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Marchionni I, Oberoi M, Soltesz I, Alexander A. Ripple-related firing of identified deep CA1 pyramidal cells in chronic temporal lobe epilepsy in mice. Epilepsia Open 2019; 4:254-263. [PMID: 31168492 PMCID: PMC6546014 DOI: 10.1002/epi4.12310] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/02/2019] [Accepted: 01/19/2019] [Indexed: 01/06/2023] Open
Abstract
OBJECTIVE Temporal lobe epilepsy (TLE) is often associated with memory deficits. Reactivation of memory traces in the hippocampus occurs during sharp-wave ripples (SWRs; 140-250 Hz). To better understand the mechanisms underlying high-frequency oscillations and cognitive comorbidities in epilepsy, we evaluated how rigorously identified deep CA1 pyramidal cells (dPCs) discharge during SWRs in control and TLE mice. METHODS We used the unilateral intraamygdala kainate model of TLE in video-electroencephalography (EEG) verified chronically epileptic adult mice. Local field potential and single-cell recordings were performed using juxtacellular recordings from awake control and TLE mice resting on a spherical treadmill, followed by post hoc identification of the recorded cells. RESULTS Hippocampal SWRs in TLE mice occurred with increased intraripple frequency compared to control mice. The frequency of SWR events was decreased, whereas the overall frequency of SWRs, interictal epileptiform discharges, and high-frequency ripples (250-500 Hz) together was not altered. CA1 dPCs in TLE mice showed significantly increased firing during ripples as well as between the ripple events. The strength of ripple modulation of dPC discharges increased in TLE without alteration of the preferred phase of firing during the ripple waves. SIGNIFICANCE These juxtacellular electrophysiology data obtained from identified CA1 dPCs from chronically epileptic mice are in general agreement with recent findings indicating distortion of normal firing patterns during offline SWRs as a mechanism underlying deficits in memory consolidation in epilepsy. Because the primary seizure focus in our experiments was in the amygdala and we recorded from the CA1 region, these results are also in agreement with the presence of altered high-frequency oscillations in areas of secondary seizure spread.
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Affiliation(s)
- Ivan Marchionni
- Department of Anatomy & NeurobiologyUniversity of CaliforniaIrvineCalifornia
- Department of Biomedical Sciences and Padova Neuroscience CenterUniversity of PadovaPadovaItaly
| | - Michelle Oberoi
- Department of Anatomy & NeurobiologyUniversity of CaliforniaIrvineCalifornia
- University of CaliforniaRiverside School of MedicineRiversideCalifornia
| | - Ivan Soltesz
- Department of Anatomy & NeurobiologyUniversity of CaliforniaIrvineCalifornia
- Department of NeurosurgeryStanford UniversityStanfordCalifornia
| | - Allyson Alexander
- Department of NeurosurgeryAnschutz School of MedicineUniversity of Colorado DenverAuroraColorado
- Department of NeurosurgeryChildren's Hospital ColoradoAuroraColorado
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Farrell JS, Nguyen QA, Soltesz I. Resolving the Micro-Macro Disconnect to Address Core Features of Seizure Networks. Neuron 2019; 101:1016-1028. [PMID: 30897354 PMCID: PMC6430140 DOI: 10.1016/j.neuron.2019.01.043] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/14/2018] [Accepted: 01/18/2019] [Indexed: 02/07/2023]
Abstract
Current drug treatments for epilepsy attempt to broadly restrict excitability to mask a symptom, seizures, with little regard for the heterogeneous mechanisms that underlie disease manifestation across individuals. Here, we discuss the need for a more complete view of epilepsy, outlining how key features at the cellular and microcircuit level can significantly impact disease mechanisms that are not captured by the most common methodology to study epilepsy, electroencephalography (EEG). We highlight how major advances in neuroscience tool development now enable multi-scale investigation of fundamental questions to resolve the currently controversial understanding of seizure networks. These findings will provide essential insight into what has emerged as a disconnect between the different levels of investigation and identify new targets and treatment options.
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Affiliation(s)
- Jordan S Farrell
- Department of Neurosurgery, Stanford University, Stanford, CA, USA.
| | - Quynh-Anh Nguyen
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA.
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Logica T, Riviere S, Holubiec MI, Castilla R, Barreto GE, Capani F. Metabolic Changes Following Perinatal Asphyxia: Role of Astrocytes and Their Interaction with Neurons. Front Aging Neurosci 2016; 8:116. [PMID: 27445788 PMCID: PMC4921470 DOI: 10.3389/fnagi.2016.00116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 05/03/2016] [Indexed: 11/13/2022] Open
Abstract
Perinatal Asphyxia (PA) represents an important cause of severe neurological deficits including delayed mental and motor development, epilepsy, major cognitive deficits and blindness. The interaction between neurons, astrocytes and endothelial cells plays a central role coupling energy supply with changes in neuronal activity. Traditionally, experimental research focused on neurons, whereas astrocytes have been more related to the damage mechanisms of PA. Astrocytes carry out a number of functions that are critical to normal nervous system function, including uptake of neurotransmitters, regulation of pH and ion concentrations, and metabolic support for neurons. In this work, we aim to review metabolic neuron-astrocyte interactions with the purpose of encourage further research in this area in the context of PA, which is highly complex and its mechanisms and pathways have not been fully elucidated to this day.
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Affiliation(s)
- Tamara Logica
- Laboratorio de Citoarquitectura y Plasticidad Neuronal, Facultad de Medicina, Instituto de Investigaciones Cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABA Buenos Aires, Argentina
| | - Stephanie Riviere
- Laboratorio de Biología Molecular, Facultad de Medicina, Instituto de Investigaciones cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABA Buenos Aires, Argentina
| | - Mariana I Holubiec
- Laboratorio de Citoarquitectura y Plasticidad Neuronal, Facultad de Medicina, Instituto de Investigaciones Cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABA Buenos Aires, Argentina
| | - Rocío Castilla
- Laboratorio de Biología Molecular, Facultad de Medicina, Instituto de Investigaciones cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABA Buenos Aires, Argentina
| | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá Bogotá, Colombia
| | - Francisco Capani
- Laboratorio de Citoarquitectura y Plasticidad Neuronal, Facultad de Medicina, Instituto de Investigaciones Cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABABuenos Aires, Argentina; Departamento de Biología, Universidad Argentina JF KennedyBuenos Aires, Argentina; Investigador Asociado, Universidad Autónoma de ChileSantiago, Chile
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Slomianka L, Amrein I, Knuesel I, Sørensen JC, Wolfer DP. Hippocampal pyramidal cells: the reemergence of cortical lamination. Brain Struct Funct 2011; 216:301-17. [PMID: 21597968 PMCID: PMC3197924 DOI: 10.1007/s00429-011-0322-0] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 04/26/2011] [Indexed: 12/16/2022]
Abstract
The increasing resolution of tract-tracing studies has led to the definition of segments along the transverse axis of the hippocampal pyramidal cell layer, which may represent functionally defined elements. This review will summarize evidence for a morphological and functional differentiation of pyramidal cells along the radial (deep to superficial) axis of the cell layer. In many species, deep and superficial sublayers can be identified histologically throughout large parts of the septotemporal extent of the hippocampus. Neurons in these sublayers are generated during different periods of development. During development, deep and superficial cells express genes (Sox5, SatB2) that also specify the phenotypes of superficial and deep cells in the neocortex. Deep and superficial cells differ neurochemically (e.g. calbindin and zinc) and in their adult gene expression patterns. These markers also distinguish sublayers in the septal hippocampus, where they are not readily apparent histologically in rat or mouse. Deep and superficial pyramidal cells differ in septal, striatal, and neocortical efferent connections. Distributions of deep and superficial pyramidal cell dendrites and studies in reeler or sparsely GFP-expressing mice indicate that this also applies to afferent pathways. Histological, neurochemical, and connective differences between deep and superficial neurons may correlate with (patho-) physiological phenomena specific to pyramidal cells at different radial locations. We feel that an appreciation of radial subdivisions in the pyramidal cell layer reminiscent of lamination in other cortical areas may be critical in the interpretation of studies of hippocampal anatomy and function.
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Affiliation(s)
- Lutz Slomianka
- Institute of Anatomy, University of Zürich, 8057 Zürich, Switzerland.
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Erecinska M, Cherian S, A Silver I. Brain development and susceptibility to damage; ion levels and movements. Curr Top Dev Biol 2009; 69:139-86. [PMID: 16243599 DOI: 10.1016/s0070-2153(05)69006-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Responses of immature brains to physiological and pathological stimuli often differ from those in the adult. Because CNS function critically depends on ion movements, this chapter evaluates ion levels and gradients during ontogeny and their alterations in response to adverse conditions. Total brain Na(+) and Cl(-) content decreases during development, but K(+) content rises, reflecting shrinkage of the extracellular and increase in the intracellular water spaces and a reduction in total brain water volume. Unexpectedly, [K(+)](i) seems to fall during the first postnatal week, which should reduce [K(+)](i)/ [K(+)](e) and result in a lower V(m), consistent with experimental observations. Neuronal [Cl(-)](i) is high during early postnatal development, hence the opening of Cl(-) conduction pathways may lead to plasma membrane depolarization. Equivalent loss of K(+)(i) into a relatively large extracellular space leads to a smaller increase in [K(+)](e) in immature animals, while the larger reservoir of Ca(2+)(e) may result in a greater [Ca(2+)](i) rise. In vivo and in vitro studies show that compared with adult, developing brains are more resistant to hypoxic/ischemic ion leakage: increases in [K(+)](e) and decreases in [Ca(2+)](e) are slower and smaller, consistent with the known low level of energy utilization and better maintenance of [ATP]. Severe hypoxia/ischemia may, however, lead to large Ca(2+)(i) overload. Rises in [K(+)](e) during epileptogenesis in vivo are smaller and take longer to manifest themselves in immature brains, although the rate of K(+) clearance is slower. By contrast, in vitro studies suggest the existence of a period of enhanced vulnerability sometime during the developmental period. This chapter concludes that there is a great need for more information on ion changes during ontogeny and poses the question whether the rat is the most appropriate model for investigation of mechanisms of pathological changes in human neonates.
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Affiliation(s)
- Maria Erecinska
- Department of Anatomy, School of Veterinary Science, Bristol, United Kingdom
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Abstract
Seizures in the newborn period are common and frequently indicate serious underlying brain injury. Although accumulating evidence suggests that they may impair brain development, there are currently no evidence-based guidelines for evaluation and management of neonatal seizures. In this review, we will address some of the current controversies facing child neurologists and neonatologists, including how to define, monitor, and treat neonatal seizures.
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Affiliation(s)
- Hannah C Glass
- Departments of Neurology and Pediatrics, University of California, San Francisco, USA.
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Voss LJ, Sleigh JW, Barnard JPM, Kirsch HE. The Howling Cortex: Seizures and General Anesthetic Drugs. Anesth Analg 2008; 107:1689-703. [PMID: 18931234 DOI: 10.1213/ane.0b013e3181852595] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Curia G, Longo D, Biagini G, Jones RS, Avoli M. The pilocarpine model of temporal lobe epilepsy. J Neurosci Methods 2008; 172:143-57. [PMID: 18550176 PMCID: PMC2518220 DOI: 10.1016/j.jneumeth.2008.04.019] [Citation(s) in RCA: 734] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 04/17/2008] [Accepted: 04/18/2008] [Indexed: 01/17/2023]
Abstract
Understanding the pathophysiogenesis of temporal lobe epilepsy (TLE) largely rests on the use of models of status epilepticus (SE), as in the case of the pilocarpine model. The main features of TLE are: (i) epileptic foci in the limbic system; (ii) an “initial precipitating injury”; (iii) the so-called “latent period”; and (iv) the presence of hippocampal sclerosis leading to reorganization of neuronal networks. Many of these characteristics can be reproduced in rodents by systemic injection of pilocarpine; in this animal model, SE is followed by a latent period and later by the appearance of spontaneous recurrent seizures (SRSs). These processes are, however, influenced by experimental conditions such as rodent species, strain, gender, age, doses and routes of pilocarpine administration, as well as combinations with other drugs administered before and/or after SE. In the attempt to limit these sources of variability, we evaluated the methodological procedures used by several investigators in the pilocarpine model; in particular, we have focused on the behavioural, electrophysiological and histopathological findings obtained with different protocols. We addressed the various experimental approaches published to date, by comparing mortality rates, onset of SRSs, neuronal damage, and network reorganization. Based on the evidence reviewed here, we propose that the pilocarpine model can be a valuable tool to investigate the mechanisms involved in TLE, and even more so when standardized to reduce mortality at the time of pilocarpine injection, differences in latent period duration, variability in the lesion extent, and SRS frequency.
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Affiliation(s)
- Giulia Curia
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and Physiology, McGill University, Montreal, QC, Canada H3A 2B4
| | - Daniela Longo
- Dipartimento di Scienze Biomediche, Università di Modena e Reggio Emilia, 41100 Modena, Italy
| | - Giuseppe Biagini
- Dipartimento di Scienze Biomediche, Università di Modena e Reggio Emilia, 41100 Modena, Italy
| | - Roland S.G. Jones
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, United Kingdom
| | - Massimo Avoli
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and Physiology, McGill University, Montreal, QC, Canada H3A 2B4
- Dipartimento di Medicina Sperimentale, Università di Roma “La Sapienza”, 00185 Roma, Italy
- Corresponding author at: 3801 University, Room 794, Montreal, QC, Canada H3A 2B4. Tel.: +1 514 398 1955; fax: +1 514 398 8106.
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Abstract
The immature brain is intrinsically hyperexcitable, a feature that, despite being crucial for learning, synaptogenesis and neuronal plasticity, predisposes the neonate to seizures. Seizures represent the most common neurologic manifestation of impaired brain function in this age group. Importantly, although seizure-induced neuronal injury is minimal in the "healthy" neonatal brain, the "metabolically-compromised" brain appears more vulnerable. Even in the "healthy" brain, however, seizures result in impaired learning, enhanced susceptibility to further seizures, and increased risk of brain injury with seizures later in life, as a result of altered hippocampal circuitry. Given these findings, an aggressive approach to neonatal seizures appears warranted. However, our current conventional therapies (including phenobarbital, phenytoin, and benzodiazepines), even when used in combination, are often ineffective in controlling seizures. Lidocaine may yield better efficacy but requires more study. Recent animal data suggest that alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) antagonists such as topiramate may have a neuroprotective role. However, further work is needed to confirm the safety of excitatory amino acid antagonists in neonates because there remains a prevailing concern that such agents may impair normal neurodevelopmental processes.
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Affiliation(s)
- Elaine C Wirrell
- Division of Pediatric Neurology, Alberta Childrens Hospital, Calgary, Alberta, Canada.
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