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Document Type:Latin Dissertation
Language of Document:English
Record Number:53009
Doc. No:TL22963
Call number:‭NR12018‬
Main Entry:Seyed Mohammad Mirsattari
Title & Author:Hemodynamic and metabolic alterations during interictal epileptic discharges in an animal model of occipital epilepsySeyed Mohammad Mirsattari
College:The University of Western Ontario (Canada)
Date:2005
Degree:Ph.D.
student score:2005
Page No:188
Abstract:Epileptic disorders manifest with seizures and interictal epileptiform discharges (IEDs). The hemodynamic and metabolic changes that accompany IEDs may be critical for epileptogenesis but they are poorly understood. This thesis aims to characterize such changes. Given the unpredictable occurrence of IEDs in human subjects, an animal model with reproducible stereotyped IEDs was achieved by focal injection of penicillin into the occipital cortex of rats anesthetized with isoflurane. Simultaneous electroencephalogram (EEG)-functional magnetic resonance imaging (IMRI) was used to study the hemodynamic changes during IEDs while short echo-time proton magnetic resonance spectroscopy ( 1H MRS) was used to measure changes in total glutamate, glutamine and γ-aminobutyric acid (GABA) levels of the epileptic focus during IEDs. To achieve and maintain a physiologically stable state in rats in the MRI environment, a minimally invasive but comprehensive system was developed to monitor and maintain body temperature, heart rate, blood pressure, blood oxygen saturation and end-tidal CO2. Real-time display of artifact-free EEG recording during fMRI/MRS studies was accomplished by maximizing common mode rejection of EEG display channels during fMRI/MRS. IEDs were shown to be stable for long periods of time and background EEG activity was partly suppressed by isoflurane anesthesia. Artifact suppression efficiency of 70%-100% was achieved following direct subtraction of referentially recorded filtered EEG tracings from active electrodes, which were located in close proximity to each other (over homologous occipital cortices) and a reference electrode. Two independent post-acquisition processing tools, independent component analysis (ICA) and direct subtraction of unfiltered digital EEG data in MATLAB, were used to verify the accuracy of real-time EEG display. Using simultaneous temporal ICA of EEG and spatial ICA of Echo Planar Imaging data in this animal model, I demonstrated a significant correlation between Blood Oxygenation Level-Dependent fMRI signals and IEDs, suggesting that the neurovascular coupling is maintained during IEDs. In separate experiments, single voxel 1H MRS revealed that penicillin injection in the occipital cortex resulted in time-dependent changes in glutamate, glutamine and GABA levels at the epileptic focus. (Abstract shortened by UMI.)
Subject:Biological sciences; Epilepsy; Interictal epileptic discharges; Occipital epilepsy; Neurology; 0317:Neurology
Added Entry:The University of Western Ontario (Canada)