scholarly journals Intracranial EEG Biomarkers for Seizure Lateralization in Rapidly-Bisynchronous Epilepsy After Laser Corpus Callosotomy

2021 ◽  
Vol 12 ◽  
Author(s):  
Simon Khuvis ◽  
Sean T. Hwang ◽  
Ashesh D. Mehta
Keyword(s):  
High Frequency ◽  
Detection Threshold ◽  
Low Frequency ◽  
Ground Truth ◽  
Line Length ◽  
High Frequency Oscillation ◽  
Corpus Callosotomy ◽  
Intracranial Eeg ◽  
Interictal Epileptiform Discharge ◽  
High Gamma

Objective: It has been asserted that high-frequency analysis of intracranial EEG (iEEG) data may yield information useful in localizing epileptogenic foci.Methods: We tested whether proposed biomarkers could predict lateralization based on iEEG data collected prior to corpus callosotomy (CC) in three patients with bisynchronous epilepsy, whose seizures lateralized definitively post-CC. Lateralization data derived from algorithmically-computed ictal phase-locked high gamma (PLHG), high gamma amplitude (HGA), and low-frequency (filtered) line length (LFLL), as well as interictal high-frequency oscillation (HFO) and interictal epileptiform discharge (IED) rate metrics were compared against ground-truth lateralization from post-CC ictal iEEG.Results: Pre-CC unilateral IEDs were more frequent on the more-pathologic side in all subjects. HFO rate predicted lateralization in one subject, but was sensitive to detection threshold. On pre-CC data, no ictal metric showed better predictive power than any other. All post-corpus callosotomy seizures lateralized to the pathological hemisphere using PLHG, HGA, and LFLL metrics.Conclusions: While quantitative metrics of IED rate and ictal HGA, PHLG, and LFLL all accurately lateralize based on post-CC iEEG, only IED rate consistently did so based on pre-CC data.Significance: Quantitative analysis of IEDs may be useful in lateralizing seizure pathology. More work is needed to develop reliable techniques for high-frequency iEEG analysis.

scholarly journals Intracranial EEG biomarkers for seizure lateralization in rapidly-bisynchronous epilepsy after laser corpus callosotomy.

2020 ◽  
Author(s):  
Simon Khuvis ◽  
Sean T Hwang ◽  
Ashesh D Mehta
Keyword(s):  
High Frequency ◽  
Detection Threshold ◽  
Ground Truth ◽  
Line Length ◽  
High Frequency Oscillation ◽  
Corpus Callosotomy ◽  
Intracranial Eeg ◽  
Yield Information ◽  
Interictal Epileptiform Discharge ◽  
High Gamma

Objective: It has been asserted that high-frequency analysis of intracranial EEG (iEEG) data may yield information useful in localizing epileptogenic foci. Methods: We tested whether proposed biomarkers could predict lateralization based on iEEG data collected prior to corpus callostomy (CC) in patients with bisynchronous epilepsy, whose seizures lateralized definitively post-CC. Lateralization data derived from algorithmically-computed ictal phase-locked high gamma (PLHG), high gamma amplitude (HGA) and line length (LL), as well as interictal high-frequency oscillation (HFO) and interictal epileptiform discharge (IED) rate metrics were compared against ground-truth lateralization from post-CC ictal iEEG. Results: Pre-CC unilateral IEDs were more frequent on the more-pathologic side in all subjects. HFO rate predicted lateralization in one subject, but was sensitive to detection threshold. On pre-CC data, no ictal metric showed better predictive power than any other. All post-corpus callosotomy seizures lateralized to the pathological hemisphere using PLHG, HGA and LL metrics. Conclusions: While quantitative metrics of IED rate and ictal HGA, PHLG and LL all accurately lateralize based on post-CC iEEG, only IED rate consistently does so based on pre-CC data. Significance: Quantitative analysis of IEDs may be useful in localizing seizure pathology. More work is needed to develop reliable techniques for high-frequency iEEG analysis.

Analysis of Fast-Scale Bifurcation in Peak Current Controlled Buck-Boost Inverter Based on Unified Averaged Model

2016 ◽  
Vol 26 (05) ◽  
pp. 1650074 ◽  
Author(s):  
Hao Zhang ◽  
Shuai Dong ◽  
Weimin Guan ◽  
Ye Liu
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Period Doubling ◽  
Current Control ◽  
High Frequency Oscillation ◽  
Switching Frequency ◽  
Unified Framework ◽  
Frequency Oscillation ◽  
Peak Current ◽  
Averaged Model

In this paper, a unified averaged modeling method is proposed to investigate the fast-scale period-doubling bifurcation of a full-bridge integrated buck-boost inverter with peak current control. In order to increase the resolution of the conventional classic averaged model to half the switching frequency, sample-and-hold effect of inductor current is absorbed into the averaged model, i.e. the proposed unified averaged model can capture the high-frequency dynamical characteristics of the buck-boost inverter, which is both an extension and a modification of conventional averaged model. Based on the unified mode, fast-scale bifurcation is identified, and the corresponding bifurcation point is predicted with the help of the locus movement of all the poles, and their underlying mechanisms are revealed. Detailed analysis shows that the occurrence of high-frequency oscillation means fast-scale bifurcation, while the occurrence of low-frequency oscillation leads to slow-scale bifurcation. Finally, it is demonstrated that the unified averaged model can provide not only a general method to investigate both the slow- and fast-scale bifurcations in a unified framework but also a quite straightforward design-oriented method which can be directly applicable.

scholarly journals Spatial variation in high-frequency oscillation rates and amplitudes in intracranial EEG

Neurology ◽  
2018 ◽  
Vol 90 (8) ◽  
pp. e639-e646 ◽  
Author(s):  
Hari Guragain ◽  
Jan Cimbalnik ◽  
Matt Stead ◽  
David M. Groppe ◽  
Brent M. Berry ◽  
...  
Keyword(s):  
High Frequency ◽  
Anatomic Variation ◽  
Brain Regions ◽  
Brain Atlas ◽  
Reproducible Research ◽  
High Frequency Oscillation ◽  
Seizure Onset ◽  
Frequency Oscillation ◽  
Intracranial Eeg ◽  
Seizure Onset Zone

ObjectiveTo assess the variation in baseline and seizure onset zone interictal high-frequency oscillation (HFO) rates and amplitudes across different anatomic brain regions in a large cohort of patients.MethodsSeventy patients who had wide-bandwidth (5 kHz) intracranial EEG (iEEG) recordings during surgical evaluation for drug-resistant epilepsy between 2005 and 2014 who had high-resolution MRI and CT imaging were identified. Discrete HFOs were identified in 2-hour segments of high-quality interictal iEEG data with an automated detector. Electrode locations were determined by coregistering the patient's preoperative MRI with an X-ray CT scan acquired immediately after electrode implantation and correcting electrode locations for postimplant brain shift. The anatomic locations of electrodes were determined using the Desikan-Killiany brain atlas via FreeSurfer. HFO rates and mean amplitudes were measured in seizure onset zone (SOZ) and non-SOZ electrodes, as determined by the clinical iEEG seizure recordings. To promote reproducible research, imaging and iEEG data are made freely available (msel.mayo.edu).ResultsBaseline (non-SOZ) HFO rates and amplitudes vary significantly in different brain structures, and between homologous structures in left and right hemispheres. While HFO rates and amplitudes were significantly higher in SOZ than non-SOZ electrodes when analyzed regardless of contact location, SOZ and non-SOZ HFO rates and amplitudes were not separable in some lobes and structures (e.g., frontal and temporal neocortex).ConclusionsThe anatomic variation in SOZ and non-SOZ HFO rates and amplitudes suggests the need to assess interictal HFO activity relative to anatomically accurate normative standards when using HFOs for presurgical planning.

Application of instantaneous-frequency attribute and gamma-ray wireline logs in the delineation of lithology in Serbin field, Southeast Texas: A case study

2018 ◽  
Vol 6 (4) ◽  
pp. T1023-T1043 ◽  
Author(s):  
Osareni C. Ogiesoba ◽  
William A. Ambrose ◽  
Robert G. Loucks
Keyword(s):  
Instantaneous Frequency ◽  
Acoustic Impedance ◽  
High Frequency ◽  
Gamma Ray ◽  
Low Frequency ◽  
High Porosity ◽  
Southeastern Part ◽  
High Gamma ◽  
Southeast Texas ◽  
Frequency Map

Although Serbin field in Southeast Texas was discovered in 1987, lithologic and petrophysical properties in the southeastern part of the field have not been fully evaluated. We have generated instantaneous frequency from 3D seismic data and predicted gamma-ray response volume from seismic attributes. By extracting maps of the instantaneous frequency and gamma-ray response along interpreted horizons, and crossplotting the instantaneous frequency against gamma-ray logs and integrating core data, we generated lithology maps to identify shale-prone zones that stratigraphically trapped hydrocarbons in the southeastern part of the field. We determine that Serbin field is separated into two areas: (1) a high-frequency, high-gamma-ray, and high-acoustic-impedance area in the northwest and (2) a low-frequency, low-gamma-ray, and low-acoustic-impedance area located in the southeast. By developing a lithologic map and relating it to the corresponding instantaneous-frequency map and log data, we also find that the southeastern part of the field can be divided into three zones: (1) zone 1, composed of approximately 0.7–2.7 m (approximately 2–8 ft) thick sandstone-rich beds of moderate frequency (25–30 Hz); (2) zone 2, composed of high-frequency (33–60 Hz) shale-rich zones that serve as stratigraphic-trapping-mechanisms; and (3) zone 3, composed of approximately 1.7–4 m (approximately 5–13 ft) thick sandstone-rich beds of low frequency (0–18 Hz) and relatively high porosity. These methods can be applied in other areas of the field with limited well control.

210. Spatiotemporal patterns of high frequency oscillation from intracranial EEG before and during seizure

2009 ◽  
Vol 16 (3) ◽  
pp. 472-473
Author(s):  
Karen Fuller ◽  
Dean Freestone ◽  
Simon Vogrin ◽  
Alan Lai ◽  
Levin Kuhlmann ◽  
...  
Keyword(s):  
High Frequency ◽  
Spatiotemporal Patterns ◽  
High Frequency Oscillation ◽  
Frequency Oscillation ◽  
Intracranial Eeg

scholarly journals Intracranial EEG in the 21st Century

2020 ◽  
Vol 20 (4) ◽  
pp. 180-188 ◽  
Author(s):  
Barbara C. Jobst ◽  
Fabrice Bartolomei ◽  
Beate Diehl ◽  
Birgit Frauscher ◽  
Philippe Kahane ◽  
...  
Keyword(s):  
Epilepsy Surgery ◽  
21St Century ◽  
High Frequency ◽  
Low Frequency ◽  
Epileptogenic Zone ◽  
Noninvasive Methods ◽  
Intracranial Eeg ◽  
Advantages And Disadvantages ◽  
Gamma Range ◽  
The Future

Intracranial electroencephalography (iEEG) has been the mainstay of identifying the seizure onset zone (SOZ), a key diagnostic procedure in addition to neuroimaging when considering epilepsy surgery. In many patients, iEEG has been the basis for resective epilepsy surgery, to date still the most successful treatment for drug-resistant epilepsy. Intracranial EEG determines the location and resectability of the SOZ. Advances in recording and implantation of iEEG provide multiple options in the 21st century. This not only includes the choice between subdural electrodes (SDE) and stereoelectroencephalography (SEEG) but also includes the implantation and recordings from microelectrodes. Before iEEG implantation, especially in magnetic resonance imaging -negative epilepsy, a clear hypothesis for seizure generation and propagation should be based on noninvasive methods. Intracranial EEG implantation should be planned by a multidisciplinary team considering epileptic networks. Recordings from SDE and SEEG have both their advantages and disadvantages. Stereo-EEG seems to have a lower rate of complications that are clinically significant, but has limitations in spatial sampling of the cortical surface. Stereo-EEG can sample deeper areas of the brain including deep sulci and hard to reach areas such as the insula.  To determine the epileptogenic zone, interictal and ictal information should be taken into consideration. Interictal spiking, low frequency slowing, as well as high frequency oscillations may inform about the epileptogenic zone. Ictally, high frequency onsets in the beta/gamma range are usually associated with the SOZ, but specialized recordings with combined macro and microelectrodes may in the future educate us about onset in higher frequency bands. Stimulation of intracranial electrodes triggering habitual seizures can assist in identifying the SOZ. Advanced computational methods such as determining the epileptogenicity index and similar measures may enhance standard clinical interpretation. Improved techniques to record and interpret iEEG may in the future lead to a greater proportion of patients being seizure free after epilepsy surgery.

Dynamic Spectral Imaging: Online and Offline Functional Brain Mapping Using High-Frequency Activity [50–150 Hz] in SEEG

2018 ◽  
pp. 453-464
Author(s):  
Jean-Philippe Lachaux
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
Human Cognition ◽  
Gamma Activity ◽  
Intracranial Eeg ◽  
Cortical Dynamics ◽  
Functional Brain Mapping ◽  
High Gamma ◽  
High Frequency Activity ◽  
Eeg Recordings

At the end of the twentieth century, a handful of research groups discovered that neural processing leaves a characteristic signature in intracranial EEG recordings: an increase of power in a broad frequency range above 50 Hz, dubbed ‘high-gamma’ of high-frequency activity ([50–150 Hz]). Since then, intracranial EEG research on human cognition has focused primarily on high-gamma activity to reveal the large-scale cortical dynamics of most major cognitive functions, not only offline in well-controlled paradigms, but also online, while patients freely interact with their environment. This chapter introduces that approach, including its recent extension to task-induced neural activity suppressions and functional connectivity mapping, and its clinical application to minimize cognitive deficits induced by epilepsy surgery.

scholarly journals Objective interictal electrophysiology biomarkers optimize prediction of epilepsy surgery outcome

2021 ◽  
Author(s):  
Naoto Kuroda ◽  
Masaki Sonoda ◽  
Makoto Miyakoshi ◽  
Hiroki Nariai ◽  
Jeong-Won Jeong ◽  
...  
Keyword(s):  
Standard Model ◽  
High Frequency ◽  
Classification Accuracy ◽  
Modulation Index ◽  
High Frequency Oscillation ◽  
Frequency Oscillation ◽  
Model Accuracy ◽  
Intracranial Eeg ◽  
Postoperative Seizure ◽  
Phase Amplitude

Abstract Researchers have looked for rapidly- and objectively-measurable electrophysiology biomarkers that accurately localize the epileptogenic zone. Promising candidates include interictal high-frequency oscillation and phase-amplitude coupling. Investigators have independently created the toolboxes that compute the high-frequency oscillation rate and the severity of phase-amplitude coupling. This study of 135 patients determined what toolboxes and analytic approaches would optimally classify patients achieving postoperative seizure control. Four different detector toolboxes computed the rate of high-frequency oscillation at ≥ 80 Hz at intracranial EEG channels. Another toolbox calculated the modulation index reflecting the strength of phase-amplitude coupling between high-frequency oscillation and slow-wave at 3-4 Hz. We defined the completeness of resection of interictally-abnormal regions as the subtraction of high-frequency oscillation rate (or modulation index) averaged across all preserved sites from that averaged across all resected sites. We computed the outcome classification accuracy of the logistic regression-based standard model considering clinical, ictal intracranial EEG, and neuroimaging variables alone. We then determined how well the incorporation of high-frequency oscillation/modulation index would improve the standard model mentioned above. To assess the anatomical variability across nonepileptic sites, we generated the normative atlas of detector-specific high-frequency oscillation and modulation index. Each atlas allowed us to compute the statistical deviation of high-frequency oscillation/modulation index from the nonepileptic mean. We determined whether the model accuracy would be improved by incorporating absolute or normalized high-frequency oscillation/modulation index as a biomarker assessing interictally-abnormal regions. We finally determined whether the model accuracy would be improved by selectively incorporating high-frequency oscillation verified to have high-frequency oscillatory components unattributable to a high-pass filtering effect. Ninety-five patients achieved successful seizure control, defined as International League Against Epilepsy class 1 outcome. Multivariate logistic regression analysis demonstrated that complete resection of interictally-abnormal regions additively increased the chance of success. The model accuracy was further improved by incorporating z-score normalized high-frequency oscillation/modulation index or selective incorporation of verified high-frequency oscillation. The standard model had a classification accuracy of 0.75. Incorporation of normalized high-frequency oscillation/modulation index or verified high-frequency oscillation improved the classification accuracy up to 0.82. These outcome prediction models survived the cross-validation process and demonstrated an agreement between the model-based likelihood of success and the observed success on an individual basis. Interictal high-frequency oscillation and modulation index had a comparably additive utility in epilepsy presurgical evaluation. Our empirical data support the theoretical notion that the prediction of postoperative seizure outcomes can be optimized with the consideration of both interictal and ictal abnormalities.

scholarly journals Intracranial-EEG evidence for medial temporal pole driving amygdala activity induced by multi-modal emotional stimuli

2020 ◽  
Author(s):  
Saurabh Sonkusare ◽  
Vinh Thai Nguyen ◽  
Rosalyn Moran ◽  
Johan van der Meer ◽  
Yudan Ren ◽  
...  
Keyword(s):  
Low Frequency ◽  
Gamma Activity ◽  
Cortical Region ◽  
Frequency Range ◽  
Intracranial Eeg ◽  
Social And Emotional ◽  
Temporal Pole ◽  
High Gamma ◽  
Amygdala Activity ◽  
Computational Analyses

AbstractThe temporal pole (TP) is an associative cortical region required for complex cognitive functions such as social and emotional cognition. However, functional mapping of the TP with functional magnetic resonance imaging is technically challenging and thus understanding of its interaction with other key emotional circuitry, such as the amygdala, remain elusive. We exploited the unique advantages of stereo-electroencephalography (SEEG) to assess the responses of the TP and the amygdala during the perception of emotionally salient stimuli of pictures, music and movies. These stimuli consistently elicited high gamma responses (70-140 Hz) in both the TP and the amygdala, accompanied by functional connectivity in the low frequency range (2-12 Hz). Computational analyses suggested the TP driving this effect in the theta-alpha frequency range and which was modulated by the emotional salience of the stimuli. Of note, cross-frequency analysis indicated the phase of theta-alpha oscillations in the TP modulated the amplitude of high gamma activity in the amygdala. These results were reproducible with three types of stimuli including naturalistic stimuli suggesting a hierarchical influence of the TP over the amygdala in non-threatening stimuli.

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