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https://www.readbyqxmd.com/read/28158285/asynchronous-ripple-oscillations-between-left-and-right-hippocampi-during-slow-wave-sleep
#1
Claudio Villalobos, Pedro E Maldonado, José L Valdés
Spatial memory, among many other brain processes, shows hemispheric lateralization. Most of the published evidence suggests that the right hippocampus plays a leading role in the manipulation of spatial information. Concurrently in the hippocampus, memory consolidation during sleep periods is one of the key steps in the formation of newly acquired spatial memory traces. One of the most characteristic oscillatory patterns in the hippocampus are sharp-wave ripple (SWR) complexes. Within this complex, fast-field oscillations or ripples have been demonstrated to be instrumental in the memory consolidation process...
2017: PloS One
https://www.readbyqxmd.com/read/28131532/high-frequency-spectral-changes-induced-by-single-pulse-electric-stimulation-comparison-between-physiologic-and-pathologic-networks
#2
Mihai Dragos Mălîia, Cristian Donos, Andrei Barborica, Ioana Mindruta, Irina Popa, Mirela Ene, Sándor Beniczky
OBJECTIVE: To investigate functional coupling between brain networks using spectral changes induced by single-pulse electric stimulation (SPES). METHOD: We analyzed 20 patients with focal epilepsy, implanted with depth electrodes. SPES was applied to each pair of adjacent contacts, and responses were recorded from all other contacts. The mean response amplitude value was quantified in three time-periods after stimulation (10-60, 60-255, 255-500ms) for three frequency-ranges (Gamma, Ripples, Fast-Ripples), and compared to baseline...
December 28, 2016: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28115239/high-frequency-oscillations-and-mesial-temporal-lobe-epilepsy
#3
REVIEW
Maxime Lévesque, Zahra Shiri, Li-Yuan Chen, Massimo Avoli
The interest of epileptologists has recently shifted from the macroscopic analysis of interictal spikes and seizures to the microscopic analysis of short events in the EEG that are not visible to the naked eye but are observed once the signal has been filtered in specific frequency bands. With the use of new technologies that allow multichannel recordings at high sampling rates and the development of computer algorithms that permit the automated analysis of extensive amounts of data, it is now possible to extract high-frequency oscillations (HFOs) between 80 and 500Hz from the EEG; HFOs have been further categorised as ripples (80-200Hz) and fast ripples (250-500Hz)...
January 20, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/28113293/automatic-detection-and-classification-of-high-frequency-oscillations-in-depth-eeg-signals
#4
Nisrine Jrad, Amar Kachenoura, Isabelle Merlet, Fabrice Bartolomei, Anca Nica, Arnaud Biraben, Fabrice Wendling
GOAL: Interictal High Frequency Oscillations (HFOs [30-600 Hz]) have proven to be relevant biomarkers in epilepsy. In this paper, four categories of HFOs are considered: Gamma ([30- 80 Hz]), High-Gamma ([80-120 Hz]), Ripples ([120-250 Hz]) and Fast-Ripples ([250-600 Hz]). A universal detector of the four types of HFOs is proposed. It has the advantages of i) classifying HFOs, and thus being robust to inter- and intra-subject variability; ii) rejecting artefacts, thus being specific. METHODS: Gabor atoms are tuned to cover the physiological bands...
November 29, 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28107659/high-frequency-oscillations-and-seizure-like-discharges-in-the-entorhinal-cortex-of-the-in-vitro-isolated-guinea-pig-brain
#5
Laura Uva, Davide Boido, Massimo Avoli, Marco de Curtis, Maxime Lévesque
We analyzed the patterns of seizure-like activity and associated high-frequency oscillations (HFOs) induced by the K(+) channel blocker 4-aminopyridine (4AP, 50μM) or the GABAA receptor antagonist bicuculline methiodide (BMI, 50μM) in the in vitro isolated guinea pig brain preparation. Extracellular field recordings were obtained from the medial entorhinal cortex (EC) using glass pipettes or silicon probes; 4AP or BMI were applied through the basilar artery. Ripples (80-200Hz) or fast ripples (250-500Hz) occurred at higher rates shortly before ictal events induced by 4AP or BMI, respectively...
January 6, 2017: Epilepsy Research
https://www.readbyqxmd.com/read/28050973/behavioral-state-classification-in-epileptic-brain-using-intracranial-electrophysiology
#6
Vaclav Kremen, Juliano J Duque, Benjamin H Brinkmann, Brent M Berry, Michal T Kucewicz, Fatemeh Khadjevand, Jamie Van Gompel, Matt Stead, Erik K St Louis, Gregory A Worrell
OBJECTIVE: Automated behavioral state classification can benefit next generation implantable epilepsy devices. In this study we explored the feasibility of automated awake (AW) and slow wave sleep (SWS) classification using wide bandwidth intracranial EEG (iEEG) in patients undergoing evaluation for epilepsy surgery. APPROACH: Data from seven patients (age [Formula: see text], 4 women) who underwent intracranial depth electrode implantation for iEEG monitoring were included...
January 4, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/27965619/dynamic-changes-in-spectral-and-spatial-signatures-of-high-frequency-oscillations-in-rat-hippocampi-during-epileptogenesis-in-acute-and-chronic-stages
#7
Pan-Pan Song, Jing Xiang, Li Jiang, Heng-Sheng Chen, Ben-Ke Liu, Yue Hu
OBJECTIVE: To analyze spectral and spatial signatures of high frequency oscillations (HFOs), which include ripples and fast ripples (FRs, >200 Hz) by quantitatively assessing average and peak spectral power in a rat model of different stages of epileptogenesis. METHODS: The lithium-pilocarpine model of temporal lobe epilepsy was used. The acute phase of epilepsy was assessed by recording intracranial electroencephalography (EEG) activity for 1 day after status epilepticus (SE)...
2016: Frontiers in Neurology
https://www.readbyqxmd.com/read/27913322/automatic-detection-and-classification-of-high-frequency-oscillations-in-depth-eeg-signals
#8
Nisrine Jrad, Amar Kachenoura, Isabelle Merlet, Fabrice Bartolomei, Anca Nica, Arnaud Biraben, Fabrice Wendling
GOAL: Interictal High Frequency Oscillations (HFOs [30-600 Hz]) have proven to be relevant biomarkers in epilepsy. In this paper, four categories of HFOs are considered: Gamma ([30- 80 Hz]), High-Gamma ([80-120 Hz]), Ripples ([120-250 Hz]) and Fast-Ripples ([250-600 Hz]). A universal detector of the four types of HFOs is proposed. It has the advantages of i) classifying HFOs, and thus being robust to inter- and intra-subject variability; ii) rejecting artefacts, thus being specific. METHODS: Gabor atoms are tuned to cover the physiological bands...
November 29, 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/27912169/non-harmonicity-in-high-frequency-components-of-the-intra-operative-corticogram-to-delineate-epileptogenic-tissue-during-surgery
#9
Evelien E Geertsema, Maryse A van 't Klooster, Nicole E C van Klink, Frans S S Leijten, Peter C van Rijen, Gerhard H Visser, Stiliyan N Kalitzin, Maeike Zijlmans
OBJECTIVE: We aimed to test the potential of auto-regressive model residual modulation (ARRm), an artefact-insensitive method based on non-harmonicity of the high-frequency signal, to identify epileptogenic tissue during surgery. METHODS: Intra-operative electrocorticography (ECoG) of 54 patients with refractory focal epilepsy were recorded pre- and post-resection at 2048Hz. The ARRm was calculated in one-minute epochs in which high-frequency oscillations (HFOs; fast ripples, 250-500Hz; ripples, 80-250Hz) and spikes were marked...
January 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/27900948/prediction-of-antiepileptic-drug-treatment-outcomes-using-machine-learning
#10
Sinisa Colic, Robert G Wither, Min Lang, Liang Zhang, James H Eubanks, Berj L Bardakjian
OBJECTIVE: Antiepileptic drug (AED) treatments produce inconsistent outcomes, often necessitating patients to go through several drug trials until a successful treatment can be found. This study proposes the use of machine learning techniques to predict epilepsy treatment outcomes of commonly used AEDs. APPROACH: Machine learning algorithms were trained and evaluated using features obtained from intracranial electroencephalogram (iEEG) recordings of the epileptiform discharges observed in Mecp2-deficient mouse model of the Rett Syndrome...
November 30, 2016: Journal of Neural Engineering
https://www.readbyqxmd.com/read/27896067/relationship-between-high-frequency-oscillations-and-spikes-in-a-case-of-temporal-lobe-epilepsy
#11
Vishwanath Sagi, M Steven Evans
OBJECTIVE: The aim of this case report was to study the relationship between high-frequency oscillations (HFOs), spikes, and seizures in a patient with temporal lobe epilepsy. INTRODUCTION: During intracranial electroencephalography (EEG), HFOs are thought to be a marker for the seizure onset zone (SOZ). High-frequency oscillations are classified into ripples with frequencies of 70-200 Hz and fast ripples with frequencies of 200-500 Hz. Although HFOs are thought to be a marker for the SOZ, their relationship to spikes has not been studied in detail, especially within the SOZ...
2016: Epilepsy & Behavior Case Reports
https://www.readbyqxmd.com/read/27883965/frequency-independent-characteristics-of-high-frequency-oscillations-in-epileptic-and-non-epileptic-regions
#12
Martin Pail, Pavel Řehulka, Jan Cimbálník, Irena Doležalová, Jan Chrastina, Milan Brázdil
OBJECTIVE: The purpose of the presented study is to determine whether there are frequency-independent high-frequency oscillation (HFO) parameters which may differ in epileptic and non-epileptic regions. METHODS: We studied 31 consecutive patients with medically intractable focal (temporal and extratemporal) epilepsies who were examined by either intracerebral or subdural electrodes. Automated detection was used to detect HFO. The characteristics (rate, amplitude, and duration) of HFO were statistically compared within three groups: the seizure onset zone (SOZ), the irritative zone (IZ), and areas outside the IZ and SOZ (nonSOZ/nonIZ)...
January 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/27882298/high-frequency-oscillations-and-high-frequency-functional-network-characteristics-in-the-intraoperative-electrocorticogram-in-epilepsy
#13
W J E M Zweiphenning, M A van 't Klooster, E van Diessen, N E C van Klink, G J M Huiskamp, T A Gebbink, F S S Leijten, P H Gosselaar, W M Otte, C J Stam, K P J Braun, G J M Zijlmans
OBJECTIVE: High frequency oscillations (HFOs; > 80 Hz), especially fast ripples (FRs, 250-500 Hz), are novel biomarkers for epileptogenic tissue. The pathophysiology suggests enhanced functional connectivity within FR generating tissue. Our aim was to determine the relation between brain areas showing FRs and 'baseline' functional connectivity within EEG networks, especially in the high frequency bands. METHODS: We marked FRs, ripples (80-250 Hz) and spikes in the electrocorticogram of 14 patients with refractory temporal lobe epilepsy...
2016: NeuroImage: Clinical
https://www.readbyqxmd.com/read/27881950/a-new-approach-of-modified-submerged-patch-clamp-recording-reveals-interneuronal-dynamics-during-epileptiform-oscillations
#14
Gareth Morris, Premysl Jiruska, John G R Jefferys, Andrew D Powell
Highlights Simultaneous epileptiform LFPs and single-cell activity can be recorded in the membrane chamber.Interneuron firing can be linked to epileptiform high frequency activity.Fast ripples, unique to chronic epilepsy, can be modeled in ex vivo tissue from TeNT-treated rats. Traditionally, visually-guided patch clamp in brain slices using submerged recording conditions has been required to characterize the activity of individual neurons. However, due to limited oxygen availability, submerged conditions truncate fast network oscillations including epileptiform activity...
2016: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/27746131/identified-cellular-correlates-of-neocortical-ripple-and-high-gamma-oscillations-during-spindles-of-natural-sleep
#15
Robert G Averkin, Viktor Szemenyei, Sándor Bordé, Gábor Tamás
Ultra-high-frequency network events in the hippocampus are instrumental in a dialogue with the neocortex during memory formation, but the existence of transient ∼200 Hz network events in the neocortex is not clear. Our recordings from neocortical layer II/III of freely behaving rats revealed field potential events at ripple and high-gamma frequencies repeatedly occurring at troughs of spindle oscillations during sleep. Juxtacellular recordings identified subpopulations of fast-spiking, parvalbumin-containing basket cells with epochs of firing at ripple (∼200 Hz) and high-gamma (∼120 Hz) frequencies detected during spindles and centered with millisecond precision at the trough of spindle waves in phase with field potential events but phase shifted relative to pyramidal cell firing...
November 23, 2016: Neuron
https://www.readbyqxmd.com/read/27721161/prospective-and-live-fast-ripple-detection-and-localization-in-the-operating-room-impact-on-epilepsy-surgery-outcomes-in-children
#16
Shaun A Hussain, Gary W Mathern, Raman Sankar, Joyce Y Wu
OBJECTIVE: Fast ripples (FR, 250-500Hz) are proposed biomarkers of the epileptogenic zone on the basis of several retrospective reports linking postoperative seizure freedom to their complete resection. There are no clinical trials or prospective reports validating the use of FR as characterized by electrocorticography (ECoG), to guide the scope of epilepsy surgery, and to inform prognosis thereafter. We set out to prospectively evaluate the utility of FR resection to predict postoperative epilepsy outcomes, and examine the feasibility of "live" intraoperative FR ascertainment...
September 23, 2016: Epilepsy Research
https://www.readbyqxmd.com/read/27647753/temperature-controlled-high-speed-afm-real-time-observation-of-ripple-phase-transitions
#17
Hirohide Takahashi, Atsushi Miyagi, Lorena Redondo-Morata, Simon Scheuring
With nanometer lateral and Angstrom vertical resolution, atomic force microscopy (AFM) has contributed unique data improving the understanding of lipid bilayers. Lipid bilayers are found in several different temperature-dependent states, termed phases; the main phases are solid and fluid phases. The transition temperature between solid and fluid phases is lipid composition specific. Under certain conditions some lipid bilayers adopt a so-called ripple phase, a structure where solid and fluid phase domains alternate with constant periodicity...
September 20, 2016: Small
https://www.readbyqxmd.com/read/27645468/load-estimator-based-hybrid-controller-design-for-two-interleaved-boost-converter-dedicated-to-renewable-energy-and-automotive-applications
#18
Mohamed Bougrine, Mohammed Benmiloud, Atallah Benalia, Emmanuel Delaleau, Mohamed Benbouzid
This paper is devoted to the development of a hybrid controller for a two-interleaved boost converter dedicated to renewable energy and automotive applications. The control requirements, resumed in fast transient and low input current ripple, are formulated as a problem of fast stabilization of a predefined optimal limit cycle, and solved using hybrid automaton formalism. In addition, a real time estimation of the load is developed using an algebraic approach for online adjustment of the hybrid controller. Mathematical proofs are provided with simulations to illustrate the effectiveness and the robustness of the proposed controller despite different disturbances...
September 16, 2016: ISA Transactions
https://www.readbyqxmd.com/read/27635628/intracranial-eeg-seizure-onset-patterns-correlate-with-high-frequency-oscillations-in-patients-with-drug-resistant-epilepsy
#19
Taissa Ferrari-Marinho, Piero Perucca, Francois Dubeau, Jean Gotman
OBJECTIVE: High-frequency oscillations (80-500Hz; HFOs) have been shown to be a specific biomarker of the seizure-onset zone. The relationship of HFOs with seizures having different intracranial electroencephalography (iEEG) morphological onsets, however, has shown significant relationships in experimental animals but has not been studied in humans. We investigated how interictal and ictal HFOs relate to different seizure-onset morphological patterns. METHODS: We analyzed the most representative seizure type of 37 patients with drug-resistant focal epilepsy who underwent iEEG for diagnostic evaluation...
September 6, 2016: Epilepsy Research
https://www.readbyqxmd.com/read/27479916/downstream-effects-of-hippocampal-sharp-wave-ripple-oscillations-on-medial-entorhinal-cortex-layer-v-neurons-in-vitro
#20
Fabian C Roth, Katinka M Beyer, Martin Both, Andreas Draguhn, Alexei V Egorov
The entorhinal cortex (EC) is a critical component of the medial temporal lobe (MTL) memory system. Local networks within the MTL express a variety of state-dependent network oscillations that are believed to organize neuronal activity during memory formation. The peculiar pattern of sharp wave-ripple complexes (SPW-R) entrains neurons by a very fast oscillation at ∼200 Hz in the hippocampal areas CA3 and CA1 and then propagates through the "output loop" into the EC. The precise mechanisms of SPW-R propagation and the resulting cellular input patterns in the mEC are, however, largely unknown...
December 2016: Hippocampus
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