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https://www.readbyqxmd.com/read/28728081/brain-state-dependent-recruitment-of-high-frequency-oscillations-in-the-human-hippocampus
#1
Pablo Billeke, Tomas Ossandon, Marcelo Stockle, Marcela Perrone-Bertolotti, Philippe Kahane, Jean-Philippe Lachaux, Pablo Fuentealba
Ripples are high-frequency bouts of coordinated hippocampal activity believed to be crucial for information transfer and memory formation. We used intracortical macroelectrodes to record neural activity in the human hippocampus of awake subjects undergoing surgical treatment for refractory epilepsy and distinguished two populations of ripple episodes based on their frequency spectrum. The phase-coupling of one population, slow ripples (90-110 Hz), to cortical delta oscillations was differentially modulated by cognitive task; whereas the second population, fast ripples (130-170 Hz), was not seemingly correlated to local neural activity...
June 23, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/28709992/time-dependent-evolution-of-seizures-in-a-model-of-mesial-temporal-lobe-epilepsy
#2
Charles Behr, Maxime Lévesque, Thomas Stroh, Massimo Avoli
Low-voltage fast (LVF) and hypersynchronous (HYP) - onset seizures occur in the EEG obtained with depth electrodes from mesial temporal lobe epilepsy (MTLE) patients and animal models. In epileptic rats analyzed up to approximately two weeks after pilocarpine-induced status epilepticus (SE), these patterns are associated with specific high-frequency oscillation (HFO) content: ripples (80-200Hz) or fast-ripples (250-500Hz) predominate in LVF or HYP seizures, respectively. To establish whether these features change over the course of the disease, we recorded the EEG from the hippocampal CA3 subfield, subiculum, entorhinal cortex and dentate gyrus in two groups of pilocarpine-treated rats: the "early stage group" (n=8) was analyzed from day 3 to 20 post-SE while the "late stage group" (n=7) was studied from day 27 to 53 post-SE...
July 12, 2017: Neurobiology of Disease
https://www.readbyqxmd.com/read/28673833/the-glutamate-receptor-antagonists-cnqx-and-mpep-decrease-fast-ripple-events-in-rats-treated-with-kainic-acid
#3
Laura Medina-Ceja, Carla García-Barba
Fast ripples (FR) are high frequency oscillations (250-600Hz) that have been associated with epilepsy. FR are assumed to be generated in small areas of the hippocampus (1mm(3)) that contain pathologically interconnected glutamate pyramidal cell clusters. Additionally, a relation between glutamate neurotransmission and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainite (AMPA/KA) and metabotropic mGluR5 receptors is well established. Therefore, we hypothesized that antagonism of these glutamate receptors would decrease FR activity...
June 30, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/28669244/automated-detector-of-high-frequency-oscillations-in-epilepsy-based-on-maximum-distributed-peak-points
#4
Guo-Ping Ren, Jia-Qing Yan, Zhi-Xin Yu, Dan Wang, Xiao-Nan Li, Shan-Shan Mei, Jin-Dong Dai, Xiao-Li Li, Yun-Lin Li, Xiao-Fei Wang, Xiao-Feng Yang
High frequency oscillations (HFOs) are considered as biomarker for epileptogenicity. Reliable automation of HFOs detection is necessary for rapid and objective analysis, and is determined by accurate computation of the baseline. Although most existing automated detectors measure baseline accurately in channels with rare HFOs, they lose accuracy in channels with frequent HFOs. Here, we proposed a novel algorithm using the maximum distributed peak points method to improve baseline determination accuracy in channels with wide HFOs activity ranges and calculate a dynamic baseline...
April 17, 2017: International Journal of Neural Systems
https://www.readbyqxmd.com/read/28655938/significance-of-high-frequency-electrical-brain-activity
#5
REVIEW
Katsuhiro Kobayashi, Tomoyuki Akiyama, Takashi Agari, Tatsuya Sasaki, Takashi Shibata, Yoshiyuki Hanaoka, Mari Akiyama, Fumika Endoh, Makio Oka, Isao Date
 Electroencephalogram (EEG) data include broadband electrical brain activity ranging from infra-slow bands (< 0.1 Hz) to traditional frequency bands (e.g., the approx. 10 Hz alpha rhythm) to high-frequency bands of up to 500 Hz. High-frequency oscillations (HFOs) including ripple and fast ripple oscillations (80-200 Hz and>200 / 250 Hz, respectively) are particularly of note due to their very close relationship to epileptogenicity, with the possibility that they could function as a surrogate biomarker of epileptogenicity...
June 2017: Acta Medica Okayama
https://www.readbyqxmd.com/read/28644979/intraoperative-fast-ripples-independently-predict-postsurgical-epilepsy-outcome-comparison-with-other-electrocorticographic-phenomena
#6
Shaun A Hussain, Gary W Mathern, Phoebe Hung, Julius Weng, Raman Sankar, Joyce Y Wu
In the surgical management of epilepsy, the resection of cortex exhibiting interictal fast ripples (250-500Hz) on electrocorticography has been linked to postoperative seizure-freedom. Although fast ripples appear to accurately identify the epileptogenic zone-the minimum tissue that must be removed at surgery to achieve seizure-freedom-it has not been established that fast ripples are a superior biomarker in comparison with multimodal presurgical neuroimaging and other electrocorticography abnormalities. Hence, in the prediction of postoperative seizure-freedom, we compared the value of fast ripples with other intraoperative electocorticography abnormalities including focal slowing, paroxysmal fast activity, intermittent spike discharges, continuous epileptiform discharges, focal attenuation, and intraoperative seizures, as well as complete resection of the lesion defined by MRI and other neuroimaging...
June 16, 2017: Epilepsy Research
https://www.readbyqxmd.com/read/28644911/interictal-oscillations-and-focal-epileptic-disorders
#7
Maxime Lévesque, Pariya Salami, Zahra Shiri, Massimo Avoli
Neuronal network oscillations represent a main feature of the brain activity recorded in the EEG under normal and pathological conditions such as epilepsy. Specific oscillations occur between seizures in patients and in animal models of focal epilepsy, and thus they are termed interictal. According to their shape and intrinsic signal frequency, interictal oscillations are classified as spikes and high frequency oscillations (HFOs). Interictal spikes are recorded in the "wideband" EEG signal and consist of large-amplitude events that usually last less than 1 s; HFOs, in contrast, are extracted by amplifying the appropriately filtered EEG signal, and are usually categorized as ripples (80-200 Hz) and fast ripples (250-500 Hz)...
June 23, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28641116/mechanisms-for-selective-single-cell-reactivation-during-offline-sharp-wave-ripples-and-their-distortion-by-fast-ripples
#8
Manuel Valero, Robert G Averkin, Ivan Fernandez-Lamo, Juan Aguilar, Diego Lopez-Pigozzi, Jorge R Brotons-Mas, Elena Cid, Gabor Tamas, Liset Menendez de la Prida
Memory traces are reactivated selectively during sharp-wave ripples. The mechanisms of selective reactivation, and how degraded reactivation affects memory, are poorly understood. We evaluated hippocampal single-cell activity during physiological and pathological sharp-wave ripples using juxtacellular and intracellular recordings in normal and epileptic rats with different memory abilities. CA1 pyramidal cells participate selectively during physiological events but fired together during epileptic fast ripples...
June 21, 2017: Neuron
https://www.readbyqxmd.com/read/28622421/how-to-record-high-frequency-oscillations-in-epilepsy-a-practical-guideline
#9
REVIEW
Maeike Zijlmans, Gregory A Worrell, Matthias Dümpelmann, Thomas Stieglitz, Andrei Barborica, Marcel Heers, Akio Ikeda, Naotaka Usui, Michel Le Van Quyen
OBJECTIVE: Technology for localizing epileptogenic brain regions plays a central role in surgical planning. Recent improvements in acquisition and electrode technology have revealed that high-frequency oscillations (HFOs) within the 80-500 Hz frequency range provide the neurophysiologist with new information about the extent of the epileptogenic tissue in addition to ictal and interictal lower frequency events. Nevertheless, two decades after their discovery there remain questions about HFOs as biomarkers of epileptogenic brain and there use in clinical practice...
June 16, 2017: Epilepsia
https://www.readbyqxmd.com/read/28526664/effect-of-a-counseling-session-bolstered-by-text-messaging-on-self-selected-health-behaviors-in-college-students-a-preliminary-randomized-controlled-trial
#10
Janice Sandrick, Doreen Tracy, Arn Eliasson, Ashley Roth, Jeffrey Bartel, Melanie Simko, Tracy Bowman, Karen Harouse-Bell, Mariam Kashani, Marina Vernalis
BACKGROUND: The college experience is often the first time when young adults live independently and make their own lifestyle choices. These choices affect dietary behaviors, exercise habits, techniques to deal with stress, and decisions on sleep time, all of which direct the trajectory of future health. There is a need for effective strategies that will encourage healthy lifestyle choices in young adults attending college. OBJECTIVE: This preliminary randomized controlled trial tested the effect of coaching and text messages (short message service, SMS) on self-selected health behaviors in the domains of diet, exercise, stress, and sleep...
May 17, 2017: JMIR MHealth and UHealth
https://www.readbyqxmd.com/read/28521270/prediction-of-seizure-outcome-improved-by-fast-ripples-detected-in-low-noise-intraoperative-corticogram
#11
Tommaso Fedele, Georgia Ramantani, Sergey Burnos, Peter Hilfiker, Gabriel Curio, Thomas Grunwald, Niklaus Krayenbühl, Johannes Sarnthein
OBJECTIVE: Fast ripples (FR, 250-500Hz) in the intraoperative corticogram have recently been proposed as specific predictors of surgical outcome in epilepsy patients. However, online FR detection is restricted by their low signal-to-noise ratio. Here we propose the integration of low-noise EEG with unsupervised FR detection. METHODS: Pre- and post-resection ECoG (N=9 patients) was simultaneously recorded by a commercial device (CD) and by a custom-made low-noise amplifier (LNA)...
July 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28506629/hippocampal-information-processing-across-sleep-wake-cycles
#12
REVIEW
Kenji Mizuseki, Hiroyuki Miyawaki
According to a two-stage memory consolidation model, during waking theta states, afferent activity from the neocortex to the hippocampus induces transient synaptic modification in the hippocampus, where the information is deposited as a labile form of memory trace. During subsequent sharp-wave ripples (SPW-Rs), the newly acquired hippocampal information is transferred to the neocortex and stored as a long-lasting memory trace. Consistent with this hypothesis, waking theta states and SPW-Rs distinctly control information flow in the hippocampal-entorhinal loop...
May 12, 2017: Neuroscience Research
https://www.readbyqxmd.com/read/28484390/spatiotemporal-mapping-techniques-show-clozapine-impairs-neurogenic-and-myogenic-patterns-of-activity-in-the-colon-of-the-rabbit-in-a-dose-dependent-manner
#13
Susanna Every-Palmer, Roger G Lentle, Gordon Reynolds, Corrin Hulls, Paul Chambers, Helen Dunn, Pete M Ellis
Background: Clozapine, an antipsychotic used in treatment-resistant schizophrenia, has adverse gastrointestinal effects with significant associated morbidity and mortality. However, its effects on defined patterns of colonic contractile activity have not been assessed. Method: We used novel radial and longitudinal spatiotemporal mapping techniques, combined with and monitoring of ambient lumen pressure, in ex vivo preparations of triply and of singly haustrated portions of rabbit colon. We identified the contractile patterns of mass peristalses, fast phasic, and ripple contractions and directly qualified the effects of clozapine, at concentrations of 10 μmol/L, 20 μmol/L, and 30 μmol/L, and of norclozapine, the main metabolite of clozapine, on contractile patterns...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28416442/allopregnanolone-decreases-interictal-spiking-and-fast-ripples-in-an-animal-model-of-mesial-temporal-lobe-epilepsy
#14
Maxime Lévesque, Rochelle Herrington, Leila Leclerc, Michael A Rogawski, Massimo Avoli
The objective of this study was to characterize the impact of allopregnanolone, a neurosteroid that acts as a positive allosteric modulator of synaptic and extrasynaptic GABAA receptors, on interictal spikes and high-frequency oscillations (ripples: 80-200 Hz, fast ripples: 250-500 Hz) in the pilocarpine model of mesial temporal lobe epilepsy. Seven out of 25 Sprague-Dawley rats experiencing 1 h of pilocarpine-induced status epilepticus (SE) began treatment with allopregnanolone (9.6-12.8 mg/kg/day) on the following day...
April 15, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28412559/interictal-ripples-nested-in-epileptiform-discharge-help-to-identify-the-epileptogenic-zone-in-neocortical-epilepsy
#15
Shuang Wang, Norman K So, Bo Jin, Irene Z Wang, Juan C Bulacio, Rei Enatsu, Shenyi Dai, Zhong Chen, Jorge Gonzalez-Martinez, Imad M Najm
OBJECTIVE: This study aimed to identify the subtype of interictal ripples that help delineate the epileptogenic zone in neocortical epilepsy. METHODS: Totally 25 patients with focal neocortical epilepsy who had invasive electroencephalography (EEG) evaluation and subsequent surgery were included. They were followed up for at least 2years. Interictal ripples (80-250Hz) and fast ripples (250-500Hz) during slow-wave sleep were identified. Neocortical ripples were defined as type I ripples when they were superimposed on epileptiform discharges, and as type II ripples when they occurred independently...
June 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28382952/parvalbumin-expressing-interneurons-coordinate-hippocampal-network-dynamics-required-for-memory-consolidation
#16
Nicolette Ognjanovski, Samantha Schaeffer, Jiaxing Wu, Sima Mofakham, Daniel Maruyama, Michal Zochowski, Sara J Aton
Activity in hippocampal area CA1 is essential for consolidating episodic memories, but it is unclear how CA1 activity patterns drive memory formation. We find that in the hours following single-trial contextual fear conditioning (CFC), fast-spiking interneurons (which typically express parvalbumin (PV)) show greater firing coherence with CA1 network oscillations. Post-CFC inhibition of PV+ interneurons blocks fear memory consolidation. This effect is associated with loss of two network changes associated with normal consolidation: (1) augmented sleep-associated delta (0...
April 6, 2017: Nature Communications
https://www.readbyqxmd.com/read/28380659/tailoring-epilepsy-surgery-with-fast-ripples-in-the-intraoperative-electrocorticogram
#17
Maryse A van 't Klooster, Nicole E C van Klink, Willemiek J E M Zweiphenning, Frans S S Leijten, Rina Zelmann, Cyrille H Ferrier, Peter C van Rijen, Willem M Otte, Kees P J Braun, Geertjan J M Huiskamp, Maeike Zijlmans
OBJECTIVE: Intraoperative electrocorticography (ECoG) can be used to delineate the resection area in epilepsy surgery. High-frequency oscillations (HFOs; 80-500 Hz) seem better biomarkers for epileptogenic tissue than spikes. We studied how HFOs and spikes in combined pre- and postresection ECoG predict surgical outcome in different tailoring approaches. METHODS: We, retrospectively, marked HFOs, divided into fast ripples (FRs; 250-500 Hz) and ripples (80-250 Hz), and spikes in pre- and postresection ECoG sampled at 2,048 Hz in people with refractory focal epilepsy...
May 2017: Annals of Neurology
https://www.readbyqxmd.com/read/28337411/physiological-and-pathological-high-frequency-oscillations-have-distinct-sleep-homeostatic-properties
#18
Nicolás von Ellenrieder, François Dubeau, Jean Gotman, Birgit Frauscher
OBJECTIVE: The stage of sleep is a known modulator of high-frequency oscillations (HFOs). For instance, high amplitude slow waves during NREM sleep and the subtypes of REM sleep were shown to contribute to a better separation between physiological and pathological HFOs. This study investigated rates and spatial spread of the different HFO types (physiological and pathological ripples in the 80-250 Hz frequency band, and fast ripples above 250 Hz) depending on time spent in sleep across the different sleep cycles...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28268496/computational-modeling-of-high-frequency-oscillations-recorded-with-clinical-intracranial-macroelectrodes
#19
M Shamas, P Benquet, I Merlet, W El Falou, M Khalil, F Wendling
High Frequency Oscillations (HFOs) are a potential biomarker of epileptogenic regions. They have been extensively investigated in terms of automatic detection, classification and feature extraction. However, the mechanisms governing the generation of HFOs as well as the observability conditions on clinical intracranial macroelectrodes remain elusive. In this paper, we propose a novel physiologically-relevant macroscopic model for accurate simulation of HFOs as invasively recorded in epileptic patients. This model accounts for both the temporal and spatial properties of the cortical patch at the origin of epileptiform activity...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28258937/evoked-versus-spontaneous-high-frequency-oscillations-in-the-chronic-electrocorticogram-in-focal-epilepsy
#20
M A van 't Klooster, N E C van Klink, D van Blooijs, C H Ferrier, K P J Braun, F S S Leijten, G J M Huiskamp, M Zijlmans
OBJECTIVE: Spontaneous high frequency oscillations (HFOs; ripples 80-250Hz, fast ripples (FRs) 250-500Hz) are biomarkers for epileptogenic tissue in focal epilepsy. Single pulse electrical stimulation (SPES) can evoke HFOs. We hypothesized that stimulation distinguishes pathological from physiological ripples and compared the occurrence of evoked and spontaneous HFOs within the seizure onset zone (SOZ) and eloquent functional areas. METHODS: Ten patients underwent SPES during 2048Hz electrocorticography (ECoG)...
May 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
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