P339 Long-term electrocorticographic monitoring and pathological high-frequency oscillations in tumor-related epilepsy

2017 ◽  
Vol 128 (9) ◽  
pp. e288
Author(s):  
Nastasia Arkhipova ◽  
Mikhail Alexandrov ◽  
Alexander Chukhlovin ◽  
Marina Pavlovskaya ◽  
Irina Kostenko
Keyword(s):  
High Frequency ◽  
High Frequency Oscillations

scholarly journals Fast and slow cortical high frequency oscillations for cortico-cortical and cortico-hippocampal network consolidation during NonREM sleep

2019 ◽  
Author(s):  
Adrian Aleman-Zapata ◽  
Richard GM Morris ◽  
Lisa Genzel
Keyword(s):  
Memory Consolidation ◽  
High Frequency ◽  
Long Term Memory ◽  
Causality Analysis ◽  
Granger Causality Analysis ◽  
High Frequency Oscillations ◽  
New Information ◽  
Hippocampal Network ◽  
Nonrem Sleep

AbstractMemory reactivation during NonREM-ripples is thought to communicate new information to a systems-wide network. Cortical high frequency events have also been described that co-occur with ripples. Focusing on NonREM sleep after different behaviors, both hippocampal ripples and parietal high frequency oscillations were detected. A bimodal frequency distribution was observed in the parietal high frequency events, faster and slower, with increases in prefrontal directionality measured by Granger causality analysis specifically seen during the fast parietal oscillations. Furthermore, fast events activated prefrontal-parietal cortex whereas slow events activated hippocampal-parietal areas. Finally, there was a learning-induced increase in both number and size of fast high frequency events. These patterns were not seen after novelty exposure or foraging, but occurred after the learning of a new goal location in a maze. Disruption of either sleep or hippocampal ripples impaired long-term memory consistent with these having a role in memory consolidation.

scholarly journals Spatiotemporal patterns of high-frequency activity (80-170 Hz) in long-term intracranial EEG

2020 ◽  
Author(s):  
Zhuying Chen ◽  
David B. Grayden ◽  
Anthony N. Burkitt ◽  
Udaya Seneviratne ◽  
Wendyl J. D’Souza ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
High Frequency ◽  
Focal Epilepsy ◽  
Patient Specific ◽  
Intracranial Eeg ◽  
Electrode Implantation ◽  
High Frequency Oscillations ◽  
Total Data ◽  
High Frequency Activity

AbstractObjectiveTo assess the variability in the rates and locations of high-frequency activity (HFA) and epileptiform spikes after electrode implantation, and to examine the long-term patterns of HFA using ambulatory intracranial EEG (iEEG) recordings.MethodsContinuous iEEG recordings obtained over an average of 1.4 years from 15 patients with drug-resistant focal epilepsy were used in this study. HFA was defined as high-frequency events with amplitudes clearly larger than the background, which was automatically detected using a custom algorithm. High-frequency oscillations (HFOs) were also visually annotated by three neurologists in randomly sampled segments of the total data. The automatically detected HFA was compared with the visually marked HFOs. The variations of HFA rates were compared with spikes and seizures on patient-specific and electrode-specific bases.ResultsHFA was a more general event that encompassed HFOs manually annotated by different reviewers. HFA and spike rates had high amounts of intra- and inter-patient variability. The rates and locations of HFA and spikes took up to weeks to stabilize after electrode implantation in some patients. Both HFA and spike rates showed strong circadian rhythms in all patients and some also showed multiday cycles. Furthermore, the circadian patterns of HFA and spike rates had patient-specific correlations with seizures, which tended to vary across electrodes.ConclusionsAnalysis of HFA and epileptiform spikes should account for post-implantation variability. Like seizures, HFA and epileptiform spikes show circadian rhythms. However, the circadian profiles can vary spatially within patients and their correlations to seizures are patient-specific.

scholarly journals High Frequency Oscillations in SS Cygni

1989 ◽  
Vol 114 ◽  
pp. 462-464
Author(s):  
M.J. Arévalo ◽  
J.E. Solheim ◽  
C. Lázaro
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Cataclysmic Variable ◽  
Dwarf Novae ◽  
High Frequency Oscillations ◽  
Relative Brightness ◽  
High Speed Photometry

Because of its relative brightness (mv about 11.8 in quiescence and mv about 8.6 in outburst), SS Cygni is the Dwarf Novae most extensively studied since 1896 (Mattei et al., 1985; Bath and van Paradijs, 1983).Concerning its long-term behaviour, SS Cygni has short, long and anomalous out-bursts. Correlations between outburst characteristics and periodicities have been studied by van Paradijs (1983), Campbell (1934), and Sterne and Campbell (1934).SS Cygni, as any cataclysmic variable, also presents rapid variations. Since the discovery of this variability (Warner and Robinson, 1972) many long runs of high-speed photometry have been performed for different Dwarf Novae, both during out-bursts and in quiescence stages. Regarding to SS Cygni we can summarize these variations as:

High-frequency Oscillations in Epilepsy: What Have We Learned and What Needs to be Addressed

Neurology ◽  
2021 ◽  
pp. 10.1212/WNL.0000000000011465 ◽  
Author(s):  
Zhuying Chen ◽  
Matias I. Maturana ◽  
Anthony N. Burkitt ◽  
Mark J. Cook ◽  
David B. Grayden
Keyword(s):  
High Frequency ◽  
Future Research ◽  
Great Promise ◽  
Clinical Biomarkers ◽  
High Frequency Oscillations ◽  
Visual Identification ◽  
Current State ◽  
Open Questions ◽  
Term Data

For the past two decades, high-frequency oscillations (HFOs) have been enthusiastically studied by the epilepsy community. Emerging evidence shows that HFOs harbour great promise to delineate epileptogenic brain areas and possibly predict the likelihood of seizures. Investigations into HFOs in clinical epilepsy have advanced from small retrospective studies relying on visual identification and correlation analysis to larger prospective assessments using automatic detection and prediction strategies. While most studies have yielded promising results, some have revealed significant obstacles to clinical application of HFOs, thus raising debate about the reliability and practicality of HFOs as clinical biomarkers. In this review, we give an overview of the current state of HFO research and pinpoint the conceptual and methodological issues that have hampered HFO translation. We highlight recent insights gained from long-term data, high-density recordings and multicentre collaborations, and discuss the open questions that need to be addressed in future research.

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