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Karadenizli Taşkin S, Şahin D, Dede F, Ünal Halbutoğullari ZS, Sarihan M, Kurnaz Özbek S, Özsoy ÖD, Kasap M, Yazir Y, Ateş N. Endoplasmic reticulum stress produced by Thapsigargin affects the occurrence of spike-wave discharge by modulating unfolded protein response pathways and activating immune responses in a dose-dependent manner. Eur J Pharmacol 2024; 974:176613. [PMID: 38670446 DOI: 10.1016/j.ejphar.2024.176613] [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: 11/27/2023] [Revised: 04/23/2024] [Accepted: 04/24/2024] [Indexed: 04/28/2024]
Abstract
The Endoplasmic Reticulum (ER) is associated with many cellular functions, from post-transcriptional modifications to the proper folding of proteins, and disruption of these functions causes ER stress. Although the relationship between epileptic seizures and ER stress has been reported, the contribution of ER stress pathways to epileptogenesis is still unclear. This study aimed to investigate the possible effects of ER stress-related molecular pathways modulated by mild- and high-dose Thapsigargin (Tg) on absence epileptic activity, CACNA1H and immune responses in WAG/Rij rats. For this purpose, rats were divided into four groups; mild-dose (20 ng) Tg, high-dose (200 ng) Tg, saline, and DMSO and drugs administered intracerebroventriculary. EEG activity was recorded for 1 h and 24 h after drug administration following the baseline recording. In cortex and thalamus tissues, GRP78, ERp57, GAD153 protein changes (Western Blot), Eif2ak3, XBP-1, ATF6, CACNA1H mRNA expressions (RT-PCR), NF-κB and TNF-α levels (ELISA) were measured. Mild-dose-Tg administration resulted in increased spike-wave discharge (SWD) activity at the 24th hour compared to administration of saline, and high-dose-Tg and it also significantly increased the amount of GRP78 protein, the expression of Eif2ak3, XBP-1, and CACNA1H mRNA in the thalamus tissue. In contrast, high-dose-Tg administration suppressed SWD activity and significantly increased XBP-1 and ATF6 mRNA expression in the thalamus, and increased NF-κB and TNF-α levels. In conclusion, our findings indicate that Tg affects SWD occurrence by modulating the unfolded protein response pathway and activating inflammatory processes in a dose-dependent manner.
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Affiliation(s)
| | - Deniz Şahin
- Physiology Department, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Fazilet Dede
- Physiology Department, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | | | - Mehmet Sarihan
- Department of Medical Biology/Proteomics Laboratory, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Sema Kurnaz Özbek
- Department of Histology and Embryology, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Özgür Doğa Özsoy
- Department of Biochemistry, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Murat Kasap
- Department of Medical Biology/Proteomics Laboratory, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Yusufhan Yazir
- Stem Cell and Gene Therapy Research and Application Center, Kocaeli University, Kocaeli, Turkey; Department of Histology and Embryology, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Nurbay Ateş
- Physiology Department, Kocaeli University Medical Faculty, Kocaeli, Turkey.
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Hsieh H, Xu Q, Zhang Q, Yang F, Xu Y, Liu G, Liu R, Yu Q, Zhang Z, Lu G, Gu X, Zhang Z. Mapping progressive damage epicenters in epilepsy with generalized tonic-clonic seizures by causal structural covariance network density (CaSCNd). Brain Res 2024; 1828:148766. [PMID: 38242522 DOI: 10.1016/j.brainres.2024.148766] [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: 09/23/2023] [Revised: 11/28/2023] [Accepted: 01/12/2024] [Indexed: 01/21/2024]
Abstract
AIMS Mapping progressive patterns of structural damage in epilepsies with idiopathic and secondarily generalized tonic-clonic seizures with causal structural covariance networks and multiple analysis strategies. METHODS Patients with idiopathic generalized tonic-clonic seizures (IGTCS) (n = 114) and secondarily generalized tonic-clonic seizures (SGTCS) (n = 125) were recruited. Morphometric parameter of gray matter volume was analyzed on structural MRI. Structural covariance network based on granger causality analysis (CaSCN) was performed on the cross-sectional morphometric data sorted by disease durations of patients. Seed-based CaSCN analysis was firstly carried out to map the progressive and influential patterns of damage to thalamus-related structures. A novel technique for voxel-based CaSCN density (CaSCNd) analysis was further proposed, enabling for identifying the epicenter of structural brain damage during the disease process. RESULTS The thalamus-associated CaSCNs demonstrated different patterns of progressive damage in two types of generalized tonic-clonic seizures. In IGTCS, the structural damage was predominantly driven from the thalamus, and expanded to the cortex, while in SGTCS, the damage was predominantly driven from the cortex, and expanded to the thalamus through the basal ganglia. CaSCNd analysis revealed that the IGTCS had an out-effect epicenter in the thalamus, whereas the SGTCS had equipotent in- and out-effects in the thalamus, cortex, and basal ganglia. CONCLUSION CaSCN revealed distinct damage patterns in the two types of GTCS, featuring with measurement of structural brain damage from the accumulating effect over a relatively long time period. Our work provided evidence for understanding network impairment mechanism underlying different GTCSs.
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Affiliation(s)
- Hsinyu Hsieh
- Department of Diagnostic Radiology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China
| | - Qiang Xu
- Department of Diagnostic Radiology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China
| | - Qirui Zhang
- Department of Diagnostic Radiology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China
| | - Fang Yang
- Department of Neurology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China
| | - Yin Xu
- Institute of Neurology Anhui, University of Chinese Medicine, Hefei 230061, China
| | - Gaoping Liu
- Department of Diagnostic Radiology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China
| | - Ruoting Liu
- Department of Diagnostic Radiology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China
| | - Qianqian Yu
- Department of Diagnostic Radiology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China
| | - Zixuan Zhang
- Department of Diagnostic Radiology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China
| | - Guangming Lu
- Department of Diagnostic Radiology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China
| | - Xing Gu
- Department of Ultrasound, YanCheng 1(st) People Hospital, China
| | - Zhiqiang Zhang
- Department of Diagnostic Radiology, Affiliated Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China; State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing 210093, China.
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Dervinis M, Crunelli V. Spike-and-wave discharges of absence seizures in a sleep waves-constrained corticothalamic model. CNS Neurosci Ther 2024; 30:e14204. [PMID: 37032628 PMCID: PMC10915988 DOI: 10.1111/cns.14204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 03/18/2023] [Accepted: 03/24/2023] [Indexed: 04/11/2023] Open
Abstract
AIMS Recurrent network activity in corticothalamic circuits generates physiological and pathological EEG waves. Many computer models have simulated spike-and-wave discharges (SWDs), the EEG hallmark of absence seizures (ASs). However, these models either provided detailed simulated activity only in a selected territory (i.e., cortical or thalamic) or did not test whether their corticothalamic networks could reproduce the physiological activities that are generated by these circuits. METHODS Using a biophysical large-scale corticothalamic model that reproduces the full extent of EEG sleep waves, including sleep spindles, delta, and slow (<1 Hz) waves, here we investigated how single abnormalities in voltage- or transmitter-gated channels in the neocortex or thalamus led to SWDs. RESULTS We found that a selective increase in the tonic γ-aminobutyric acid type A receptor (GABA-A) inhibition of first-order thalamocortical (TC) neurons or a selective decrease in cortical phasic GABA-A inhibition is sufficient to generate ~4 Hz SWDs (as in humans) that invariably start in neocortical territories. Decreasing the leak conductance of higher-order TC neurons leads to ~7 Hz SWDs (as in rodent models) while maintaining sleep spindles at 7-14 Hz. CONCLUSION By challenging key features of current mechanistic views, this simulated ictal corticothalamic activity provides novel understanding of ASs and makes key testable predictions.
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Affiliation(s)
- Martynas Dervinis
- Neuroscience Division, School of BioscienceCardiff UniversityMuseum AvenueCardiffCF10 3AXUK
- Present address:
School of Physiology, Pharmacology and NeuroscienceBiomedical BuildingBristolBS8 1TDUK
| | - Vincenzo Crunelli
- Neuroscience Division, School of BioscienceCardiff UniversityMuseum AvenueCardiffCF10 3AXUK
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Characterization of cortical activity in juvenile myoclonic epilepsy by gradient magnetic field topography. Clin Neurophysiol 2022; 141:62-74. [PMID: 35853311 DOI: 10.1016/j.clinph.2022.06.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 06/16/2022] [Accepted: 06/27/2022] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Gradient magnetic field topography (GMFT) illustrates the magnetic field gradients of epileptic spike or polyspikes (S/PS) activities on a volume-rendered brain surface. The purpose is to characterize cortical activation in juvenile myoclonic epilepsy (JME). METHODS We compared interictal S/PS activities in 10 patients with JME to five patients with Lennox-Gastaut syndrome (LGS). We defined areas with gradients exceeding 300fT/cm as activated zones (AZs) on GMFT. We defined the hemisphere where an AZ initially appeared as the "preceding hemisphere". We localized the foci where AZs arose and evaluated their spatiotemporal changes. RESULTS In JME, the localization of S/PS in the preceding hemisphere was frontal in 18 activities (28%), parietal in 10 (15%), and frontal/parietal in 33 (51%), and in the contralateral hemisphere it was frontal in 14 (32%), parietal in 6 (14%), and frontal/parietal in 19 (43%). In LGS, AZs arose in every lobe of the brain. The median interhemispheric time difference was 7 ms (range: 0-20) in JME, which was significantly shorter than the 19 ms (1-50) observed among patients with LGS (p < 0.0001). CONCLUSIONS AZs are localized within the bilateral frontal and parietal regions. AZs arose serially from foci with small time differences. SIGNIFICANCE These results are consistent with regional network involvement in JME.
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Alterations in white matter integrity and asymmetry in patients with benign childhood epilepsy with centrotemporal spikes and childhood absence epilepsy: An automated fiber quantification tractography study. Epilepsy Behav 2021; 123:108235. [PMID: 34411950 DOI: 10.1016/j.yebeh.2021.108235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/11/2021] [Accepted: 07/19/2021] [Indexed: 01/05/2023]
Abstract
PURPOSE To investigate whether patients with benign childhood epilepsy with centrotemporal spikes (BECTS) and childhood absence epilepsy (CAE) show distinct patterns of white matter (WM) alterations and structural asymmetry compared with healthy controls and the relationship between WM alterations and epilepsy-related clinical variables. METHODS We used automated fiber quantification to create tract profiles of fractional anisotropy (FA) and mean diffusivity (MD) in twenty-six patients with BECTS, twenty-nine patients with CAE, and twenty-four healthy controls. Group differences in FA and MD were quantified at 100 equidistant nodes along the fiber tract and these alterations and epilepsy-related clinical variables were correlated. A lateralization index (LI) representing the structural asymmetry of the fiber tract was computed and compared between both patient groups and controls. RESULTS Compared with healthy controls, the BECTS group showed widespread FA reduction in 43.75% (7/16) and MD elevation in 50% (8/16) of identified fiber tracts, and the CAE group showed regional FA reduction in 31.25% (5/16) and MD elevation in 25% (4/16) of identified fiber tracts. In the BECTS group, FA and MD in the right anterior thalamic radiation positively and negatively correlated with the number of antiepileptic drugs, respectively, and MD in the right arcuate fasciculus (AF) positively correlated with seizure frequency. In the CAE group, the LI values were significantly lower in the inferior fronto-occipital fasciculus and the AF. CONCLUSION The two childhood epilepsy syndromes display different patterns of WM alterations and structural asymmetry, suggesting that neuroanatomical differences may underlie the different profiles of BECTS and CAE.
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Karadenizli S, Şahin D, Ateş N. Age dependent effects of Retigabine on absence seizure in WAG/Rij rats; an experimental study. Clin Exp Pharmacol Physiol 2021; 48:1251-1260. [PMID: 34133772 DOI: 10.1111/1440-1681.13537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 10/24/2019] [Accepted: 06/07/2021] [Indexed: 12/01/2022]
Abstract
Retigabine (RTG, Ezogabine, DC23129) is the first neuronal potassium channel opener in the treatment of epilepsy and exerts its effects through the activation of neuronal KCNQ2/3 potassium channels; in higher doses, it acts also on sodium and voltage-gated calcium channels. The aim of this study was to investigate possible age-dependent therapeutic effects of RTG on spike-and-wave discharges (SWD) in an animal model of absence epilepsy using WAG/Rij rats. In this study, 6- and 12-month-old WAG/Rij rats were used. For both age categories, three sub-groups that consisted of one control group (n=7) by the administration of 20% DMSO (control) and two study groups by the administration of 5 mg/kg (n=7) and 15 mg/kg RTG (n=7) were designed. EEG electrodes were placed onto the skull of anaesthetized animals; and baseline EEG was recorded for one hour after a recovery period from surgery. Then, the pre-determined two distinct doses of RTG and 20% DMSO were administered as a solvent via intraperitoneal injections, and EEG was recorded for 3 hours. After injection, both doses of RTG increased the total SWD number and duration of SWD in the first and second hours in 12-month-old rats. These parameters were elevated compared to 6-month-old rats. Age-dependent effects of RTG were observed in SWD activity. Pro-epileptic effects in middle-aged WAG/Rij rats were demonstrated in both RTG doses. Differences in the distribution of KCNQ2/3 channels and switch of GABAergic system from inhibitory to excitatory with age might contribute to increased SWD activity in middle-aged rats.
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Affiliation(s)
- Sabriye Karadenizli
- Department of Physiology, Medical Faculty of Kocaeli University, Kocaeli, Turkey
| | - Deniz Şahin
- Department of Physiology, Medical Faculty of Kocaeli University, Kocaeli, Turkey
| | - Nurbay Ateş
- Department of Physiology, Medical Faculty of Kocaeli University, Kocaeli, Turkey
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Hu B, Wang Z, Xu M, Zhu L, Wang D. The therapeutic mechanism of epilepsy seizures in different target areas: Research on a theoretical model. Technol Health Care 2021; 29:455-461. [PMID: 33682782 PMCID: PMC8150464 DOI: 10.3233/thc-218043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The selection of optimal target areas in the surgical treatment of epilepsy is always a difficult problem in medicine. OBJECTIVE We employed a theoretical calculation model to explore the control mechanism of seizures by an external voltage stimulus acting in different nerve nuclei. METHODS Theoretical analysis and numerical simulation were combined. RESULTS The globus pallidus, excitatory pyramidal neurons, striatal D1 neurons, thalamic reticular nucleus and specific relay nuclei were selected, we analyzed that the electrical stimulation has different effects in these target areas. CONCLUSIONS The data selected were reasonable in study, the results may give a theoretical support for similar studies in clinical.
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Affiliation(s)
- Bing Hu
- Department of Applied Mathematics, Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Zhizhi Wang
- Department of Applied Mathematics, Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Minbo Xu
- Department of Applied Mathematics, Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Luyao Zhu
- Department of Applied Mathematics, Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Dingjiang Wang
- Department of Applied Mathematics, Zhejiang University of Technology, Hangzhou, Zhejiang, China
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8
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Larivière S, Rodríguez-Cruces R, Royer J, Caligiuri ME, Gambardella A, Concha L, Keller SS, Cendes F, Yasuda C, Bonilha L, Gleichgerrcht E, Focke NK, Domin M, von Podewills F, Langner S, Rummel C, Wiest R, Martin P, Kotikalapudi R, O'Brien TJ, Sinclair B, Vivash L, Desmond PM, Alhusaini S, Doherty CP, Cavalleri GL, Delanty N, Kälviäinen R, Jackson GD, Kowalczyk M, Mascalchi M, Semmelroch M, Thomas RH, Soltanian-Zadeh H, Davoodi-Bojd E, Zhang J, Lenge M, Guerrini R, Bartolini E, Hamandi K, Foley S, Weber B, Depondt C, Absil J, Carr SJA, Abela E, Richardson MP, Devinsky O, Severino M, Striano P, Tortora D, Hatton SN, Vos SB, Duncan JS, Whelan CD, Thompson PM, Sisodiya SM, Bernasconi A, Labate A, McDonald CR, Bernasconi N, Bernhardt BC. Network-based atrophy modeling in the common epilepsies: A worldwide ENIGMA study. SCIENCE ADVANCES 2020; 6:6/47/eabc6457. [PMID: 33208365 PMCID: PMC7673818 DOI: 10.1126/sciadv.abc6457] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 10/05/2020] [Indexed: 06/10/2023]
Abstract
Epilepsy is increasingly conceptualized as a network disorder. In this cross-sectional mega-analysis, we integrated neuroimaging and connectome analysis to identify network associations with atrophy patterns in 1021 adults with epilepsy compared to 1564 healthy controls from 19 international sites. In temporal lobe epilepsy, areas of atrophy colocalized with highly interconnected cortical hub regions, whereas idiopathic generalized epilepsy showed preferential subcortical hub involvement. These morphological abnormalities were anchored to the connectivity profiles of distinct disease epicenters, pointing to temporo-limbic cortices in temporal lobe epilepsy and fronto-central cortices in idiopathic generalized epilepsy. Negative effects of age on atrophy further revealed a strong influence of connectome architecture in temporal lobe, but not idiopathic generalized, epilepsy. Our findings were reproduced across individual sites and single patients and were robust across different analytical methods. Through worldwide collaboration in ENIGMA-Epilepsy, we provided deeper insights into the macroscale features that shape the pathophysiology of common epilepsies.
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Affiliation(s)
- Sara Larivière
- Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Raúl Rodríguez-Cruces
- Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Jessica Royer
- Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | | | - Antonio Gambardella
- Neuroscience Research Center, University Magna Græcia, Catanzaro, CZ, Italy
- Institute of Neurology, University Magna Græcia, Catanzaro, CZ, Italy
| | - Luis Concha
- Institute of Neurobiology, Universidad Nacional Autónoma de México, Querétaro, México
| | - Simon S Keller
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
- Walton Centre NHS Foundation Trust, Liverpool, UK
| | - Fernando Cendes
- Department of Neurology, University of Campinas-UNICAMP, Campinas, São Paulo, Brazil
| | - Clarissa Yasuda
- Department of Neurology, University of Campinas-UNICAMP, Campinas, São Paulo, Brazil
| | - Leonardo Bonilha
- Department of Neurology, Medical University of South Carolina, Charleston, SC, USA
| | | | - Niels K Focke
- Department of Clinical Neurophysiology, University of Medicine Göttingen, Göttingen, Germany
| | - Martin Domin
- Institute of Diagnostic Radiology and Neuroradiology, Functional Imaging Unit, University Medicine Greifswald, Greifswald, Germany
| | - Felix von Podewills
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | - Soenke Langner
- Institute of Diagnostic Radiology and Neuroradiology, University Medicine Greifswald, Greifswald, Germany
| | - Christian Rummel
- Support Center for Advanced Neuroimaging (SCAN), University Institute of Diagnostic and Interventional Neuroradiology, University Hospital Bern, Bern, Switzerland
| | - Roland Wiest
- Support Center for Advanced Neuroimaging (SCAN), University Institute of Diagnostic and Interventional Neuroradiology, University Hospital Bern, Bern, Switzerland
| | - Pascal Martin
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Raviteja Kotikalapudi
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Alfred Hospital, Monash University, Melbourne, Victoria, Australia
- Departments of Medicine and Radiology, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
| | - Benjamin Sinclair
- Department of Neuroscience, Central Clinical School, Alfred Hospital, Monash University, Melbourne, Victoria, Australia
- Departments of Medicine and Radiology, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
| | - Lucy Vivash
- Department of Neuroscience, Central Clinical School, Alfred Hospital, Monash University, Melbourne, Victoria, Australia
- Departments of Medicine and Radiology, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
| | - Patricia M Desmond
- Departments of Medicine and Radiology, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
| | - Saud Alhusaini
- Department of Molecular and Cellular Therapeutics, The Royal College of Surgeons in Ireland, Dublin, Ireland
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
| | - Colin P Doherty
- Department of Neurology, St. James' Hospital, Dublin, Ireland
- FutureNeuro SFI Research Centre, Dublin, Ireland
| | - Gianpiero L Cavalleri
- Department of Molecular and Cellular Therapeutics, The Royal College of Surgeons in Ireland, Dublin, Ireland
- FutureNeuro SFI Research Centre, Dublin, Ireland
| | - Norman Delanty
- Department of Molecular and Cellular Therapeutics, The Royal College of Surgeons in Ireland, Dublin, Ireland
- FutureNeuro SFI Research Centre, Dublin, Ireland
| | - Reetta Kälviäinen
- Epilepsy Center, Neuro Center, Kuopio University Hospital, European Reference Network for Rare and Complex Epilepsies EpiCARE, Kuopio, Finland
- Faculty of Health Sciences, School of Medicine, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
| | - Graeme D Jackson
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Magdalena Kowalczyk
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Mario Mascalchi
- Neuroradiology Research Program, Meyer Children Hospital of Florence, University of Florence, Florence, Italy
| | - Mira Semmelroch
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Rhys H Thomas
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Hamid Soltanian-Zadeh
- Control and Intelligent Processing Center of Excellence (CIPCE), School of Electrical and Computer Engineering, University of Tehran, Tehran, Iran
- Departments of Research Administration and Radiology, Henry Ford Health System, Detroit, MI, USA
| | | | - Junsong Zhang
- Cognitive Science Department, Xiamen University, Xiamen, China
| | - Matteo Lenge
- Child Neurology Unit and Laboratories, Neuroscience Department, Children's Hospital A. Meyer-University of Florence, Italy
- Functional and Epilepsy Neurosurgery Unit, Neurosurgery Department, Children's Hospital A. Meyer-University of Florence, Italy
| | - Renzo Guerrini
- Child Neurology Unit and Laboratories, Neuroscience Department, Children's Hospital A. Meyer-University of Florence, Italy
| | - Emanuele Bartolini
- USL Centro Toscana, Neurology Unit, Nuovo Ospedale Santo Stefano, Prato, Italy
| | - Khalid Hamandi
- Cardiff University Brain Research Imaging Centre (CUBRIC), College of Biomedical Sciences, Cardiff University, Cardiff, UK
- Welsh Epilepsy Unit, Department of Neurology, University Hospital of Wales, Cardiff, UK
| | - Sonya Foley
- Welsh Epilepsy Unit, Department of Neurology, University Hospital of Wales, Cardiff, UK
| | - Bernd Weber
- Institute of Experimental Epileptology and Cognition Research, University Hospital Bonn, Bonn, Germany
| | - Chantal Depondt
- Department of Neurology, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Julie Absil
- Department of Radiology, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Sarah J A Carr
- Division of Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Eugenio Abela
- Division of Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Mark P Richardson
- Division of Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Orrin Devinsky
- Department of Neurology, NYU Grossman School of Medicine, New York, NY, USA
| | | | | | | | - Sean N Hatton
- Department of Neurosciences, Center for Multimodal Imaging and Genetics, University of California San Diego, La Jolla, CA, USA
| | - Sjoerd B Vos
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
- Chalfont Centre for Epilepsy, Bucks, UK
- Centre for Medical Image Computing, University College London, London, UK
| | - John S Duncan
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
- Chalfont Centre for Epilepsy, Bucks, UK
| | - Christopher D Whelan
- Department of Molecular and Cellular Therapeutics, The Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Paul M Thompson
- Imaging Genetics Center, Mark and Mary Stevens Institute for Neuroimaging and Informatics, USC Keck School of Medicine, Los Angeles, CA, USA
| | - Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
- Chalfont Centre for Epilepsy, Bucks, UK
| | - Andrea Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Angelo Labate
- Neuroscience Research Center, University Magna Græcia, Catanzaro, CZ, Italy
- Institute of Neurology, University Magna Græcia, Catanzaro, CZ, Italy
| | - Carrie R McDonald
- Department of Psychiatry, Center for Multimodal Imaging and Genetics, University of California San Diego, La Jolla, CA, USA
| | - Neda Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Boris C Bernhardt
- Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada.
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9
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Weng Y, Larivière S, Caciagli L, Vos de Wael R, Rodríguez-Cruces R, Royer J, Xu Q, Bernasconi N, Bernasconi A, Thomas Yeo BT, Lu G, Zhang Z, Bernhardt BC. Macroscale and microcircuit dissociation of focal and generalized human epilepsies. Commun Biol 2020; 3:244. [PMID: 32424317 PMCID: PMC7234993 DOI: 10.1038/s42003-020-0958-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 04/15/2020] [Indexed: 01/01/2023] Open
Abstract
Thalamo-cortical pathology plays key roles in both generalized and focal epilepsies, but there is little work directly comparing these syndromes at the level of whole-brain mechanisms. Using multimodal imaging, connectomics, and computational simulations, we examined thalamo-cortical and cortico-cortical signatures and underlying microcircuits in 96 genetic generalized (GE) and 107 temporal lobe epilepsy (TLE) patients, along with 65 healthy controls. Structural and functional network profiling highlighted extensive atrophy, microstructural disruptions and decreased thalamo-cortical connectivity in TLE, while GE showed only subtle structural anomalies paralleled by enhanced thalamo-cortical connectivity. Connectome-informed biophysical simulations indicated modest increases in subcortical drive contributing to cortical dynamics in GE, while TLE presented with reduced subcortical drive and imbalanced excitation-inhibition within limbic and somatomotor microcircuits. Multiple sensitivity analyses supported robustness. Our multiscale analyses differentiate human focal and generalized epilepsy at the systems-level, showing paradoxically more severe microcircuit and macroscale imbalances in the former.
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Affiliation(s)
- Yifei Weng
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Sara Larivière
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Lorenzo Caciagli
- University College London Queen Square Institute of Neurology, London, United Kingdom
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Reinder Vos de Wael
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Raúl Rodríguez-Cruces
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Jessica Royer
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Qiang Xu
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Neda Bernasconi
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Andrea Bernasconi
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - B T Thomas Yeo
- Department of Electrical and Computer Engineering, Centre for Sleep and Cognition, Clinical Imaging Research Centre and N.1 Institute for Health, National University of Singapore, Singapore, Singapore
| | - Guangming Lu
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Zhiqiang Zhang
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China.
| | - Boris C Bernhardt
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada.
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Cainelli E, Mioni G, Boniver C, Bisiacchi PS, Vecchi M. Time perception in childhood absence epilepsy: Findings from a pilot study. Epilepsy Behav 2019; 99:106460. [PMID: 31470222 DOI: 10.1016/j.yebeh.2019.106460] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 07/28/2019] [Accepted: 07/28/2019] [Indexed: 10/26/2022]
Abstract
OBJECTIVES With this explorative study, we aimed to examine time perception in children with childhood absence epilepsy (CAE) and to compare those children with a matched control group. The study also investigated the association between the neuropsychological performance of the group with CAE and time judgment. We hypothesize that children with CAE could fail in time perception and that this may be because of a common underlying substrate with executive impairments. METHODS Thirteen children with CAE, aged 6-13 years, and 17 healthy children were recruited. All children performed the time bisection task; the children with CAE also performed a cognitive and neuropsychological assessment. We performed a univariate analysis using each parameter of the bisection task (bisection point [BP]) and Weber ratio (WR) as dependent variables, the group (patients vs. controls) as fixed factors and age at evaluation and vocabulary scores as covariates. In the subgroup of patients, we correlated bisection task parameters with neuropsychological tests using a nonparametric partial correlation; the analysis has corrected for age at evaluation. RESULTS The BP and WR measures differed between controls and patients with CAE. In the subgroup of patients also performing a neuropsychological assessment, we found a correlation between the WR measure and performance on the inhibition test (r = -0.641, p = .025), coding test (r = -0.815, p = .014), and Trail Making Test B (TMT B) (r = 0.72, p = .042). CONCLUSIONS We found an altered time perception in a pilot study of a small group of children with CAE. A neurophysiological mechanism underlying CAE seems to influence cognitive and behavioral deficits and time sensibility.
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Affiliation(s)
- Elisa Cainelli
- Department of Development and Socialization, University of Padova, Italy; Child Neurology and Clinical Neurophysiology, Women's and Children's Health Department, Padua University Hospital, Padova, Italy.
| | - Giovanna Mioni
- Department of General Psychology, University of Padova, Italy.
| | - Clementina Boniver
- Child Neurology and Clinical Neurophysiology, Women's and Children's Health Department, Padua University Hospital, Padova, Italy.
| | - Patrizia S Bisiacchi
- Department of General Psychology, University of Padova, Italy; Padova Neuroscience Center, PNC.
| | - Marilena Vecchi
- Child Neurology and Clinical Neurophysiology, Women's and Children's Health Department, Padua University Hospital, Padova, Italy; Neuromotor Rehabilitation Center La Nostra Famiglia Association, Vicenza, Italy.
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11
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Ossenblok P, van Houdt P, Colon A, Stroink H, van Luijtelaar G. A network approach to investigate the bi-hemispheric synchrony in absence epilepsy. Clin Neurophysiol 2019; 130:1611-1619. [PMID: 31319290 DOI: 10.1016/j.clinph.2019.05.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/11/2019] [Accepted: 05/22/2019] [Indexed: 11/24/2022]
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12
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Wang Z, Larivière S, Xu Q, Vos de Wael R, Hong SJ, Wang Z, Xu Y, Zhu B, Bernasconi N, Bernasconi A, Zhang B, Zhang Z, Bernhardt BC. Community-informed connectomics of the thalamocortical system in generalized epilepsy. Neurology 2019; 93:e1112-e1122. [PMID: 31405905 DOI: 10.1212/wnl.0000000000008096] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 04/30/2019] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVE To study the intrinsic organization of the thalamocortical circuitry in patients with generalized epilepsy with tonic-clonic seizures (GTCS) via resting-state fMRI (rs-fMRI) connectome analysis and to evaluate its relation to drug response. METHODS In a prospectively followed-up sample of 41 patients and 27 healthy controls, we obtained rs-fMRI and structural MRI. After 1 year of follow-up, 27 patients were classified as seizure-free and 14 as drug-resistant. We examined connectivity within and between resting-state communities in cortical and thalamic subregions. In addition to comparing patients to controls, we examined associations with seizure control. We assessed reproducibility in an independent cohort of 21 patients. RESULTS Compared to controls, patients showed a more constrained network embedding of the thalamus, while frontocentral neocortical regions expressed increased functional diversity. Findings remained significant after regressing out thalamic volume and cortical thickness, suggesting independence from structural alterations. We observed more marked network imbalances in drug-resistant compared to seizure-free patients. Findings were similar in the reproducibility dataset. CONCLUSIONS Our findings suggest a pathoconnectomic mechanism of generalized epilepsy centered on diverging changes in cortical and thalamic connectivity. More restricted thalamic connectivity could reflect the tendency to engage in recursive thalamocortical loops, which may contribute to hyperexcitability. Conversely, increased connectional diversity of frontocentral networks may relay abnormal activity to an extended bilateral territory. Network imbalances were observed shortly after diagnosis and related to future drug response, suggesting clinical utility.
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Affiliation(s)
- Zhengge Wang
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Sara Larivière
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Qiang Xu
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Reinder Vos de Wael
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Seok-Jun Hong
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Zhongyuan Wang
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Yun Xu
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Bin Zhu
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Neda Bernasconi
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Andrea Bernasconi
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Bing Zhang
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Zhiqiang Zhang
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China
| | - Boris C Bernhardt
- From the Departments of Radiology (Z.W., B.Z., B.Z.) and Neurology (Z.W., Y.X.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China; Multimodal Imaging and Connectome Analysis Laboratory (Z.W., S.L., R.V.d.W., S.-J.H., B.C.B.) and Neuroimaging of Epilepsy Laboratory (S.-J.H., N.B., A.B.), McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Quebec, Canada; and Department of Medical Imaging (Q.X., Z.Z.), Jinling Hospital, Nanjing University School of Medicine, China.
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13
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Coenzyme Q10 increases absence seizures in WAG/Rij rats: The role of the nitric oxide pathway. Epilepsy Res 2019; 154:69-73. [DOI: 10.1016/j.eplepsyres.2019.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 04/12/2019] [Accepted: 05/01/2019] [Indexed: 01/11/2023]
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14
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He Y, Inoue T, Nomura S, Maruta Y, Kida H, Yamakawa T, Hirayama Y, Imoto H, Suzuki M. Limitations of Local Brain Cooling on Generalized Motor Seizures from Unknown Foci in Awake Rats. Neurol Med Chir (Tokyo) 2019; 59:147-153. [PMID: 30890681 PMCID: PMC6465526 DOI: 10.2176/nmc.oa.2018-0112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Local brain cooling of an epileptic focus at 15°C reduces the number of spikes on an electrocorticogram (ECoG), terminates seizures, and maintains neurological functions. In this study, we attempted to suppress generalized motor seizures (GMSs) by cooling a unilateral sensorimotor area. GMSs were induced in rats by intraperitoneal injection of bicuculline methiodide, an antagonist of gamma-aminobutyric acid. While monitoring the ECoG and behavior, the right sensorimotor cortex was cooled for 10 min using an implanted device. The number of spikes recorded from the cooled cortex significantly decreased to 71.2% and 62.5% compared with the control group at temperatures of 15 and 5°C (both P <0.01), respectively. The number of spikes recorded from the contralateral mirror cortex reduced to 61.7% and 62.7% (both P <0.05), respectively. The ECoG power also declined to 85% and 50% in the cooled cortex, and to 94% and 49% in the mirror cortex by the cooling at 15 and 5°C, respectively. The spikes regained in the middle of the cooling period at 15°C and in the late period at 5°C. Seizure-free durations during the 10-min periods of cooling at 15 and 5°C lasted for 4.1 ± 2.2 and 5.9 ± 1.1 min, respectively. Although temperature-dependent seizure alleviation was observed, the effect of local cortical cooling on GMSs was limited compared with the effect of local cooling of the epileptic focus on GSMs.
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Affiliation(s)
- Yeting He
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University
| | - Takao Inoue
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University
| | - Sadahiro Nomura
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University.,Epilepsy Center, Yamaguchi University Hospital
| | - Yuichi Maruta
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University
| | - Hiroyuki Kida
- Department of Physiology, Graduate School of Medicine, Yamaguchi University
| | - Toshitaka Yamakawa
- Department of Computer Science and Electrical Engineering, Graduate School of Science and Technology, Kumamoto University.,Priority Organization for Innovation and Excellence, Kumamoto University
| | - Yuya Hirayama
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University
| | - Hirochika Imoto
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University.,Epilepsy Center, Yamaguchi University Hospital
| | - Michiyasu Suzuki
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University
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15
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Salvati KA, Beenhakker MP. Out of thin air: Hyperventilation-triggered seizures. Brain Res 2019; 1703:41-52. [PMID: 29288644 PMCID: PMC6546426 DOI: 10.1016/j.brainres.2017.12.037] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 11/29/2017] [Accepted: 12/27/2017] [Indexed: 12/11/2022]
Abstract
Voluntary hyperventilation triggers seizures in the vast majority of people with absence epilepsy. The mechanisms that underlie this phenomenon remain unknown. Herein, we review observations - many made long ago - that provide insight into the relationship between breathing and absence seizures.
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Affiliation(s)
- Kathryn A Salvati
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22903, United States
| | - Mark P Beenhakker
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22903, United States.
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16
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Celli R, Santolini I, Guiducci M, van Luijtelaar G, Parisi P, Striano P, Gradini R, Battaglia G, Ngomba RT, Nicoletti F. The α2δ Subunit and Absence Epilepsy: Beyond Calcium Channels? Curr Neuropharmacol 2018; 15:918-925. [PMID: 28290248 PMCID: PMC5652034 DOI: 10.2174/1570159x15666170309105451] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/16/2017] [Accepted: 03/06/2017] [Indexed: 02/08/2023] Open
Abstract
Background: Spike-wave discharges, underlying absence seizures, are generated within a cortico-thalamo-cortical network that involves the somatosensory cortex, the reticular thalamic nucleus, and the ventrobasal thalamic nuclei. Activation of T-type voltage-sensitive calcium channels (VSCCs) contributes to the pathological oscillatory activity of this network, and some of the first-line drugs used in the treatment of absence epilepsy inhibit T-type calcium channels. The α2δ subunit is a component of high voltage-activated VSCCs (i.e., L-, N-, P/Q-, and R channels) and studies carried out in heterologous expression systems suggest that it may also associate with T channels. The α2δ subunit is also targeted by thrombospondins, which regulate synaptogenesis in the central nervous system. Objective: To discuss the potential role for the thrombospondin/α2δ axis in the pathophysiology of absence epilepsy. Methods: We searched PubMed articles for the terms “absence epilepsy”, “T-type voltage-sensitive calcium channels”, “α2δ subunit”, “ducky mice”, “pregabalin”, “gabapentin”, “thrombospondins”, and included papers focusing this Review's scope. Results: We moved from the evidence that mice lacking the α2δ-2 subunit show absence seizures and α2δ ligands (gabapentin and pregabalin) are detrimental in the treatment of absence epilepsy. This suggests that α2δ may be protective against absence epilepsy via a mechanism that does not involve T channels. We discuss the interaction between thrombospondins and α2δ and its potential relevance in the regulation of excitatory synaptic formation in the cortico-thalamo-cortical network. Conclusion: We speculate on the possibility that the thrombospondin/α2δ axis is critical for the correct functioning of the cortico-thalamo-cortical network, and that abnormalities in this axis may play a role in the pathophysiology of absence epilepsy.
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Affiliation(s)
- Roberta Celli
- I.R.C.C.S. Neuromed, Neuropharmacology Unit, Pozzilli, (IS), Italy
| | - Ines Santolini
- I.R.C.C.S. Neuromed, Neuropharmacology Unit, Pozzilli, (IS), Italy
| | - Michela Guiducci
- Departments of Neurosciences, Mental Health and Sensory Organs, Experimental Medicine, and Physiology and Pharmacology, University Sapienza, Rome, Italy
| | - Gilles van Luijtelaar
- Donders Centre for Cognition, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen. Netherlands
| | - Pasquale Parisi
- Departments of Neurosciences, Mental Health and Sensory Organs, Experimental Medicine, and Physiology and Pharmacology, University Sapienza, Rome, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, "G. Gaslini" Institute, Genova, Italy
| | - Roberto Gradini
- I.R.C.C.S. Neuromed, Neuropharmacology Unit, Pozzilli, (IS), Italy
| | | | - Richard T Ngomba
- University of Lincoln, School of Pharmacy, Lincoln, United Kingdom
| | - Ferdinando Nicoletti
- Department of Physiology and Pharmacology, University Sapienza, Piazzale Aldo Moro, 5, 00185 Rome, Italy
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17
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Seizure Detection and Network Dynamics of Generalized Convulsive Seizures: Towards Rational Designing of Closed-Loop Neuromodulation. NEUROSCIENCE JOURNAL 2018; 2017:9606213. [PMID: 29387712 PMCID: PMC5745672 DOI: 10.1155/2017/9606213] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/06/2017] [Accepted: 11/13/2017] [Indexed: 12/11/2022]
Abstract
Objective Studies have demonstrated the utility of closed-loop neuromodulation in treating focal onset seizures. There is an utmost need of neurostimulation therapy for generalized tonic-clonic seizures. The study goals are to map the thalamocortical network dynamics during the generalized convulsive seizures and identify targets for reliable seizure detection. Methods Local field potentials were recorded from bilateral cortex, hippocampi, and centromedian thalami in Sprague-Dawley rats. Pentylenetetrazol was used to induce multiple convulsive seizures. The performances of two automated seizure detection methods (line length and P-operators) as a function of different cortical and subcortical structures were estimated. Multiple linear correlations-Granger's Causality was used to determine the effective connectivity. Results Of the 29 generalized tonic-clonic seizures analyzed, line length detected 100% of seizures in all the channels while the P-operator detected only 35% of seizures. The detection latencies were shortest in the thalamus in comparison to the cortex. There was a decrease in amplitude correlation within the thalamocortical network during the seizure, and flow of information was decreased from thalamus to hippocampal-parietal nodes. Significance The preclinical study confirms thalamus as a superior target for automated detection of generalized seizures and modulation of synchrony to increase coupling may be a strategy to abate seizures.
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18
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Klein P, Dingledine R, Aronica E, Bernard C, Blümcke I, Boison D, Brodie MJ, Brooks-Kayal AR, Engel J, Forcelli PA, Hirsch LJ, Kaminski RM, Klitgaard H, Kobow K, Lowenstein DH, Pearl PL, Pitkänen A, Puhakka N, Rogawski MA, Schmidt D, Sillanpää M, Sloviter RS, Steinhäuser C, Vezzani A, Walker MC, Löscher W. Commonalities in epileptogenic processes from different acute brain insults: Do they translate? Epilepsia 2018; 59:37-66. [PMID: 29247482 PMCID: PMC5993212 DOI: 10.1111/epi.13965] [Citation(s) in RCA: 189] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2017] [Indexed: 12/12/2022]
Abstract
The most common forms of acquired epilepsies arise following acute brain insults such as traumatic brain injury, stroke, or central nervous system infections. Treatment is effective for only 60%-70% of patients and remains symptomatic despite decades of effort to develop epilepsy prevention therapies. Recent preclinical efforts are focused on likely primary drivers of epileptogenesis, namely inflammation, neuron loss, plasticity, and circuit reorganization. This review suggests a path to identify neuronal and molecular targets for clinical testing of specific hypotheses about epileptogenesis and its prevention or modification. Acquired human epilepsies with different etiologies share some features with animal models. We identify these commonalities and discuss their relevance to the development of successful epilepsy prevention or disease modification strategies. Risk factors for developing epilepsy that appear common to multiple acute injury etiologies include intracranial bleeding, disruption of the blood-brain barrier, more severe injury, and early seizures within 1 week of injury. In diverse human epilepsies and animal models, seizures appear to propagate within a limbic or thalamocortical/corticocortical network. Common histopathologic features of epilepsy of diverse and mostly focal origin are microglial activation and astrogliosis, heterotopic neurons in the white matter, loss of neurons, and the presence of inflammatory cellular infiltrates. Astrocytes exhibit smaller K+ conductances and lose gap junction coupling in many animal models as well as in sclerotic hippocampi from temporal lobe epilepsy patients. There is increasing evidence that epilepsy can be prevented or aborted in preclinical animal models of acquired epilepsy by interfering with processes that appear common to multiple acute injury etiologies, for example, in post-status epilepticus models of focal epilepsy by transient treatment with a trkB/PLCγ1 inhibitor, isoflurane, or HMGB1 antibodies and by topical administration of adenosine, in the cortical fluid percussion injury model by focal cooling, and in the albumin posttraumatic epilepsy model by losartan. Preclinical studies further highlight the roles of mTOR1 pathways, JAK-STAT3, IL-1R/TLR4 signaling, and other inflammatory pathways in the genesis or modulation of epilepsy after brain injury. The wealth of commonalities, diversity of molecular targets identified preclinically, and likely multidimensional nature of epileptogenesis argue for a combinatorial strategy in prevention therapy. Going forward, the identification of impending epilepsy biomarkers to allow better patient selection, together with better alignment with multisite preclinical trials in animal models, should guide the clinical testing of new hypotheses for epileptogenesis and its prevention.
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Affiliation(s)
- Pavel Klein
- Mid-Atlantic Epilepsy and Sleep Center, Bethesda, MD, USA
| | | | - Eleonora Aronica
- Department of (Neuro) Pathology, Academic Medical Center and Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, The Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Christophe Bernard
- Aix Marseille Univ, Inserm, INS, Instit Neurosci Syst, Marseille, 13005, France
| | - Ingmar Blümcke
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | - Detlev Boison
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR, USA
| | - Martin J Brodie
- Epilepsy Unit, West Glasgow Ambulatory Care Hospital-Yorkhill, Glasgow, UK
| | - Amy R Brooks-Kayal
- Division of Neurology, Departments of Pediatrics and Neurology, University of Colorado School of Medicine, Aurora, CO, USA
- Children's Hospital Colorado, Aurora, CO, USA
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jerome Engel
- Departments of Neurology, Neurobiology, and Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, Brain Research Institute, University of California, Los Angeles, CA, USA
| | | | | | | | | | - Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | | | - Phillip L Pearl
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Asla Pitkänen
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Noora Puhakka
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Michael A Rogawski
- Department of Neurology, University of California, Davis, Sacramento, CA, USA
| | | | - Matti Sillanpää
- Departments of Child Neurology and General Practice, University of Turku and Turku University Hospital, Turku, Finland
| | - Robert S Sloviter
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Annamaria Vezzani
- Department of Neuroscience, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Institute for Pharmacological Research, Milan,, Italy
| | - Matthew C Walker
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Hannover, Germany
- Center for Systems Neuroscience, Hannover, Germany
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Spatiotemporal propagation patterns of generalized ictal spikes in childhood absence epilepsy. Clin Neurophysiol 2017; 128:1553-1562. [PMID: 28709121 DOI: 10.1016/j.clinph.2017.05.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 04/29/2017] [Accepted: 05/31/2017] [Indexed: 11/23/2022]
Abstract
OBJECTIVE This work investigates the spatial distribution in time of generalized ictal spikes in the typical absences of childhood absence epilepsy (CAE). METHODS We studied twelve children with CAE, who had more than two typical absences during their routine video-EEG. Seizures were identified, and ictal spikes were marked over the maximum electronegative peak, clustered, waveform-averaged and spatiotemporaly analyzed in 2D electrode space. RESULTS Consistency of spatiotemporal patterns of ictal spikes was high between the absences of the same child, but low between children. Three main discharge patterns were identified: of anterio-posterior propagation, of posterio-anterior propagation and confined to the frontal/prefrontal regions. In 4 patients, the propagation patterns transformed during the seizure into either a lateralized diminished or a non-lateralized reverse direction form. Most spikes originated fronto-temporaly, all maximized over the frontal/prefrontal electrodes and mostly decayed prefrontaly. In 4 patients, lateralized propagation patterns were identified. CONCLUSIONS Ictal spike propagation patterns suggest that epileptogenic CAE networks are personalized, interconnect distal areas in the brain - not the entire cortex - with a tendency to generate bilateral symmetrical discharges, sometimes unsuccessfully. The transformation of propagation patterns during the seizure indicates the existence of dynamic interplay within epileptogenic networks. SIGNIFICANCE Our results support the revised concept of ictogenesis of ILAE definition in genetic (also known as idiopathic) generalized epilepsies. Understanding the focal features in CAE avoids misdiagnosis as focal epilepsy and inappropriate treatment.
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20
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Bagshaw AP, Hale JR, Campos BM, Rollings DT, Wilson RS, Alvim MKM, Coan AC, Cendes F. Sleep onset uncovers thalamic abnormalities in patients with idiopathic generalised epilepsy. NEUROIMAGE-CLINICAL 2017; 16:52-57. [PMID: 28752060 PMCID: PMC5519226 DOI: 10.1016/j.nicl.2017.07.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 06/29/2017] [Accepted: 07/12/2017] [Indexed: 11/16/2022]
Abstract
The thalamus is crucial for sleep regulation and the pathophysiology of idiopathic generalised epilepsy (IGE), and may serve as the underlying basis for the links between the two. We investigated this using EEG-fMRI and a specific emphasis on the role and functional connectivity (FC) of the thalamus. We defined three types of thalamic FC: thalamocortical, inter-hemispheric thalamic, and intra-hemispheric thalamic. Patients and controls differed in all three measures, and during wakefulness and sleep, indicating disorder-dependent and state-dependent modification of thalamic FC. Inter-hemispheric thalamic FC differed between patients and controls in somatosensory regions during wakefulness, and occipital regions during sleep. Intra-hemispheric thalamic FC was significantly higher in patients than controls following sleep onset, and disorder-dependent alterations to FC were seen in several thalamic regions always involving somatomotor and occipital regions. As interactions between thalamic sub-regions are indirect and mediated by the inhibitory thalamic reticular nucleus (TRN), the results suggest abnormal TRN function in patients with IGE, with a regional distribution which could suggest a link with the thalamocortical networks involved in the generation of alpha rhythms. Intra-thalamic FC could be a more widely applicable marker beyond patients with IGE. Sleep onset modifies thalamic FC in generalised epilepsy differently to controls. Differences are regionally specific. Regions connected to somatomotor/occipital cortices are consistently affected. Intra-thalamic FC may be a surrogate marker of thalamic reticular nucleus function.
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Affiliation(s)
- Andrew P Bagshaw
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK.,School of Psychology, University of Birmingham, Birmingham, UK
| | - Joanne R Hale
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK.,School of Psychology, University of Birmingham, Birmingham, UK.,Clinical Physics and Bioengineering, University Hospital Coventry and Warwickshire, Coventry, UK
| | - Brunno M Campos
- Neuroimaging Laboratory, Department of Neurology, University of Campinas, Campinas, Brazil
| | - David T Rollings
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK.,School of Psychology, University of Birmingham, Birmingham, UK.,Department of Neuroscience, Queen Elizabeth Hospital Birmingham, UK
| | - Rebecca S Wilson
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK.,School of Psychology, University of Birmingham, Birmingham, UK
| | - Marina K M Alvim
- Neuroimaging Laboratory, Department of Neurology, University of Campinas, Campinas, Brazil
| | - Ana Carolina Coan
- Neuroimaging Laboratory, Department of Neurology, University of Campinas, Campinas, Brazil
| | - Fernando Cendes
- Neuroimaging Laboratory, Department of Neurology, University of Campinas, Campinas, Brazil
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21
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Currie SP, Luz LL, Booker SA, Wyllie DJA, Kind PC, Daw MI. Reduced local input to fast-spiking interneurons in the somatosensory cortex in the GABA A γ2 R43Q mouse model of absence epilepsy. Epilepsia 2017; 58:597-607. [PMID: 28195311 PMCID: PMC5412680 DOI: 10.1111/epi.13693] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2017] [Indexed: 02/04/2023]
Abstract
Objective Absence seizures in childhood absence epilepsy are initiated in the thalamocortical (TC) system. We investigated if these seizures result from altered development of the TC system before the appearance of seizures in mice containing a point mutation in γ‐aminobutyric acid A (GABAA) receptor γ2 subunits linked to childhood absence epilepsy (R43Q). Findings from conditional mutant mice indicate that expression of normal γ2 subunits during preseizure ages protect from later seizures. This indicates that altered development in the presence of the R43Q mutation is a key contributor to the R43Q phenotype. We sought to identify the cellular processes affected by the R43Q mutation during these preseizure ages. Methods We examined landmarks of synaptic development at the end of the critical period for somatosensory TC plasticity using electrophysiologic recordings in TC brain slices from wild‐type mice and R43Q mice. Results We found that the level of TC connectivity to layer 4 (L4) principal cells and the properties of TC synapses were unaltered in R43Q mice. Furthermore, we show that, although TC feedforward inhibition and the total level of GABAergic inhibition were normal, there was a reduction in the local connectivity to cortical interneurons. This reduction leads to altered inhibition during bursts of cortical activity. Significance This altered inhibition demonstrates that alterations in cortical circuitry precede the onset of seizures by more than a week.
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Affiliation(s)
- Stephen P Currie
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Liliana L Luz
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Sam A Booker
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - David J A Wyllie
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, InStem, Bangalore, India
| | - Peter C Kind
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, InStem, Bangalore, India
| | - Michael I Daw
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
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22
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Kirazlı Ö, Çavdar S, Yıldızel S, Onat F, Kaptanoğlu E. A developmental study of glutamatergic neuron populations in the ventrobasal and the lateral geniculate nucleus of the thalamus: Comparing Genetic Absence Rats from Strasbourg (GAERS) and normal control wistar rats. Int J Dev Neurosci 2016; 56:35-41. [PMID: 27939427 DOI: 10.1016/j.ijdevneu.2016.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 12/04/2016] [Indexed: 11/28/2022] Open
Abstract
An imbalance of GABAergic inhibition and glutamatergic excitation is suspected to be the cause of absence epileptic seizures. Absence seizures are known to be generated in thalamocortical circuitry. In the present study we used light microscopy immunohistochemistry to quantify the density of glutamate+ve neurons at two developmental stages (P10 and P60) in two thalamic nuclei, the ventrobasal (VB) and lateral geniculate nucleus (LGN) in Wistar rats and compared the results with similar data obtained from genetic absence epilepsy rats from Strasbourg (GAERS). Rats were perfused transcardially with glutaraldehyde and paraformaldehyde fixative, then samples from VB and LGN were removed from each animal and sectioned. The glutamatergic neurons were labelled using light-microscopic glutamate immunohistochemistry. The disector method was used to quantify the glutamate+ve neurons in VB and LGN of GAERS and Wistar rats. The data were statistically analyzed. The distribution of the glutamate+ve neurons in the VB thalamic nucleus showed a significant reduction in the neuronal profiles per unit thalamic area from P10 to P60 in both Wistar and GAERS. The decrease was greater in the GAERS compared to the Wistar animals. However, in the LGN no reduction was observed either in the Wistar or in the GAERS. Comparing the density of glutamate+ve neurons in the VB thalamic nucleus of P10 of Wistar animals with of P10 GAERS showed statistically significant greater densities of these neurons in GAERS than in the Wistar rats. However no significant difference was present at P60 between the Wistar and GAERS animals. The disproportional decrease in GAERS may be related to the onset of absence seizures or may be related to neurogenesis of absence epilepsy.
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Affiliation(s)
- Özlem Kirazlı
- Department of Anatomy, School of Medicine, Marmara University, Istanbul, Turkey
| | - Safiye Çavdar
- Department of Anatomy, School of Medicine, Koç University, Rumelifeneri Yolu Sarıyer, Istanbul, Turkey.
| | - Sercan Yıldızel
- Department of Anatomy, School of Medicine, Marmara University, Istanbul, Turkey
| | - Filiz Onat
- Department of Pharmacology, School of Medicine, Marmara University, Istanbul, Turkey
| | - Erkan Kaptanoğlu
- Department of Neurosurgery, Marmara University, School of Medicine, Institute of Neurological Sciences, Istanbul, Turkey
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23
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Microstructural Changes in Absence Seizure Children: A Diffusion Tensor Magnetic Resonance Imaging Study. Pediatr Neonatol 2016; 57:318-25. [PMID: 26750405 DOI: 10.1016/j.pedneo.2015.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 09/22/2015] [Accepted: 10/13/2015] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Absence seizures are a subtype of epileptic seizures clinically characterized by transient alterations in states of consciousness and by electroencephalography indicating diffuse spike-wave discharges (SWD). Conventional brain magnetic resonance imaging (MRI) is not routinely used to establish the diagnosis, but rather to rule out other diseases. The present study investigated tissue integrity in children with SWD epilepsy using diffusion tensor imaging (DTI). METHODS Magnetic resonance imaging (MRI)-DTI was conducted in 18 patients with absence seizures and 10 control participants. Brain areas were evaluated using diffusion maps, and fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity (λ||), and perpendicular diffusivity (λ⊥) values were extracted and analyzed. Tractography at the regions of abnormal diffusion indices was then reconstructed in each group, and tract symmetry was evaluated by an index of asymmetry (AI). Statistical analyses were performed using nonparametric Mann-Whitney U tests, with p values < 0.05 indicating statistical significance. RESULTS Compared to the control group, patients with SWD epilepsy had lower FA values and higher MD values at the genu of the corpus callosum. There was also a stronger negative correlation between MD and FA values at the genu of the corpus callosum in patients than in control participants. The AI for the fiber tracts through the genu of the corpus callosum in the SWD group was significantly higher than that of the control group, indicating that tract distribution was more asymmetric in patients with epilepsy. There were no significant differences between groups in diffusion indices for other brain areas. CONCLUSION We observed microstructural changes in the genu of the corpus callosum, as well as reduced FA values, increased λ⊥ values, increased MD values, and asymmetric distribution of fiber tracts, indicating that DTI is more sensitive than conventional MRI to detect brain abnormalities in children with absence seizures.
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24
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Çavdar S, Özgür M, Kirazlı Ö, Karahüseyinoğlu S, Onat F. Comparing glutamatergic neuron population in the mediodorsal thalamic nucleus of genetic absence epilepsy rats from strasbourg (GAERS) and normal control Wistar rats. J Chem Neuroanat 2016; 77:93-99. [PMID: 27262783 DOI: 10.1016/j.jchemneu.2016.05.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 05/30/2016] [Accepted: 05/30/2016] [Indexed: 11/17/2022]
Abstract
An imbalance between GABAergic inhibition and glutamatergic excitation is suspected to play a role in the genesis of epileptic processes. In the present study we quantified the number of glutamate+ve neurons in the mediodorsal thalamic nucleus (MD) of genetic absence epilepsy rats from Strasbourg (GAERS) and compared these with values for normal Wistar rats. The MD thalamic nucleus was removed from each animal and the glutamatergic neurons were labelled using light-microscopy glutamate immunohistochemistry. The disector method was used to quantify the glutamate+ve neurons in the MD thalamic nucleus of GAERS and Wistar rats. The data were statistically analyzed. In the Wistar animals glutamate+ve neurons formed 89% and in GAERS 92.3% of the total neurons in 1000μm3 of MD thalamic nucleus. In GAERS glutamate+ve neurons showed statistically significant increase in the MD thalamic nucleus compared to Wistar animals. In Wistar animals the glutamate-ve neurons formed 11% and in GAERS 7.7% of the total neurons in 1000μm3 of MD thalamic. No significant difference was observed in glutamate-ve neurons between the two strains. The average diameter of glutamate+ve neurons showed no significance, while glutamate-ve neurons were significant between the two strains. The results of the present study, on genetic absence epilepsy model, GAERS, confirms the role of MD thalamic nucleus in chemically induced absence epilepsy.
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Affiliation(s)
- Safiye Çavdar
- Department of Anatomy, School of Medicine, Koç University, Sarıyer, Istanbul, Turkey.
| | - Merve Özgür
- Department of Anatomy, School of Medicine, Koç University, Sarıyer, Istanbul, Turkey
| | - Özlem Kirazlı
- Department of Anatomy, School of Medicine, Marmara University, Istanbul, Turkey
| | - Serçin Karahüseyinoğlu
- Department of Histology-Embryology, School of Medicine, Koç University, Sarıyer, Istanbul, Turkey
| | - Filiz Onat
- Department of Pharmacology and Clinic Pharmacology, School of Medicine, Marmara University, Istanbul, Turkey
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25
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The Contribution of Thalamocortical Core and Matrix Pathways to Sleep Spindles. Neural Plast 2016; 2016:3024342. [PMID: 27144033 PMCID: PMC4842069 DOI: 10.1155/2016/3024342] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/29/2016] [Indexed: 11/17/2022] Open
Abstract
Sleep spindles arise from the interaction of thalamic and cortical neurons. Neurons in the thalamic reticular nucleus (TRN) inhibit thalamocortical neurons, which in turn excite the TRN and cortical neurons. A fundamental principle of anatomical organization of the thalamocortical projections is the presence of two pathways: the diffuse matrix pathway and the spatially selective core pathway. Cortical layers are differentially targeted by these two pathways with matrix projections synapsing in superficial layers and core projections impinging on middle layers. Based on this anatomical observation, we propose that spindles can be classified into two classes, those arising from the core pathway and those arising from the matrix pathway, although this does not exclude the fact that some spindles might combine both pathways at the same time. We find evidence for this hypothesis in EEG/MEG studies, intracranial recordings, and computational models that incorporate this difference. This distinction will prove useful in accounting for the multiple functions attributed to spindles, in that spindles of different types might act on local and widespread spatial scales. Because spindle mechanisms are often hijacked in epilepsy and schizophrenia, the classification proposed in this review might provide valuable information in defining which pathways have gone awry in these neurological disorders.
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26
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Voets NL, Menke RAL, Jbabdi S, Husain M, Stacey R, Carpenter K, Adcock JE. Thalamo-Cortical Disruption Contributes to Short-Term Memory Deficits in Patients with Medial Temporal Lobe Damage. Cereb Cortex 2015; 25:4584-95. [PMID: 26009613 PMCID: PMC4816801 DOI: 10.1093/cercor/bhv109] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Short-term (STM) and long-term memory (LTM) have largely been considered as separate brain systems reflecting fronto-parietal and medial temporal lobe (MTL) functions, respectively. This functional dichotomy has been called into question by evidence of deficits on aspects of working memory in patients with MTL damage, suggesting a potentially direct hippocampal contribution to STM. As the hippocampus has direct anatomical connections with the thalamus, we tested the hypothesis that damage to thalamic nuclei regulating cortico-cortical interactions may contribute to STM deficits in patients with hippocampal dysfunction. We used diffusion-weighted magnetic resonance imaging-based tractography to identify anatomical subdivisions in patients with MTL epilepsy. From these, we measured resting-state functional connectivity with detailed cortical divisions of the frontal, temporal, and parietal lobes. Whereas thalamo-temporal functional connectivity reflected LTM performance, thalamo-prefrontal functional connectivity specifically predicted STM performance. Notably, patients with hippocampal volume loss showed thalamic volume loss, most prominent in the pulvinar region, not detected in patients with normal hippocampal volumes. Aberrant thalamo-cortical connectivity in the epileptic hemisphere was mirrored in a loss of behavioral association with STM performance specifically in patients with hippocampal atrophy. These findings identify thalamo-cortical disruption as a potential mechanism contributing to STM deficits in the context of MTL damage.
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Affiliation(s)
- Natalie L Voets
- FMRIB Centre, Nuffield Department of Clinical Neurosciences Epilepsy Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | | | - Saad Jbabdi
- FMRIB Centre, Nuffield Department of Clinical Neurosciences
| | - Masud Husain
- FMRIB Centre, Nuffield Department of Clinical Neurosciences Epilepsy Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK
| | - Richard Stacey
- Department of Neurosurgery, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | | | - Jane E Adcock
- FMRIB Centre, Nuffield Department of Clinical Neurosciences Epilepsy Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
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27
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Bertram EH. Extratemporal lobe circuits in temporal lobe epilepsy. Epilepsy Behav 2014; 38:13-8. [PMID: 25238899 DOI: 10.1016/j.yebeh.2014.07.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 07/11/2014] [Indexed: 11/26/2022]
Abstract
There is increasing interest in the functional anatomy of epilepsy with the goal to identify the critical nodes in the seizure circuits so that therapy can be directed at them. This goal is especially important because direct delivery of therapy, either through electrical stimulation, drug infusion, or molecular therapies such as optogenetics, has become increasingly possible. In this article, we will review the basic functional anatomy of mesial temporal lobe epilepsy and its primary subcortical connection, the medial dorsal nucleus of the thalamus. Based on its anatomical connections and known physiological interactions, we propose a key role for this thalamic nucleus that is essential for the development of seizures, and this role suggests that this region is a potential therapeutic target.
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Affiliation(s)
- Edward H Bertram
- Department of Neurology, University of Virginia, P.O. Box 800394, Charlottesville, VA 22908-0394, USA.
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28
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Entz L, Tóth E, Keller CJ, Bickel S, Groppe DM, Fabó D, Kozák LR, Erőss L, Ulbert I, Mehta AD. Evoked effective connectivity of the human neocortex. Hum Brain Mapp 2014; 35:5736-53. [PMID: 25044884 DOI: 10.1002/hbm.22581] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 06/04/2014] [Accepted: 06/27/2014] [Indexed: 10/25/2022] Open
Abstract
The role of cortical connectivity in brain function and pathology is increasingly being recognized. While in vivo magnetic resonance imaging studies have provided important insights into anatomical and functional connectivity, these methodologies are limited in their ability to detect electrophysiological activity and the causal relationships that underlie effective connectivity. Here, we describe results of cortico-cortical evoked potential (CCEP) mapping using single pulse electrical stimulation in 25 patients undergoing seizure monitoring with subdural electrode arrays. Mapping was performed by stimulating adjacent electrode pairs and recording CCEPs from the remainder of the electrode array. CCEPs reliably revealed functional networks and showed an inverse relationship to distance between sites. Coregistration to Brodmann areas (BA) permitted group analysis. Connections were frequently directional with 43% of early responses and 50% of late responses of connections reflecting relative dominance of incoming or outgoing connections. The most consistent connections were seen as outgoing from motor cortex, BA6-BA9, somatosensory (SS) cortex, anterior cingulate cortex, and Broca's area. Network topology revealed motor, SS, and premotor cortices along with BA9 and BA10 and language areas to serve as hubs for cortical connections. BA20 and BA39 demonstrated the most consistent dominance of outdegree connections, while BA5, BA7, auditory cortex, and anterior cingulum demonstrated relatively greater indegree. This multicenter, large-scale, directional study of local and long-range cortical connectivity using direct recordings from awake, humans will aid the interpretation of noninvasive functional connectome studies.
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Affiliation(s)
- László Entz
- Department of Neurosurgery, Hofstra North Shore LIJ School of Medicine and Feinstein Institute of Medical Research, Manhasset, New York, 11030; Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, 1132, Hungary; Department of Functional Neurosurgery and Department of Epilepsy, National Institute of Clinical Neuroscience, Budapest, 1145, Hungary; Péter Pázmány Catholic University, Faculty of Information Technology and Bionics, Budapest, 1083, Hungary
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29
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Seneviratne U, Cook M, D'Souza W. Focal abnormalities in idiopathic generalized epilepsy: A critical review of the literature. Epilepsia 2014; 55:1157-69. [DOI: 10.1111/epi.12688] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Udaya Seneviratne
- Department of Medicine; St. Vincent's Hospital; University of Melbourne; Melbourne Victoria Australia
- Department of Neuroscience; Monash Medical Centre; Melbourne Victoria Australia
| | - Mark Cook
- Department of Medicine; St. Vincent's Hospital; University of Melbourne; Melbourne Victoria Australia
| | - Wendyl D'Souza
- Department of Medicine; St. Vincent's Hospital; University of Melbourne; Melbourne Victoria Australia
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Zhang T, Zhou J, Jiang R, Yang H, Carney PR, Jiang H. Pre-seizure state identified by diffuse optical tomography. Sci Rep 2014; 4:3798. [PMID: 24445927 PMCID: PMC3896905 DOI: 10.1038/srep03798] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 12/30/2013] [Indexed: 11/23/2022] Open
Abstract
In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Here we demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking such brain activities with high spatiotemporal resolution. We detected early hemodynamic responses with heterogeneous patterns, along with intracranial electroencephalogram gamma power changes, several minutes preceding the electroencephalographic seizure onset, supporting the presence of a "pre-seizure" state. We also observed the decoupling between local hemodynamic and neural activities. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways.
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Affiliation(s)
- Tao Zhang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
| | - Junli Zhou
- Department of Pediatrics, University of Florida Gainesville, FL 32611, USA
| | - Ruixin Jiang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
| | - Hao Yang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
| | - Paul R. Carney
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
- Department of Pediatrics, University of Florida Gainesville, FL 32611, USA
- Department of Neurology, University of Florida Gainesville, FL 32611, USA
- Department of Neuroscience, University of Florida Gainesville, FL 32611, USA
| | - Huabei Jiang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
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Nadler JV, Spencer DD. What is a seizure focus? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:55-62. [PMID: 25012366 DOI: 10.1007/978-94-017-8914-1_4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The seizure focus is the site in the brain from which the seizure originated and is most likely equivalent to the epileptogenic zone, defined as the area of cerebral cortex indispensable for the generation of clinical seizures. The boundaries of this region cannot be defined at present by any diagnostic test. Imaging and EEG recording can define regions of functional deficit during the interictal period, regions that generate interictal spikes, regions responsible for the ictal symptoms, regions from which the seizure is triggered, and regions of structural damage. However, these regions define the epileptogenic zone only when they are spatially concordant. The frequent discrepancies suggest the essential involvement of synaptically connected regions, that is a distributive focus, in the origination of most seizures. Here we review supporting evidence from animal studies and studies of persons undergoing surgical resection for medically-intractable epilepsy. We conclude that very few of the common seizures are truly local, but rather depend on nodal interactions that permit spontaneous network excitability and behavioral expression. Recognition of the distributive focus underlying most seizures has motivated many surgical programs to upgrade their intracranial studies to capture activity in as much of the network as possible.
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Affiliation(s)
- J Victor Nadler
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, 3813, Durham, NC, 27710, USA,
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Bernhardt BC, Hong S, Bernasconi A, Bernasconi N. Imaging structural and functional brain networks in temporal lobe epilepsy. Front Hum Neurosci 2013; 7:624. [PMID: 24098281 PMCID: PMC3787804 DOI: 10.3389/fnhum.2013.00624] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 09/09/2013] [Indexed: 11/24/2022] Open
Abstract
Early imaging studies in temporal lobe epilepsy (TLE) focused on the search for mesial temporal sclerosis, as its surgical removal results in clinically meaningful improvement in about 70% of patients. Nevertheless, a considerable subgroup of patients continues to suffer from post-operative seizures. Although the reasons for surgical failure are not fully understood, electrophysiological and imaging data suggest that anomalies extending beyond the temporal lobe may have negative impact on outcome. This hypothesis has revived the concept of human epilepsy as a disorder of distributed brain networks. Recent methodological advances in non-invasive neuroimaging have led to quantify structural and functional networks in vivo. While structural networks can be inferred from diffusion MRI tractography and inter-regional covariance patterns of structural measures such as cortical thickness, functional connectivity is generally computed based on statistical dependencies of neurophysiological time-series, measured through functional MRI or electroencephalographic techniques. This review considers the application of advanced analytical methods in structural and functional connectivity analyses in TLE. We will specifically highlight findings from graph-theoretical analysis that allow assessing the topological organization of brain networks. These studies have provided compelling evidence that TLE is a system disorder with profound alterations in local and distributed networks. In addition, there is emerging evidence for the utility of network properties as clinical diagnostic markers. Nowadays, a network perspective is considered to be essential to the understanding of the development, progression, and management of epilepsy.
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Affiliation(s)
- Boris C Bernhardt
- Neuroimaging of Epilepsy Laboratory, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada ; Department of Social Neuroscience, Max Planck Institute for Human Cognitive and Brain Sciences Leipzig, Germany
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Russo E, Citraro R, Donato G, Camastra C, Iuliano R, Cuzzocrea S, Constanti A, De Sarro G. mTOR inhibition modulates epileptogenesis, seizures and depressive behavior in a genetic rat model of absence epilepsy. Neuropharmacology 2013; 69:25-36. [DOI: 10.1016/j.neuropharm.2012.09.019] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 09/07/2012] [Accepted: 09/29/2012] [Indexed: 12/27/2022]
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D'Amore V, Santolini I, van Rijn CM, Biagioni F, Molinaro G, Prete A, Conn PJ, Lindsley CW, Zhou Y, Vinson PN, Rodriguez AL, Jones CK, Stauffer SR, Nicoletti F, van Luijtelaar G, Ngomba RT. Potentiation of mGlu5 receptors with the novel enhancer, VU0360172, reduces spontaneous absence seizures in WAG/Rij rats. Neuropharmacology 2012; 66:330-8. [PMID: 22705340 DOI: 10.1016/j.neuropharm.2012.05.044] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 05/25/2012] [Accepted: 05/29/2012] [Indexed: 11/27/2022]
Abstract
Absence epilepsy is generated by the cortico-thalamo-cortical network, which undergoes a finely tuned regulation by metabotropic glutamate (mGlu) receptors. We have shown previously that potentiation of mGlu1 receptors reduces spontaneous occurring spike and wave discharges (SWDs) in the WAG/Rij rat model of absence epilepsy, whereas activation of mGlu2/3 and mGlu4 receptors produces the opposite effect. Here, we have extended the study to mGlu5 receptors, which are known to be highly expressed within the cortico-thalamo-cortical network. We used presymptomatic and symptomatic WAG/Rij rats and aged-matched ACI rats. WAG/Rij rats showed a reduction in the mGlu5 receptor protein levels and in the mGlu5-receptor mediated stimulation of polyphosphoinositide hydrolysis in the ventrobasal thalamus, whereas the expression of mGlu5 receptors was increased in the somatosensory cortex. Interestingly, these changes preceded the onset of the epileptic phenotype, being already visible in pre-symptomatic WAG/Rij rats. SWDs in symptomatic WAG/Rij rats were not influenced by pharmacological blockade of mGlu5 receptors with MTEP (10 or 30 mg/kg, i.p.), but were significantly decreased by mGlu5 receptor potentiation with the novel enhancer, VU0360172 (3 or 10 mg/kg, s.c.), without affecting motor behaviour. The effect of VU0360172 was prevented by co-treatment with MTEP. These findings suggest that changes in mGlu5 receptors might lie at the core of the absence-seizure prone phenotype of WAG/Rij rats, and that mGlu5 receptor enhancers are potential candidates to the treatment of absence epilepsy. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.
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Affiliation(s)
- V D'Amore
- I.R.C.C.S., NEUROMED, Neuropharmacology Unit, Parco Tecnologico, Località Camerelle 86077, Pozzilli, Isernia, Italy
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Bertram EH. Neuronal circuits in epilepsy: do they matter? Exp Neurol 2012; 244:67-74. [PMID: 22342991 DOI: 10.1016/j.expneurol.2012.01.028] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 01/27/2012] [Indexed: 12/13/2022]
Abstract
Seizures occur in groups of neurons and involve complex interactions across several regions. The focus of much epilepsy research has been on changes in single neuronal populations but the interpretation of the implications of these changes is often limited by not being able to place those observed changes appropriately in the overall function of the brain. Understanding regional interactions at the beginning and during the evolution of a seizure may help place the changes in the appropriate context of the pathophysiology of epilepsy and guide us in identifying more effective therapies. In this paper we will focus on the circuits that support the different stages of seizures. Although we are far from knowing how the system works to initiate and spread seizures, we hope to provide a framework upon which we can place cellular changes. The concepts of seizure focus, initiating seizure circuits, paths of spread and neuromodulatory centers will be used to develop a system's view of epilepsy.
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Affiliation(s)
- Edward H Bertram
- Department of Neurology, University of Virginia, P.O. Box 800394, Charlottesville, VA 22908-0394, USA.
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Chaudhary UJ, Duncan JS, Lemieux L. Mapping hemodynamic correlates of seizures using fMRI: A review. Hum Brain Mapp 2011; 34:447-66. [PMID: 22083945 DOI: 10.1002/hbm.21448] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 07/19/2011] [Accepted: 08/01/2011] [Indexed: 11/08/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) is able to detect changes in blood oxygenation level associated with neuronal activity throughout the brain. For more than a decade, fMRI alone or in combination with simultaneous EEG recording (EEG-fMRI) has been used to investigate the hemodynamic changes associated with interictal and ictal epileptic discharges. This is the first literature review to focus on the various fMRI acquisition and data analysis methods applied to map epileptic seizure-related hemodynamic changes from the first report of an fMRI scan of a seizure to the present day. Two types of data analysis approaches, based on temporal correlation and data driven, are explained and contrasted. The spatial and temporal relationship between the observed hemodynamic changes using fMRI and other non-invasive and invasive electrophysiological and imaging data is considered. We then describe the role of fMRI in localizing and exploring the networks involved in spontaneous and triggered seizure onset and propagation. We also discuss that fMRI alone and combined with EEG hold great promise in the investigation of seizure-related hemodynamic changes non-invasively in humans. We think that this will lead to significant improvements in our understanding of seizures with important consequences for the treatment of epilepsy.
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Affiliation(s)
- Umair J Chaudhary
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, WC1N 3BG, London, United Kingdom
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Sloan DM, Zhang D, Bertram EH. Excitatory amplification through divergent-convergent circuits: the role of the midline thalamus in limbic seizures. Neurobiol Dis 2011; 43:435-45. [PMID: 21554957 DOI: 10.1016/j.nbd.2011.04.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 04/10/2011] [Accepted: 04/22/2011] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION The midline thalamic nuclei are an important component of limbic seizures. Although the anatomic connections and excitatory influences of the midline thalamus are well known, its physiological role in limbic seizures is unclear. We examined the role of the midline thalamus on two circuits that are involved in limbic seizures: (a) the subiculum-prefrontal cortex (SB-PFC), and (b) the piriform cortex-entorhinal cortex (PC-EC). METHODS Evoked field potentials for both circuits were obtained in anesthetized rats, and the likely direct monosynaptic and polysynaptic contributions to the responses were identified. Seizures were generated in both circuits by 20 Hz stimulus trains. Once stable seizures and evoked potentials were established, the midline thalamus was inactivated through an injection of the sodium channel blocker tetrodotoxin (TTX), and the effects on the evoked responses and seizures were analyzed. RESULTS Inactivation of the midline thalamus suppressed seizures in both circuits. Seizure suppression was associated with a significant reduction in the late thalamic component but no significant change in the early direct monosynaptic component. Injections that did not suppress the seizures did not alter the evoked potentials. CONCLUSIONS Suppression of the late thalamic component of the evoked potential at the time of seizure suppression suggests that the thalamus facilitates seizure induction by extending the duration of excitatory drive through a divergent-convergent excitatory amplification system. This work may have broader implications for understanding signaling in the limbic system.
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Affiliation(s)
- David M Sloan
- University of Virginia, Neuroscience Graduate Program, Charlottesville 22901, USA
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Akakin D, Sirvanci S, Gurbanova A, Aker R, Onat F, San T. Ultrastructural GABA immunocytochemistry in the mossy fiber terminals of Wistar and genetic absence epileptic rats receiving amygdaloid kindling stimulations. Brain Res 2010; 1377:101-8. [PMID: 21195064 DOI: 10.1016/j.brainres.2010.12.066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 12/20/2010] [Accepted: 12/21/2010] [Indexed: 10/18/2022]
Abstract
The existence of absence epilepsy and temporal lobe epilepsy in the same patient is not common in clinical practice. The reason why both types of seizures are rarely seen in the same patient is not well understood. Therefore, we aimed to investigate kindling in a well known model of human absence epilepsy, genetic absence epilepsy rats from Strasbourg (GAERS). In the present study, we analyzed whether the GABA content of GAERS that received kindling stimulations was altered in the hippocampal mossy fiber terminals compared to non-epileptic control (NEC) Wistar rats. For this purpose, we used an immunocytochemical technique at the ultrastructural level. Ultrathin sections were immunolabeled with anti-GABA antibody and transmission electron microscopy was used for the ultrastructural examination. The number of gold particles per nerve terminal was counted and the area of the nerve terminal was determined using NIH image analysis program. The GABA density was found to be higher in sham-operated GAERS than sham-operated Wistar rats. The density was increased in kindling Wistar group compared to sham-operated Wistar and kindling GAERS groups. No statistical difference was observed between sham-operated GAERS and kindling GAERS groups. The increase in GABA levels in stimulated Wistar rats may be a result of a protective mechanism. Furthermore, there may be strain differences between Wistar rats and GAERS and our findings addressing different epileptogenesis mechanisms in these strains might be a basis for future experimental studies.
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Affiliation(s)
- Dilek Akakin
- Department of Histology and Embryology, Faculty of Medicine, Marmara University, Istanbul, Turkey.
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Adams BEL, Kyi M, Reid CA, Myers DE, Xu S, Williams DA, O'Brien TJ. Seizure-like thalamocortical rhythms initiate in the deep layers of the cortex in a co-culture model. Exp Neurol 2010; 227:203-9. [PMID: 21075104 DOI: 10.1016/j.expneurol.2010.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 09/16/2010] [Accepted: 11/04/2010] [Indexed: 01/03/2023]
Abstract
The oscillatory rhythms underlying many physiological and pathological states, including absence seizures, require both the thalamus and cortices for full expression. A co-culture preparation combining cortical and thalamic explants provides a unique model for investigating how such oscillations initiate and spread. Here we investigated the dynamics of synchronized thalamocortical activity by simultaneous measurement of field-potential recordings and rapid imaging of Ca(2+) transients by fluorescence methods. Spontaneous sustained hypersynchronized "seizure-like" oscillations required reciprocal cortico-thalamocortical connections. Isolated cortical explants can independently develop brief discharges, while thalamic explants alone were unable to do so. Rapid imaging of Ca(2+) transients demonstrated deep-layer cortical initiation of oscillatory network activity in both connected and isolated explants. Further, cortical explants derived from a rat model of genetic absence epilepsy showed increased bursting duration consistent with an excitable cortex. We propose that thalamocortical oscillatory network activity initiates in deep layers of the cortex with reciprocal thalamic interconnections enabling sustained hyper-synchronization.
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Affiliation(s)
- Brendan E L Adams
- Department of Physiology, Centre for Neuroscience and Medicine (RMH/WH), The University of Melbourne, Melbourne, Victoria 3010, Australia
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Abstract
Generalized-Onset Seizures with Secondary Focal Evolution. Williamson R, Hanif S, Mathews GC, Lagrange AH, Abou-Khalil B. Epilepsia 2009;50(7):1827–1832. The international seizure classification recognizes that partial-onset seizures can become secondarily generalized, but generalized-onset seizures are expected to remain generalized. We report six patients who had recorded seizures with generalized onset, but subsequent evolution into a focal discharge. The clinical seizure onset was generalized absence or myoclonic, and the most common subsequent clinical pattern was prolonged behavioral arrest with mild automatisms, and then postictal confusion. The ictal discharge started with generalized spike-and-wave activity and then acquired a focal predominance. Interictal epileptiform activity was generalized. There were no focal magnetic resonance imaging abnormalities. Four patients were misdiagnosed with complex partial seizures. All patients were initially refractory, but three became seizure-free and three improved after treatment with antiepileptic medications appropriate for absence or myoclonic seizures. Generalized-onset seizures that acquire focal features are easily misdiagnosed as complex partial. These seizures have a more favorable response to medications effective against generalized absence and myoclonic seizures.
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Moeller F, Siebner HR, Ahlgrimm N, Wolff S, Muhle H, Granert O, Boor R, Jansen O, Gotman J, Stephani U, Siniatchkin M. fMRI activation during spike and wave discharges evoked by photic stimulation. Neuroimage 2009; 48:682-95. [DOI: 10.1016/j.neuroimage.2009.07.019] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 07/09/2009] [Accepted: 07/10/2009] [Indexed: 11/29/2022] Open
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Tezer FI, Saygi S. Unilateral thalamic lesions and generalized or lateralized spike wave discharges. Epilepsy Res 2009; 86:228-31. [PMID: 19577434 DOI: 10.1016/j.eplepsyres.2009.05.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2009] [Revised: 05/27/2009] [Accepted: 05/31/2009] [Indexed: 12/26/2022]
Abstract
We report four adult patients who had thalamic lesions and lateralized or generalized spike wave discharges (SWDs). The first two patients also had cortical lesions. The role of the cortex and thalamus in the generation of SWDs is discussed. The third patient had a history of idiopathic generalized epilepsy (IGE) with intractable seizures. The last patient had partial seizures and absences. The coexistence of IGE with refractory focal epilepsy and the relation with thalamic lesions are discussed.
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Affiliation(s)
- F Irsel Tezer
- Institue of Neurological Sciences and Psychiatry, Hacettepe University, School of Medicine, Ankara, Turkey.
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Bernhardt BC, Rozen DA, Worsley KJ, Evans AC, Bernasconi N, Bernasconi A. Thalamo–cortical network pathology in idiopathic generalized epilepsy: Insights from MRI-based morphometric correlation analysis. Neuroimage 2009; 46:373-81. [DOI: 10.1016/j.neuroimage.2009.01.055] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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DTI abnormalities in anterior corpus callosum of rats with spike-wave epilepsy. Neuroimage 2009; 47:459-66. [PMID: 19398019 DOI: 10.1016/j.neuroimage.2009.04.060] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 04/08/2009] [Accepted: 04/15/2009] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVE Absence epilepsy is a common seizure disorder in children which can produce chronic psychosocial sequelae. Human patients and rat absence models show bilateral spike-wave discharges (SWD) in cortical regions. We employed diffusion tensor imaging (DTI) in rat absence models to detect abnormalities in white matter pathways connecting regions of seizure activity. METHODS We studied Wistar albino Glaxo rats of Rijswijk (WAG/Rij), genetic absence epilepsy rats of Strasbourg (GAERS), and corresponding nonepileptic control strains. Ex vivo DTI was performed at 9.4 T with diffusion gradients applied in 16 orientations. We compared fractional anisotropy (FA), perpendicular (lambda(perpendicular)) and parallel (lambda(||)) diffusivity between groups using t-maps and region of interest (ROI) measurements. RESULTS Adult epileptic WAG/Rij rats exhibited a localized decrease in FA in the anterior corpus callosum. This area was confirmed by tractography to interconnect somatosensory cortex regions most intensely involved in seizures. This FA decrease was not present in young WAG/Rij rats before onset of SWD. GAERS, which have more severe SWD than WAG/Rij, exhibited even more pronounced callosal FA decreases. Reduced FA in the epileptic animals originated from an increased lambda(perpendicular) with no significant changes in lambda(||). INTERPRETATION Reduced FA with increased lambda(perpendicular) suggests that chronic seizures cause reduction in myelin or decreased axon fiber density in white matter pathways connecting regions of seizure activity. These DTI abnormalities may improve the understanding of chronic neurological difficulties in children suffering with absence epilepsy, and may also serve as a noninvasive biomarker for monitoring beneficial effects of treatment.
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Badawy RAB, Harvey AS, Macdonell RAL. Cortical hyperexcitability and epileptogenesis: Understanding the mechanisms of epilepsy - part 2. J Clin Neurosci 2009; 16:485-500. [PMID: 19230676 DOI: 10.1016/j.jocn.2008.10.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 10/03/2008] [Indexed: 12/19/2022]
Abstract
Epilepsy encompasses a diverse group of seizure disorders caused by a variety of structural, cellular and molecular alterations of the brain primarily affecting the cerebral cortex, leading to recurrent unprovoked epileptic seizures. In this two-part review we examine the mechanisms underlying normal neuronal function and those predisposing to recurrent epileptic seizures starting at the most basic cellular derangements (Part 1, Volume 16, Issue 3) and working up to the highly complex epileptic networks and factors that modulate the predisposition to seizures (Part 2). We attempt to show that multiple factors can modify the epileptic process and that different mechanisms underlie different types of epilepsy, and in most situations there is an interplay between multiple genetic and environmental factors.
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Affiliation(s)
- Radwa A B Badawy
- Department of Neurology, Austin Health, Heidelberg, Victoria, Australia
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Englot DJ, Blumenfeld H. Consciousness and epilepsy: why are complex-partial seizures complex? PROGRESS IN BRAIN RESEARCH 2009; 177:147-70. [PMID: 19818900 DOI: 10.1016/s0079-6123(09)17711-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Why do complex-partial seizures in temporal lobe epilepsy (TLE) cause a loss of consciousness? Abnormal function of the medial temporal lobe is expected to cause memory loss, but it is unclear why profoundly impaired consciousness is so common in temporal lobe seizures. Recent exciting advances in behavioral, electrophysiological, and neuroimaging techniques spanning both human patients and animal models may allow new insights into this old question. While behavioral automatisms are often associated with diminished consciousness during temporal lobe seizures, impaired consciousness without ictal motor activity has also been described. Some have argued that electrographic lateralization of seizure activity to the left temporal lobe is most likely to cause impaired consciousness, but the evidence remains equivocal. Other data correlates ictal consciousness in TLE with bilateral temporal lobe involvement of seizure spiking. Nevertheless, it remains unclear why bilateral temporal seizures should impair responsiveness. Recent evidence has shown that impaired consciousness during temporal lobe seizures is correlated with large-amplitude slow EEG activity and neuroimaging signal decreases in the frontal and parietal association cortices. This abnormal decreased function in the neocortex contrasts with fast polyspike activity and elevated cerebral blood flow in limbic and other subcortical structures ictally. Our laboratory has thus proposed the "network inhibition hypothesis," in which seizure activity propagates to subcortical regions necessary for cortical activation, allowing the cortex to descend into an inhibited state of unconsciousness during complex-partial temporal lobe seizures. Supporting this hypothesis, recent rat studies during partial limbic seizures have shown that behavioral arrest is associated with frontal cortical slow waves, decreased neuronal firing, and hypometabolism. Animal studies further demonstrate that cortical deactivation and behavioral changes depend on seizure spread to subcortical structures including the lateral septum. Understanding the contributions of network inhibition to impaired consciousness in TLE is an important goal, as recurrent limbic seizures often result in cortical dysfunction during and between epileptic events that adversely affects patients' quality of life.
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Affiliation(s)
- Dario J Englot
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
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Bertram EH. Temporal lobe epilepsy: where do the seizures really begin? Epilepsy Behav 2009; 14 Suppl 1:32-7. [PMID: 18848643 PMCID: PMC2913468 DOI: 10.1016/j.yebeh.2008.09.017] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Accepted: 09/16/2008] [Indexed: 11/26/2022]
Abstract
Defining precisely the site of seizure onset has important implications for our understanding of the pathophysiology of temporal lobe epilepsy, as well as for the surgical treatment of the disorder. Removal of the limbic areas of the medial temporal lobe has led to a high rate of seizure control, but the relatively large number of patients for whom seizure control is incomplete, as well as the low rate of surgical cure, suggests that the focus extends beyond the usual limits of surgical resection. Reevaluation of the extent of the pathology, as well as new data from animal models, suggests that the seizure focus extends, at least in some cases, beyond the hippocampus and amygdala, which are usually removed at the time of surgery. In this review, we examine current information about the pathology and physiology of mesial temporal lobe epilepsy syndrome, with special emphasis on the distribution of the changes and patterns of seizure onset. We then propose a hypothesis for the nature of the seizure focus in this disorder and discuss its clinical implications, with the ultimate goal of improving surgical outcomes and developing nonsurgical therapies that may improve seizure control.
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Affiliation(s)
- Edward H. Bertram
- Department of Neurology, University of Virginia, Charlottesville, Virginia, USA
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48
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Vinogradova LV. Audiogenic kindling in Wistar and WAG/Rij rats: Kindling-prone and kindling-resistant subpopulations. Epilepsia 2008; 49:1665-74. [DOI: 10.1111/j.1528-1167.2008.01617.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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49
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Bertram EH, Zhang D, Williamson JM. Multiple roles of midline dorsal thalamic nuclei in induction and spread of limbic seizures. Epilepsia 2007; 49:256-68. [PMID: 18028408 DOI: 10.1111/j.1528-1167.2007.01408.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE Studies have suggested that the medial dorsal nucleus of the thalamus plays a role in the behavioral expression of limbic seizures, but it is unclear whether this region is a key component for the primary seizure circuitry or a path for seizure spread from one region to another. This study was undertaken to determine the potential role of this region in limbic seizure activity. METHODS Adult male rats received kindling stimulation either under urethane anesthesia or while awake. Glutamate or its agonists or the GABA antagonist bicuculline or agonist muscimol were infused into the medial dorsal nucleus. In another series, kindling acquisition was compared among three thalamic sites as well as with the amygdala and hippocampus RESULTS Drugs that enhanced excitatory drive or blocked GABA resulted in significant prolongation of electrographic seizure activity compared to saline infused controls. Enhanced GABA activity resulted in a significant reduction of seizure duration. Infusion of the compounds lateral to the medial dorsal nucleus did not affect seizure duration. In the kindling studies the medial dorsal region is the only thalamic nucleus from which hippocampal seizures can be induced, but with an elevated afterdischarge threshold compared to the two limbic sites. However, the seizures generalized more rapidly from the medial dorsal region. CONCLUSIONS This study demonstrates that the medial dorsal nucleus and other dorsal midline nuclei have a significant role in the primary seizure circuits of limbic seizures as well as in spread of seizure activity to other regions.
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Affiliation(s)
- Edward H Bertram
- Department of Neurology, University of Virginia, Charlottesville, Virginia 22908-0394, U.S.A.
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Abstract
Ethosuximide, 2-ethyl-2-methylsuccinimide, has been used extensively for "petit mal" seizures and it is a valuable agent in studies of absence epilepsy. In the treatment of epilepsy, ethosuximide has a narrow therapeutic profile. It is the drug of choice in the monotherapy or combination therapy of children with generalized absence (petit mal) epilepsy. Commonly observed side effects of ethosuximide are dose dependent and involve the gastrointestinal tract and central nervous system. Ethosuximide has been associated with a wide variety of idiosyncratic reactions and with hematopoietic adverse effects. Typical absence seizures are generated as a result of complex interactions between the thalamus and the cerebral cortex. This thalamocortical circuitry is under the control of several specific inhibitory and excitatory systems arising from the forebrain and brainstem. Corticothalamic rhythms are believed to be involved in the generation of spike-and-wave discharges that are the characteristic electroencephalographic signs of absence seizures. The spontaneous pacemaker oscillatory activity of thalamocortical circuitry involves low threshold T-type Ca2+ currents in the thalamus, and ethosuximide is presumed to reduce these low threshold T-type Ca2+ currents in thalamic neurons. Ethosuximide also decreases the persistent Na+ and Ca2+ -activated K+ currents in thalamic and layer V cortical pyramidal neurons. In addition, there is evidence that in a genetic absence epilepsy rat model ethosuximide reduces cortical gamma-aminobutyric acid (GABA) levels. Also, elevated glutamate levels in the primary motor cortex of rats with absence epilepsy (but not in normal animals) are reduced by ethosuximide.
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Affiliation(s)
- M Zafer Gören
- Department of Pharmacology and Clinical Pharmacology, School of Medicine, Epilepsy Research Center, Marmara University, Haydarpaşa, Istanbul, Turkey.
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