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    Time-dependent evolution of seizures in a model of mesial temporal lobe epilepsy.
    Neurobiol Dis 2017 Oct 12;106:205-213. Epub 2017 Jul 12.
    Montreal Neurological Institute, Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC H3A 2B4, Canada; Montreal Neurological Institute, Department Physiology, McGill University, 3801 University Street, Montréal, QC H3A 2B4, Canada. Electronic address:
    Low-voltage fast (LVF) and hypersynchronous (HYP) - onset seizures occur in the EEG obtained with depth electrodes from mesial temporal lobe epilepsy (MTLE) patients and animal models. In epileptic rats analyzed up to approximately two weeks after pilocarpine-induced status epilepticus (SE), these patterns are associated with specific high-frequency oscillation (HFO) content: ripples (80-200Hz) or fast-ripples (250-500Hz) predominate in LVF or HYP seizures, respectively. To establish whether these features change over the course of the disease, we recorded the EEG from the hippocampal CA3 subfield, subiculum, entorhinal cortex and dentate gyrus in two groups of pilocarpine-treated rats: the "early stage group" (n=8) was analyzed from day 3 to 20 post-SE while the "late stage group" (n=7) was studied from day 27 to 53 post-SE. We found that: (i) HYP and LVF seizures prevail in the early and late stage group, respectively; (ii) HYP seizures mainly originate from CA3 in the early stage group only; (iii) LVF seizures in both early and late stage group originate from a diffuse network; (iv) LVF and HYP seizures in the early stage group are mainly associated with ripples and fast ripples, respectively; but (v) fast ripples predominate in the late stage group, regardless of seizure onset pattern. Finally, extensive neuronal loss occurred in the hippocampus of the late stage group. Our results reveal that significant changes in ictogenesis and HFO occurrence, which are associated with the manifestation of severe hippocampal damage, occur over time in this MTLE model.

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    Montreal Neurological Institute and Department of Neurology and Neurosurgery, McGill University, Montréal, Quebec, Canada H3A 2B4.
    High-frequency oscillations (HFOs; 80-500 Hz) are thought to mirror the pathophysiological changes occurring in epileptic brains. However, the distribution of HFOs during seizures remains undefined. Here, we recorded from the hippocampal CA3 subfield, subiculum, entorhinal cortex, and dentate gyrus to quantify the occurrence of ripples (80-200 Hz) and fast ripples (250-500 Hz) during low-voltage fast-onset (LVF) and hypersynchronous-onset (HYP) seizures in the rat pilocarpine model of temporal lobe epilepsy. Read More
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    Epilepsy Res 2015 Sep 19;115:8-16. Epub 2015 May 19.
    Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, Canada H3A 2B4. Electronic address:
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    Exp Neurol 2016 Oct 22;284(Pt A):29-37. Epub 2016 Jul 22.
    Department of Pharmacology, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Zhejiang University, Hangzhou, China; Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China. Electronic address:
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    Montreal Neurological Institute and Departments of Neurology and Neurosurgery and of Physiology, McGill University, Montréal, Canada
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