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fast ripple

Hui Zhang, Juergen Fell, Nikolai Axmacher
Consolidation stabilizes memory traces after initial encoding. Rodent studies suggest that memory consolidation depends on replay of stimulus-specific activity patterns during fast hippocampal "ripple" oscillations. Here, we measured replay in intracranial electroencephalography recordings in human epilepsy patients, and related replay to ripples. Stimulus-specific activity was identified using representational similarity analysis and then tracked during waking rest and sleep after encoding. Stimulus-specific gamma (30-90 Hz) activity during early (100-500 ms) and late (500-1200 ms) encoding is spontaneously reactivated during waking state and sleep, independent of later memory...
October 5, 2018: Nature Communications
S Phelan, T A Hagobian, A Ventura, A Brannen, K Erickson-Hatley, A Schaffner, K Muñoz-Christian, A Mercado, D F Tate
BACKGROUND: Weight loss interventions can have positive 'ripple' effects on untreated partners in the home, but ripple effects on infants are unknown. OBJECTIVE: To examine whether a 12-month internet-based weight loss intervention for postpartum mothers had a positive ripple effect on participants' infants. METHODS: A 12-month cluster randomized, assessor-blind, clinical trial enrolling 371 postpartum women at 12 Women, Infants, Children clinics in CA...
September 17, 2018: Pediatric Obesity
Franco Ortiz, W P Karel Zapfe, Andreas Draguhn, Rafael Gutiérrez
Fast ripples (FRs; activity of >250 Hz) have been considered as a biomarker of epileptic activity in the hippocampus and entorhinal cortex; it is thought that they signal the focus of seizure generation. Similar high-frequency network activity has been produced in vitro by changing extracellular medium composition, by using pro-epileptic substances, or by electrical stimulation. Here we study the propagation of these events between different subregions of the male rat hippocampus in a recently introduced experimental model of FRs in entorhinal cortex-hippocampal slices in vitro By using a matrix of 4096 microelectrodes, the sites of initiation, propagation pathways, and spatiotemporal characteristics of activity patterns could be studied with unprecedented high resolution...
October 17, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Lei Wang, Qi-Dai Chen, Xiao-Wen Cao, Ričardas Buividas, Xuewen Wang, Saulius Juodkazis, Hong-Bo Sun
The lossy nature of plasmonic wave due to absorption is shown to become an advantage for scaling-up a large area surface nanotexturing of transparent dielectrics and semiconductors by a self-organized sub-wavelength energy deposition leading to an ablation pattern-ripples-using this plasmonic nano-printing. Irreversible nanoscale modifications are delivered by surface plasmon polariton (SPP) using: (i) fast scan and (ii) cylindrical focusing of femtosecond laser pulses for a high patterning throughput. The mechanism of ripple formation on ZnS dielectric is experimentally proven to occur via surface wave at the substrate-plasma interface...
December 2017: Light, Science & Applications
Takashi Shibata, Katsuhiro Kobayashi
Electroencephalography (EEG) examines the functional state of the brain. High-frequency oscillations (HFOs) in the ripple (80-200/250 Hz) and fast ripple (200/250-500/600 Hz) bands have recently been attracting attention, and their recording has been enabled by advancements in digital EEG techniques. The detection of HFOs was previously limited to intracranial EEG, but fast oscillations (FOs) in the gamma (40-80 Hz) and ripple bands can now be detected over the scalp. HFOs and FOs have been shown to be related to epileptogenicity in intracranial EEG and scalp EEG, respectively...
August 2018: Acta Medica Okayama
Julia Jacobs, Joyce Y Wu, Piero Perucca, Rina Zelmann, Malenka Mader, Francois Dubeau, Gary W Mathern, Andreas Schulze-Bonhage, Jean Gotman
OBJECTIVE: To evaluate the use of interictal high-frequency oscillations (HFOs) in epilepsy surgery for prediction of postsurgical seizure outcome in a prospective multicenter trial. METHODS: We hypothesized that a seizure-free outcome could be expected in patients in whom the surgical planning included the majority of HFO-generating brain tissue while a poor seizure outcome could be expected in patients in whom only a few such areas were planned to be resected...
September 11, 2018: Neurology
Saradha Ananthakrishnan, Ananthanarayan Krishnan
The perceived pitch of iterated rippled noise (IRN) with negative gain (IRNn) is an octave lower than that of IRN with positive gain (IRNp). IRNp and IRNn have identical waveform envelopes (ENV), but differing stimulus waveform fine structure (TFS), which likely accounts for this perceived pitch difference. Here, we examine whether differences in the temporal pattern of phase-locked activity reflected in the human brainstem Frequency Following Response (FFR) elicited by IRNp and IRNn can account for the differences in perceived pitch for the two stimuli...
September 2018: Hearing Research
Shennan Aibel Weiss, Brent Berry, Inna Chervoneva, Zachary Waldman, Jonathan Guba, Mark Bower, Michal Kucewicz, Benjamin Brinkmann, Vaclav Kremen, Fatemeh Khadjevand, Yogatheesan Varatharajah, Hari Guragain, Ashwini Sharan, Chengyuan Wu, Richard Staba, Jerome Engel, Michael Sperling, Gregory Worrell
OBJECTIVE: To test the utility of a novel semi-automated method for detecting, validating, and quantifying high-frequency oscillations (HFOs): ripples (80-200 Hz) and fast ripples (200-600 Hz) in intra-operative electrocorticography (ECoG) recordings. METHODS: Sixteen adult patients with temporal lobe epilepsy (TLE) had intra-operative ECoG recordings at the time of resection. The computer-annotated ECoG recordings were visually inspected and false positive detections were removed...
October 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Xiao Ran, Jing Xiang, Pan-Pan Song, Li Jiang, Ben-Ke Liu, Yue Hu
OBJECTIVE: To assess the dynamic changes in the average and peak spectral power of fast ripples (FRs) in the hippocampi after interventions with valproate sodium (VPA), carbenoxolone (CBX) and quinine (QUIN). METHOD: Adult rats were used to establish a lithium-pilocarpine (pilo) epileptic model, and were assigned to a lithium-pilocarpine (PILO), VPA + PILO, QUIN + PILO or CBX + PILO group. Intracranial electroencephalography was performed before and after status epilepticus (SE)...
October 2018: Epilepsy Research
Birgit Frauscher, Nicolás von Ellenrieder, Rina Zelmann, Christine Rogers, Dang Khoa Nguyen, Philippe Kahane, François Dubeau, Jean Gotman
OBJECTIVE: High-frequency oscillations (HFOs) are a promising biomarker for the epileptogenic zone. It has not been possible, however, to differentiate physiological from pathological HFOs, and baseline rates of HFO occurrence vary substantially across brain regions. This project establishes region-specific normative values for physiological HFOs and high-frequency activity (HFA). METHODS: Intracerebral stereo-encephalographic recordings with channels displaying normal physiological activity from nonlesional tissue were selected from 2 tertiary epilepsy centers...
July 26, 2018: Annals of Neurology
Liyuan Zhang, Denggui Fan, Qingyun Wang
Studies on the structural-functional connectomes of the human brain have demonstrated the existence of synchronous firings in a specific brain network motif. In particular, synchronization of high-frequency oscillations (HFOs) has been observed in the experimental data sets of temporal lobe epilepsy (TLE). In addition, both clinical and experimental evidences have accumulated to demonstrate the effect of electrical stimulation on TLE, which, however, remains largely unexplored. In this work, we first employ our previously proposed dentate gyrus (DG)-CA3 network model to investigate the influence of an external electrical stimulus on the HFO transitions...
June 2018: Chaos
Jean Gotman
No abstract text is available yet for this article.
July 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Oriol Gonzalez, Tesfalem G Welearegay, Xavier Vilanova, Eduard Llobet
Here we report on the use of pulsed UV light for activating the gas sensing response of metal oxides. Under pulsed UV light, the resistance of metal oxides presents a ripple due to light-induced transient adsorption and desorption phenomena. This methodology has been applied to tungsten oxide nanoneedle gas sensors operated either at room temperature or under mild heating (50 °C or 100 °C). It has been found that by analyzing the rate of resistance change caused by pulsed UV light, a fast determination of gas concentration is achieved (ten-fold improvement in response time)...
April 26, 2018: Sensors
Danilo Bernardo, Hiroki Nariai, Shaun A Hussain, Raman Sankar, Noriko Salamon, Darcy A Krueger, Mustafa Sahin, Hope Northrup, E Martina Bebin, Joyce Y Wu
OBJECTIVES: We aim to establish that interictal fast ripples (FR; 250-500 Hz) are detectable on scalp EEG, and to investigate their association to epilepsy. METHODS: Scalp EEG recordings of a subset of children with tuberous sclerosis complex (TSC)-associated epilepsy from two large multicenter observational TSC studies were analyzed and compared to control children without epilepsy or any other brain-based diagnoses. FR were identified both by human visual review and compared with semi-automated review utilizing a deep learning-based FR detector...
July 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Laurent Sheybani, Gwenaël Birot, Alessandro Contestabile, Margitta Seeck, Jozsef Zoltan Kiss, Karl Schaller, Christoph M Michel, Charles Quairiaux
Most research on focal epilepsy focuses on mechanisms of seizure generation in the primary epileptic focus (EF). However, neurological deficits that are not directly linked to seizure activity and that may persist after focus removal are frequent. The recruitment of remote brain regions of an epileptic network (EN) is recognized as a possible cause, but a profound lack of experimental evidence exists concerning their recruitment and the type of pathological activities they exhibit. We studied the development of epileptic activities at the large-scale in male mice of the kainate model of unilateral temporal lobe epilepsy using high-density surface EEG and multiple-site intracortical recordings...
April 11, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Fatemeh Khadjevand, Jan Cimbalnik, Gregory A Worrell
High-frequency oscillations (HFOs: 100 - 600 Hz) have been widely proposed as biomarkers of epileptic brain tissue. In addition, HFOs over a broader range of frequencies spanning 30 - 2000 Hz are potential biomarkers of both physiological and pathological brain processes. The majority of the results from humans with focal epilepsy have focused on HFOs recorded directly from the brain with intracranial EEG (iEEG) in the high gamma (65 - 100 Hz), ripple (100 - 250 Hz), and fast ripple (250 - 600 Hz) frequency ranges...
December 2017: Current Opinion in Biomedical Engineering
C Cuello-Oderiz, N von Ellenrieder, R Sankhe, A Olivier, J Hall, F Dubeau, J Gotman
OBJECTIVES: There are different neurophysiological markers of the Epileptogenic Zone (EZ), but their sensitivity and specificity for the EZ is not known in Focal Cortical Dysplasia (FCD) patients. METHODS: We studied patients with FCD who underwent stereoelectroencephalography (SEEG) and surgery. We marked in the SEEG: (a) typical and atypical interictal epileptiform patterns, (b) ictal onset patterns, and (c) rates of ripples (80-250 Hz) and fast ripples (FRs) (>250 Hz)...
June 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Lin Li, Mayur Patel, Joyel Almajano, Jerome Engel, Anatol Bragin
The current study aimed to investigate the spatial and temporal patterns of high-frequency oscillations (HFOs) in the intra-/extrahippocampal areas during epileptogenesis. Local field potentials were bilaterally recorded from hippocampus (CA1), thalamus, motor cortex, and prefrontal cortex in 13 rats before and after intrahippocampal kainic acid (KA) lesions. HFOs in the ripple (100-200 Hz) and fast ripple (250-500 Hz) ranges were detected and their rates were computed during different time periods (1-5 weeks) after KA-induced status epilepticus (SE)...
April 2018: Epilepsia
Mohamad Shamas, Pascal Benquet, Isabelle Merlet, Mohamad Khalil, Wassim El Falou, Anca Nica, Fabrice Wendling
OBJECTIVE: In this study we aim to identify the key (patho)physiological mechanisms and biophysical factors which impact the observability and spectral features of High Frequency Oscillations (HFOs). METHODS: In order to accurately replicate HFOs we developed virtual-brain/virtual-electrode simulation environment combining novel neurophysiological models of neuronal populations with biophysical models for the source/sensor relationship. Both (patho)physiological mechanisms (synaptic transmission, depolarizing GABAA effect, hyperexcitability) and physical factors (geometry of extended cortical sources, size and position of electrodes) were taken into account...
April 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Maxime Lévesque, Siyan Wang, Jean Gotman, Massimo Avoli
BACKGROUND: The detection of high-frequency oscillations (HFOs, ripples: 80-200 Hz, fast ripples: 250-500 Hz) is often based on considering ripples or fast ripples in isolation; overlapping ripples and fast ripples are excluded from further analysis. Here, we studied overlapping HFOs during spontaneous seizures in pilocarpine-treated animals. NEW METHOD: Spontaneous seizures (n = 6 animals) presented with either hypersynchronous- (HYP, n = 18) or low-voltage fast-onset (LVF, n = 21) pattern...
April 1, 2018: Journal of Neuroscience Methods
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