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https://www.readbyqxmd.com/read/30318350/hexadirectional-modulation-of-theta-power-in-human-entorhinal-cortex-during-spatial-navigation
#1
Dong Chen, Lukas Kunz, Wenjing Wang, Hui Zhang, Wen-Xu Wang, Andreas Schulze-Bonhage, Peter C Reinacher, Wenjing Zhou, Shuli Liang, Nikolai Axmacher, Liang Wang
Grid cells and theta oscillations are fundamental components of the brain's navigation system. Grid cells provide animals [1, 2] and humans [3, 4] with a spatial map of the environment by exhibiting multiple firing fields arranged in a regular grid of equilateral triangles. This unique firing pattern presumably constitutes the neural basis for path integration [5-8] and may also enable navigation in visual and conceptual spaces [9-12]. Theta frequency oscillations are a prominent mesoscopic network phenomenon during navigation in both rodents and humans [13, 14] and encode movement speed [15-17], distance traveled [18], and proximity to spatial boundaries [19]...
September 14, 2018: Current Biology: CB
https://www.readbyqxmd.com/read/30302390/adaptation-and-inhibition-control-pathological-synchronization-in-a-model-of-focal-epileptic-seizure
#2
Anatoly Buchin, Cliff C Kerr, Gilles Huberfeld, Richard Miles, Boris Gutkin
Pharmacoresistant epilepsy is a common neurological disorder in which increased neuronal intrinsic excitability and synaptic excitation lead to pathologically synchronous behavior in the brain. In the majority of experimental and theoretical epilepsy models, epilepsy is associated with reduced inhibition in the pathological neural circuits, yet effects of intrinsic excitability are usually not explicitly analyzed. Here we present a novel neural mass model that includes intrinsic excitability in the form of spike-frequency adaptation in the excitatory population...
September 2018: ENeuro
https://www.readbyqxmd.com/read/30291240/electrophysiological-mechanisms-of-human-memory-consolidation
#3
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
https://www.readbyqxmd.com/read/30250863/physiological-and-pathological-high-frequency-oscillations-in-focal-epilepsy
#4
Jan Cimbalnik, Benjamin Brinkmann, Vaclav Kremen, Pavel Jurak, Brent Berry, Jamie Van Gompel, Matt Stead, Greg Worrell
Objective: This study investigates high-frequency oscillations (HFOs; 65-600 Hz) as a biomarker of epileptogenic brain and explores three barriers to their clinical translation: (1) Distinguishing pathological HFOs (pathHFO) from physiological HFOs (physHFO). (2) Classifying tissue under individual electrodes as epileptogenic (3) Reproducing results across laboratories. Methods: We recorded HFOs using intracranial EEG (iEEG) in 90 patients with focal epilepsy and 11 patients without epilepsy...
September 2018: Annals of Clinical and Translational Neurology
https://www.readbyqxmd.com/read/30242045/theta-bursts-precede-and-spindles-follow-cortical-and-thalamic-downstates-in-human-nrem-sleep
#5
Chris Gonzalez, Rachel Mak-McCully, Burke Rosen, Sydney S Cash, Patrick Chauvel, Hélène Bastuji, Marc Rey, Eric Halgren
Since their discovery, slow oscillations have been observed to group spindles during non-REM sleep. Previous studies assert that the slow oscillation downstate (DS) is preceded by slow spindles (10-12Hz), and followed by fast spindles (12-16Hz). Here, using both direct transcortical recordings in patients with intractable epilepsy (n=10, 8 female), as well as scalp EEG recordings from a healthy cohort (n=3, 1 female), we find in multiple cortical areas that both slow and fast spindles follow the DS. Although discrete oscillations do precede DSs, they are theta bursts (TB) centered at 5-8Hz...
September 21, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/30216929/ripple-oscillations-in-the-left-temporal-neocortex-are-associated-with-impaired-verbal-episodic-memory-encoding
#6
Zachary J Waldman, Liliana Camarillo-Rodriguez, Inna Chervenova, Brent Berry, Shoichi Shimamoto, Bahareh Elahian, Michal Kucewicz, Chaitanya Ganne, Xiao-Song He, Leon A Davis, Joel Stein, Sandhitsu Das, Richard Gorniak, Ashwini D Sharan, Robert Gross, Cory S Inman, Bradley C Lega, Kareem Zaghloul, Barbara C Jobst, Katheryn A Davis, Paul Wanda, Mehraneh Khadjevand, Joseph Tracy, Daniel S Rizzuto, Gregory Worrell, Michael Sperling, Shennan A Weiss
BACKGROUND: We sought to determine if ripple oscillations (80-120 Hz), detected in intracranial electroencephalogram (iEEG) recordings of patients with epilepsy, correlate with an enhancement or disruption of verbal episodic memory encoding. METHODS: We defined ripple and spike events in depth iEEG recordings during list learning in 107 patients with focal epilepsy. We used logistic regression models (LRMs) to investigate the relationship between the occurrence of ripple and spike events during word presentation and the odds of successful word recall following a distractor epoch and included the seizure onset zone (SOZ) as a covariate in the LRMs...
September 11, 2018: Epilepsy & Behavior: E&B
https://www.readbyqxmd.com/read/30210311/alterations-of-coherent-theta-and-gamma-network-oscillations-as-an-early-biomarker-of-temporal-lobe-epilepsy-and-alzheimer-s-disease
#7
REVIEW
Valentina F Kitchigina
Alzheimer's disease (AD) and temporal lobe epilepsy (TLE) are the most common forms of neurodegenerative disorders characterized by the loss of cells and progressive irreversible alteration of cognitive functions, such as attention and memory. AD may be an important cause of epilepsy in the elderly. Early diagnosis of diseases is very important for their successful treatment. Many efforts have been done for defining new biomarkers of these diseases. Significant advances have been made in the searching of some AD and TLE reliable biomarkers, including cerebrospinal fluid and plasma measurements and glucose positron emission tomography...
2018: Frontiers in Integrative Neuroscience
https://www.readbyqxmd.com/read/30197086/direct-electrophysiological-evidence-for-prefrontal-control-of-hippocampal-processing-during-voluntary-forgetting
#8
Carina R Oehrn, Juergen Fell, Conrad Baumann, Timm Rosburg, Eva Ludowig, Henrik Kessler, Simon Hanslmayr, Nikolai Axmacher
Forgetting does not necessarily reflect failure to encode information but can, to some extent, also be voluntarily controlled. Previous studies have suggested that voluntary forgetting relies on active inhibition of encoding processes in the hippocampus by the dorsolateral prefrontal cortex (DLPFC) [1-4]. During attentional and sensorimotor processing, enhanced DLPFC theta power alongside increased alpha/beta oscillations are a neural signature of an inhibitory top-down mechanism, with theta oscillations reflecting prefrontal control and alpha/beta oscillations occurring in areas targeted by inhibition [5-12]...
September 24, 2018: Current Biology: CB
https://www.readbyqxmd.com/read/30180641/chaos-in-homeostatically-regulated-neural-systems
#9
Wilten Nicola, Peter John Hellyer, Sue Ann Campbell, Claudia Clopath
Low-dimensional yet rich dynamics often emerge in the brain. Examples include oscillations and chaotic dynamics during sleep, epilepsy, and voluntary movement. However, a general mechanism for the emergence of low dimensional dynamics remains elusive. Here, we consider Wilson-Cowan networks and demonstrate through numerical and analytical work that homeostatic regulation of the network firing rates can paradoxically lead to a rich dynamical repertoire. The dynamics include mixed-mode oscillations, mixed-mode chaos, and chaotic synchronization when the homeostatic plasticity operates on a moderately slower time scale than the firing rates...
August 2018: Chaos
https://www.readbyqxmd.com/read/30176615/decision-support-system-for-seizure-onset-zone-localization-based-on-channel-ranking-and-high-frequency-eeg-activity
#10
Stefan L Sumsky, Sabato Santaniello
Interictal high frequency oscillations (HFO) are a promising biomarker that can help define the seizure onset zone (SOZ) and predict the surgical outcome after the epilepsy surgery. The utility of HFO in planning the surgery, though, is un-clear. Reasons include the variability of the HFO across patients and brain regions and the influence of the sleep-wake cycle, which causes large fluctuations in the ratio be-tween the HFO observed in SOZ and non-SOZ regions. To cope with these limitations, a rank-based solution is pro-posed to identify the SOZ by using the HFO in multi-channel intracranial EEG...
August 30, 2018: IEEE Journal of Biomedical and Health Informatics
https://www.readbyqxmd.com/read/30169677/anticonvulsant-and-neuroprotective-effects-of-cannabidiol-during-the-juvenile-period
#11
Linda K Friedman, Joann P Wongvravit
Anticonvulsant effects of cannabidiol (CBD), a nonpsychoactive cannabinoid, have not been investigated in the juvenile brain. We hypothesized that CBD would attenuate epileptiform activity at an age when the brain first becomes vulnerable to neurotoxicity and social/cognitive impairments. To induce seizures, kainic acid (KA) was injected either into the hippocampus (KAih) or systemically (KAip) on postnatal (P) day 20. CBD was coadministered (KA + CBDih, KA + CBDip) or injected 30 minutes postseizure onset (KA/CBDih, KA/CBDip)...
October 1, 2018: Journal of Neuropathology and Experimental Neurology
https://www.readbyqxmd.com/read/30144079/synaptic-entrainment-of-ectopic-action-potential-generation-in-hippocampal-pyramidal-neurons
#12
Christian Thome, Fabian C Roth, Joshua Obermayer, Antonio Yanez, Andreas Draguhn, Alexei V Egorov
KEY POINTS: Ectopic action potentials (EAPs) arise at distal locations in axonal fibres and are often associated with neuronal pathologies such as epilepsy or nerve injury, but they also occur during physiological network conditions. This study investigates whether initiation of such EAPs is modulated by subthreshold synaptic activity. Somatic subthreshold potentials invade the axonal compartment to considerable distances (>350 μm), whereas spread of axonal subthreshold potentials to the soma is inefficient...
August 24, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/30140078/epileptic-high-frequency-oscillations-in-scalp-electroencephalography
#13
REVIEW
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
https://www.readbyqxmd.com/read/30120133/removing-high-frequency-oscillations-a-prospective-multicenter-study-on-seizure-outcome
#14
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
https://www.readbyqxmd.com/read/30116220/rhythms-of-core-clock-genes-and-spontaneous-locomotor-activity-in-post-status-epilepticus-model-of-mesial-temporal-lobe-epilepsy
#15
Heloisa de Carvalho Matos, Bruna Del Vechio Koike, Wanessa Dos Santos Pereira, Tiago G de Andrade, Olagide W Castro, Marcelo Duzzioni, Maheedhar Kodali, Joao P Leite, Ashok K Shetty, Daniel L G Gitaí
The interaction of Mesial Temporal Lobe Epilepsy (mTLE) with the circadian system control is apparent from an oscillatory pattern of limbic seizures, daytime's effect on seizure onset and the efficacy of antiepileptic drugs. Moreover, seizures per se can interfere with the biological rhythm output, including circadian oscillation of body temperature, locomotor activity, EEG pattern as well as the transcriptome. However, the molecular mechanisms underlying this cross-talk remain unclear. In this study, we systematically evaluated the temporal expression of seven core circadian transcripts ( Bmal1, Clock, Cry1, Cry2, Per1, Per2 , and Per3 ) and the spontaneous locomotor activity (SLA) in post- status epilepticus (SE) model of mTLE...
2018: Frontiers in Neurology
https://www.readbyqxmd.com/read/30115601/negative-effects-of-interictal-spikes-on-theta-rhythm-in-human-temporal-lobe-epilepsy
#16
Xiaoxuan Fu, Youhua Wang, Manling Ge, Danhong Wang, Rongguang Gao, Long Wang, Jundan Guo, Hesheng Liu
Interictal spike is a biomarker of epilepsy that can occur frequently between seizures. Its potential effects on brain oscillations, especially on theta rhythm (4-8 Hz) that is related to a variety of cognitive processes, remain controversial. Using local field potentials recorded from patients with temporal lobe epilepsy (TLE), we investigated here the impact of spikes on theta rhythm immediately after spikes and during the prolonged periods (lasting 4-36 s) between adjacent spikes. Local field potentials (LFPs) were recorded in different epileptogenic areas including the anterior hippocampus (aH) and the entorhinal cortex (EC) as well as in the extended propagation pathway...
August 13, 2018: Epilepsy & Behavior: E&B
https://www.readbyqxmd.com/read/30096484/lithium-affects-rat-hippocampal-electrophysiology-and-epileptic-seizures-in-a-dose-dependent-manner
#17
Guohui Jiang, Tianqiang Pu, Zhimin Li, Xiaodong Zhang, Ruijiao Zhou, Xing Cao, Juming Yu, Xiaoming Wang
Lithium, a classic mood stabilizer, prevents apoptosis-dependent cellular death and has garnered considerable interest as a neuroprotective agent that is efficacious in the treatment of many neurological diseases. However, the effects of lithium in epilepsy remain controversial. We found that different doses of lithium affect epileptic seizure activity and bidirectionally modulate the susceptibility to and severity of seizures induced by pilocarpine in rats. Recently, it has been demonstrated that systematically administered lithium affects the powers of hippocampal gamma and theta oscillations in baseline electroencephalograms...
October 2018: Epilepsy Research
https://www.readbyqxmd.com/read/30077870/visually-validated-semi-automatic-high-frequency-oscillation-detection-aides-the-delineation-of-epileptogenic-regions-during-intra-operative-electrocorticography
#18
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
https://www.readbyqxmd.com/read/30057733/link-prediction-investigation-of-dynamic-information-flow-in-epilepsy
#19
Yan He, Fan Yang, Yunli Yu, Celso Grebogi
As a brain disorder, epilepsy is characterized with abnormal hypersynchronous neural firings. It is known that seizures initiate and propagate in different brain regions. Long-term intracranial multichannel electroencephalography (EEG) reflects broadband ictal activity under seizure occurrence. Network-based techniques are efficient in discovering brain dynamics and offering finger-print features for specific individuals. In this study, we adopt link prediction for proposing a novel workflow aiming to quantify seizure dynamics and uncover pathological mechanisms of epilepsy...
2018: Journal of Healthcare Engineering
https://www.readbyqxmd.com/read/30051505/high-frequency-oscillations-in-the-normal-human-brain
#20
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
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