Pitfalls of high-pass filtering for detecting epileptic oscillations: A technical note on “false” ripples

Bénar, Christian; Chauvière, Laeticia; Bartolomei, Fabricē; Wendling, Fabrice

doi:10.1016/j.clinph.2009.10.019

Cited by 280 publications

(294 citation statements)

References 32 publications

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“…The time lag between two consecutive cycles had to be between 5 and 12.5 ms for ripples and between 2 and 4 ms for fast ripples (250-500 Hz). Oscillatory events containing overlapping ripples and fast ripples were excluded from the analysis (Bénar et al, 2010).…”

Section: Methodsmentioning

confidence: 99%

KCC2 function modulates in vitro ictogenesis

Hamidi

Avoli

2015

Neurobiology of Disease

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GABA A receptor-mediated inhibition is active and may contribute to epileptiform synchronization. The efficacy of inhibition relies on low levels of intracellular Cl − , which are controlled by KCC2 activity. This evidence has led us to analyze with field potential recordings the effects induced by the KCC2 blockers VU0240551 (10 μM) or bumetanide (50 μM) and by the KCC2 enhancer CLP257 (100 μM) on the epileptiform discharges generated by piriform and entorhinal cortices (PC and EC, respectively) in an in vitro brain slice preparation. Ictal-and interictal-like discharges along with high-frequency oscillations (HFOs, ripples: 80-200 Hz, fast ripples: 250-500 Hz) were recorded from these two regions during application of 4-aminopyridine (4AP, 50 μM). Blocking KCC2 activity with either VU024055 or high doses of bumetanide abolished ictal discharge in both PC and EC; in addition, these experimental procedures decreased the interval of occurrence and duration of interictal discharges. In contrast, enhancing KCC2 activity with CLP257 increased ictal discharge duration in both regions. Finally, blocking KCC2 activity decreased the duration and amplitude of pharmacologically isolated synchronous GABAergic events whereas enhancing KCC2 activity led to an increase in their duration. Our data demonstrate that in vitro ictogenesis is abolished or facilitated by inhibiting or enhancing KCC2 activity, respectively. We propose that these effects may result from the reduction of GABA A receptor-dependent increases in extracellular K + that are known to rest on KCC2 function.

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Section: Methodsmentioning

confidence: 99%

KCC2 function modulates in vitro ictogenesis

Hamidi

Avoli

2015

Neurobiology of Disease

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“…HFOs were kept for analysis only if the oscillatory event was visible in either the 80-200 or 250-500 Hz range. Overlapping events, which may be caused by the filtering of sharp spikes (Bénar et al, 2010), were excluded from the analysis. HFO rates were obtained for each ictal discharge and interictal discharge in the anterior and posterior subregions of the piriform cortex.…”

Section: Detection and Analysis Of High-frequency Oscillatory Eventsmentioning

confidence: 99%

Neurosteroids modulate epileptiform activity and associated high-frequency oscillations in the piriform cortex

Herrington

Lévesque

2014

Neuroscience

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Allotetrahydrodeoxycorticosterone (THDOC) belongs to a class of pregnane neurosteroidal compounds that enhance brain inhibition by interacting directly with GABA A signaling, mainly through an increase in tonic inhibitory current. Here, we addressed the role of THDOC in the modulation of interictal-and ictal-like activity and associated high-frequency oscillations (HFOs, 80-500 Hz; ripples: 80-200 Hz, fast ripples: 250-500 Hz) recorded in vitro in the rat piriform cortex, a highly excitable brain structure that is implicated in seizure generation and maintenance. We found that THDOC: (i) increased the duration of interictal discharges in the anterior piriform cortex while decreasing ictal discharge duration in both anterior and posterior piriform cortices; (ii) reduced the occurrence of HFOs associated to both interictal and ictal discharges; and (iii) prolonged the duration of 4-aminopyridine-induced, glutamatergic independent synchronous field potentials that are known to mainly result from the activation of GABA A receptors. Our results indicate that THDOC can modulate epileptiform synchronization in the piriform cortex presumably by potentiating GABA A receptor-mediated signaling. This evidence supports the view that neurosteroids regulate neuronal excitability and thus control the occurrence of seizures.

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“…Furthermore, special care was taken to avoid the detection of false HFOs, since ripples were kept for analysis only if they were visible in the 80 -200 Hz range, whereas fast ripples were kept only if they were visible in the 250 -500 Hz range. Overlapping events, which may be caused by the filtering of sharp spikes (Bénar et al, 2010), were thus excluded from the analysis. Visual validation was also performed to eliminate the false positive created by movement artifacts.…”

Section: Introductionmentioning

confidence: 99%

Two Seizure-Onset Types Reveal Specific Patterns of High-Frequency Oscillations in a Model of Temporal Lobe Epilepsy

2012

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High-frequencyoscillations(HFOs;80 -500Hz)arethoughttomirrorthepathophysiologicalchangesoccurringinepilepticbrains.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. We discovered in LVF seizures that (1) progressionfrompreictaltoictalactivitywascharacterizedinseizure-onsetzonesbyanincreaseofrippleratesthatwerehigherwhencomparedwithfast ripple rates and (2) ripple rates during the ictal period were higher compared with fast ripple rates in seizure-onset zones and later in regions of secondary spread. In contrast, we found in HYP seizures that (1) fast ripple rates increased during the preictal period and were higher compared with ripple rates in both seizure-onset zones and in regions of secondary spread and (2) they were still higher compared with ripple rates in both seizure-onset zones and regions of secondary spread during the ictal period. Our findings demonstrate that ripples and fast ripples show distinct time-and region-specific patterns during LVF and HYP seizures, thus suggesting that they play specific roles in ictogenesis.

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Pitfalls of high-pass filtering for detecting epileptic oscillations: A technical note on “false” ripples

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Cited by 280 publications

References 32 publications

KCC2 function modulates in vitro ictogenesis

KCC2 function modulates in vitro ictogenesis

Neurosteroids modulate epileptiform activity and associated high-frequency oscillations in the piriform cortex

Two Seizure-Onset Types Reveal Specific Patterns of High-Frequency Oscillations in a Model of Temporal Lobe Epilepsy

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