/28/2016] [Indexed: 01/01/2023] Open
Abstract
Optogenetics, a technique that utilizes light-sensitive ion channels or pumps to activate or inhibit neurons, has allowed scientists unprecedented precision and control for manipulating neuronal activity. With the clinical need to develop more precise and effective therapies for patients with drug-resistant epilepsy, these tools have recently been explored as a novel treatment for halting seizure activity in various animal models. In this review, we provide a detailed and current summary of these optogenetic approaches and provide a perspective on their future clinical application as a potential neuromodulatory therapy.
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Affiliation(s)
- Jack K Tung
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA; Department of Neurosurgery, Emory University, Atlanta, GA
| | - Ken Berglund
- Department of Neurosurgery, Emory University, Atlanta, GA
| | - Robert E Gross
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA; Department of Neurosurgery, Emory University, Atlanta, GA.
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Choy M, Duffy BA, Lee JH. Optogenetic study of networks in epilepsy. J Neurosci Res 2016; 95:2325-2335. [PMID: 27413006 PMCID: PMC5548626 DOI: 10.1002/jnr.23767] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/27/2016] [Accepted: 04/28/2016] [Indexed: 01/23/2023]
Abstract
Currently, approximately 30% of patients with epilepsy do not have adequate seizure control. A greater understanding of the underlying mechanisms by which seizures start or propagate could lead to new therapeutic strategies. The recent development of optogenetics, because of its unprecedented precision for controlling activity within distinct neuronal populations, has revolutionized neuroscience, including epilepsy research. This Review discusses recent breakthroughs made with optogenetics in epilepsy research. These breakthroughs include new insights into the key roles that different cell types play in mediating seizures as well as in the development of epilepsy. Subsequently, we discuss how targeting different brain regions and cell populations has opened up the possibility of highly specific therapies that can stop seizures on demand. Finally, we illustrate how combining newly available neuroscience tools with whole-brain imaging techniques will allow researchers to understand better the spread of seizures on a network level. © 2016 The Authors. Journal of Neuroscience Research Published by Wiley Periodicals, Inc.
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Affiliation(s)
- ManKin Choy
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California
| | - Ben A Duffy
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California
| | - Jin Hyung Lee
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California.,Department of Bioengineering, Stanford University, Stanford, California.,Department of Neurosurgery, Stanford University, Stanford, California.,Department of Electrical Engineering, Stanford University, Stanford, California
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Bui AD, Alexander A, Soltesz I. Seizing Control: From Current Treatments to Optogenetic Interventions in Epilepsy. Neuroscientist 2016; 23:68-81. [PMID: 26700888 DOI: 10.1177/1073858415619600] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The unpredictability and severity of seizures contribute to the debilitating nature of epilepsy. These factors also render the condition particularly challenging to treat, as an ideal treatment would need to detect and halt the pathological bursts of hyperactivity without disrupting normal brain activity. Optogenetic techniques offer promising tools to study and perhaps eventually treat this episodic disorder by controlling specific brain circuits in epileptic animals with great temporal precision. Here, we briefly review the current treatment options for patients with epilepsy. We then describe the many ways optogenetics has allowed us to untangle the microcircuits involved in seizure activity, and how it has, in some cases, changed our perception of previous theories of seizure generation. Control of seizures with light is no longer a dream, and has been achieved in numerous different animal models of epilepsy. Beyond its application as a seizure suppressor, we highlight another facet of optogenetics in epilepsy, namely the ability to create "on-demand" seizures, as a tool to systematically probe the dynamics of networks during seizure initiation and propagation. Finally, we look into the future to discuss the possibilities and challenges of translating optogenetic techniques to clinical use.
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Affiliation(s)
- Anh D Bui
- 1 Department of Neurosurgery, Stanford University, Stanford, CA, USA.,2 Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Allyson Alexander
- 1 Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Ivan Soltesz
- 1 Department of Neurosurgery, Stanford University, Stanford, CA, USA
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Implicating Interneurons: Optogenetic Studies Suggest That Interneurons Are Guilty of Contributing to Epileptiform Activity. Epilepsy Curr 2015; 15:213-6. [PMID: 26316871 DOI: 10.5698/1535-7511-15.4.213] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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