Optical Imaging Reveals Characteristic Seizure Onsets, Spread Patterns, and Propagation Velocities in Hippocampal–Entorhinal Cortex Slices of Juvenile Rats

Weißinger, Florian; Buchheim, Katharina; Siegmund, Herbert; Heinemann, Uwe; Meierkord, Hartmut

doi:10.1006/nbdi.2000.0298

Cited by 54 publications

(43 citation statements)

References 36 publications

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“…Previous studies indicate that the origin of seizure-like activity onset may depend on the postnatal age [16]. Our experiments reveal that both CA1 and CA3 regions in VH are able to produce the EA in response to the Mg 2+ -free solution.…”

Section: Resultssupporting

confidence: 55%

Effect of altered extracellular magnesium concentration on the neuronal activity in different hippocampal regions of immature rats

Власюк¹,

Romanov²,

Isaev³

et al. 2017

Fiziol Zh

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Section: Resultssupporting

confidence: 55%

Effect of altered extracellular magnesium concentration on the neuronal activity in different hippocampal regions of immature rats

Власюк¹,

Romanov²,

Isaev³

et al. 2017

Fiziol Zh

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“…Measurements of intrinsic optical signal during epileptic activity in slices suggests a time-dependent shrinkage of the extracellular space fraction (Andrew and MacVicar 1994;Buchheim et al 2000;Hochman et al 1995), although the relationship between intrinsic optical signal and extracellular space can be inconsistent and can depend on recording conditions (Buchheim et al 1999). Any shrinkage of the extracellular space might be expected to modify the strength of field effects between neurons (Ballyk et al 1991;Dudek et al 1986).…”

Section: Introductionmentioning

confidence: 99%

Tissue Resistance Changes and the Profile of Synchronized Neuronal Activity During Ictal Events in the Low-Calcium Model of Epilepsy

Fox

Bikson²,

Jefferys

2004

Journal of Neurophysiology

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Fox, John E., Marom Bikson, and John G. R. Jefferys. Tissue resistance changes and the profile of synchronized neuronal activity during ictal events in the low-calcium model of epilepsy. J Neurophysiol 92: 181-188, 2004. First published March 3, 2004 10.1152/ jn.00123.2004. Population spikes vary in size during prolonged epileptic ("ictal") discharges, indicating variations in neuronal synchronization. Here we investigate the role of changes in tissue electrical resistivity in this process. We used the rat hippocampal slice, lowCa 2ϩ model of epilepsy and measured changes in pyramidal layer extracellular resistance during the course of electrographic seizures. During each burst, population spike frequency decreased, whereas amplitude and spatial synchronization increased; after the main discharge, there could be brief secondary discharges that, in contrast with those in the primary discharge, started with high-amplitude population spikes. Mean resistivity increased from 1,231 ⍀.cm immediately before the burst to a maximum of 1,507 ⍀.cm during the burst. There was no significant increase during the first 0.5-1 s of the field burst, but resistance then increased ( ϳ 5 s), reaching its peak at the end of the burst, and then decayed slowly ( ϳ 10 s). In further experiments, we modulated the efficacy of electrical field effects by changing perfusate osmolarity. Reducing osmolarity by 40 -70 mOsm increased preburst resistivity by 19%; it reduced minimum population spike frequency (ϫ0.6 -0.7) and increased both maximum population spike amplitude (ϫ1.5-2.3) and spatial synchronization (ϫ1.4 -2.5, crosscorrelation over 0.5 mm) during bursts. Increasing osmolarity by 20 -40 mOsm had the opposite effects. These results suggest that, during each field burst, field effects between neurons gradually become more effective as cells swell, thereby modulating burst dynamics and facilitating the rapid synchronization of secondary discharges.

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“…In published studies to date, diffuse reflectance optical imaging has been used frequently to monitor the hemodynamics of an epileptic lesion in vivo in both animal models of epilepsy and humans. 3,8,14,17,28,37,40,41,44,49,52,53 Although these results support the idea that the investigation of intrinsic physiological characteristics, especially hemodynamics, may be a viable alternative or addition to the current methods of epileptic lesion demarcation, the impact of such an approach on the outcome of epilepsy surgery has not yet been determined. Furthermore, the feasibility of using optical spectroscopy to delineate the margins of neocortical epileptic lesions in children has not yet been proven.…”

Section: Optical Spectroscopymentioning

confidence: 77%

“…The fluorescence and diffuse reflectance spectral features depict unique, static, in vivo characteristics of the epileptic cortex during the interictal period, which should not be confused with the dynamic diffuse reflectance features reported by other groups. 3,8,14,17,28,37,40,41,44,49,52,53 These observations warrant further studies to ascertain the clinical utility of optical spectroscopy in pediatric epilepsy surgery.…”

Section: Discussionmentioning

confidence: 89%

“…In other words, they provide only a snapshot of the physiological characteristics of the cortex during a 1-second integration time. The dynamic nature of brain metabolism and hemodynamics 3,8,14,17,28,37,40,41,44,49,52,53 is completely neglected in this statistical model. To address this potential shortcoming, we have designed and developed a new spectroscopic system that can be used to acquire broadband optical spectra (400-950 nm) from the brain at a rate of 33 Hz in a continuous manner.…”

Section: Neurosurg Focus / Volume 25 / September 2008mentioning

confidence: 99%

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The role of optical spectroscopy in epilepsy surgery in children

Bhatia

Ragheb

Johnson

et al. 2008

FOC

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Object Surgery is an important therapeutic modality for pediatric patients with intractable epilepsy. However, existing imaging and diagnostic technologies such as MR imaging and electrocochleography (ECoG) do not always effectively delineate the true resection margin of an epileptic cortical lesion because of limitations in their sensitivity. Optical spectroscopic techniques such as fluorescence and diffuse reflectance spectroscopy provide a nondestructive means of gauging the physiological features of the brain in vivo, including hemodynamics and metabolism. In this study, the authors investigate the feasibility of using combined fluorescence and diffuse reflectance spectroscopy to assist epilepsy surgery in children. Methods In vivo static fluorescence and diffuse reflectance spectra were acquired from the brain in children undergoing epilepsy surgery. Spectral measurements were obtained using a portable spectroscopic system in conjunction with a fiber optic probe. The optical investigations were conducted at the normal and abnormal cortex as defined by intraoperative ECoG and preoperative imaging studies. Biopsy samples were taken from the investigated sites located within the zone of resection. The optical spectra were classified into multiple subsets in accordance with the ECoG and histological study results. The authors used statistical comparisons between 2 given data subsets to identify unique spectral features. Empirical discrimination algorithms were developed using the identified spectral features to determine if the objective of the study was achieved. Results Fifteen pediatric patients were enrolled in this pilot study. Elevated diffuse reflectance signals between 500 and 600 nm and/or between 650 and 850 nm were observed commonly in the investigated sites with abnormal ECoG and/or histological features in 10 patients. The appearance of a fluorescent peak at 400 nm was observed in both normal and abnormal cortex of 5 patients. These spectral alterations were attributed to changes in morphological and/or biochemical characteristics of the epileptic cortex. The sensitivities and specificities of the empirical discrimination algorithms, which were constructed using the identified spectral features, were all > 90%. Conclusions The results of this study demonstrate the feasibility of using static fluorescence and diffuse reflectance spectroscopy to differentiate normal from abnormal cortex on the basis of intraoperative assessment of ECoG and histological features. It is therefore possible to use fluorescence and diffuse reflectance spectroscopy as an aid in epilepsy surgery.

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Optical Imaging Reveals Characteristic Seizure Onsets, Spread Patterns, and Propagation Velocities in Hippocampal–Entorhinal Cortex Slices of Juvenile Rats

Cited by 54 publications

References 36 publications

Effect of altered extracellular magnesium concentration on the neuronal activity in different hippocampal regions of immature rats

Effect of altered extracellular magnesium concentration on the neuronal activity in different hippocampal regions of immature rats

Tissue Resistance Changes and the Profile of Synchronized Neuronal Activity During Ictal Events in the Low-Calcium Model of Epilepsy

The role of optical spectroscopy in epilepsy surgery in children

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