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HIgh Frequency Oscillation

Min Wu, Ting Wan, Xiongbo Wan, Yuxiao Du, Jinhua She
This letter describes the improvement of two methods of detecting high-frequency oscillations (HFO) and their use to localize epileptic seizure onset zones (SOZs). The wavelet transform (WT) method was improved by combining the complex Morlet WT with Shannon entropy to enhance the temporal-frequency resolution during HFO detection. And the matching pursuit (MP) method was improved by combining it with an adaptive genetic algorithm to improve the speed and accuracy of the calculations for HFO detection. The HFOs detected by these two methods were used to localize SOZs in five patients...
October 20, 2016: Neural Computation
Duo Sheng, Min-Rong Hong
This paper presents an all-digital low-power oscillator for reference clocks in wireless body area network (WBAN) applications. The proposed on-chip complementary metal-oxide-semiconductor (CMOS) oscillator provides low-frequency clock signals with low power consumption, high delay resolution, and low circuit complexity. The cascade-stage structure of the proposed design simultaneously achieves high resolution and a wide frequency range. The proposed hysteresis delay cell further reduces the power consumption and hardware costs by 92...
October 14, 2016: Sensors
Nicola Rossi, Floris R Braakman, Davide Cadeddu, Denis Vasyukov, Gözde Tütüncüoglu, Anna Fontcuberta I Morral, Martino Poggio
Self-assembled nanowire (NW) crystals can be grown into nearly defect-free nanomechanical resonators with exceptional properties, including small motional mass, high resonant frequency and low dissipation. Furthermore, by virtue of slight asymmetries in geometry, a NW's flexural modes are split into doublets oscillating along orthogonal axes. These characteristics make bottom-up grown NWs extremely sensitive vectorial force sensors. Here, taking advantage of its adaptability as a scanning probe, we use a single NW to image a sample surface...
October 17, 2016: Nature Nanotechnology
Jae W Chung, Edward Ofori, Gaurav Misra, Christopher W Hess, David E Vaillancourt
: Accurate motor performance may depend on the scaling of distinct oscillatory activity within the motor cortex and effective neural communication between the motor cortex and other brain areas. Oscillatory activity within the beta-band (13-30Hz) has been suggested to provide distinct functional roles for attention and sensorimotor control, yet it remains unclear how beta-band and other oscillatory activity within and between cortical regions is coordinated to enhance motor performance...
October 13, 2016: NeuroImage
Dan Denis, Richard Rowe, A Mark Williams, Elizabeth Milne
The human mirror neuron system is believed to play an important role in facilitating the ability of athletes to anticipate the actions of an opponent. This system is often assessed with EEG by measuring event-related changes in mu (8-13Hz) sensorimotor oscillations. However, traditional channel-based analyses of this measure are flawed in that due to volume conduction effects mu and non-mu alpha activity can become mixed. This flaw means it is unclear the extent to which mu activity indexes the mirror system, as opposed to other processes such as attentional demand...
October 13, 2016: NeuroImage
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...
October 12, 2016: Neuron
Ottó Dócs, Katalin Hegyi, Attila Mokánszky, Anikó Mónusné, Lívia Beke, Csilla András, Judit Bedekovics, Gábor Méhes
Mutation rates determined by allele-specific PCR can be highly different in KRAS exon 2 mutant colorectal carcinoma (CRC) samples suggesting intratumoural heterogeneity. To address the effect of KRAS gene copy number on the relative mutant allele frequency the KRAS locus was individually quantified following FISH analysis in 36 cases. We observed, that mutant KRAS status was associated with an elevated KRAS locus number (2.36 ± 0.42 vs 2.63 ± 0.75; p = 0.037) reflecting an increased aneuploidy status but no true amplification of the locus...
October 15, 2016: Pathology Oncology Research: POR
Bethany Lusch, Pedro D Maia, J Nathan Kutz
Determining the interactions and causal relationships between nodes in an unknown networked dynamical system from measurement data alone is a challenging, contemporary task across the physical, biological, and engineering sciences. Statistical methods, such as the increasingly popular Granger causality, are being broadly applied for data-driven discovery of connectivity in fields from economics to neuroscience. A common version of the algorithm is called pairwise-conditional Granger causality, which we systematically test on data generated from a nonlinear model with known causal network structure...
September 2016: Physical Review. E
J Hizanidis, N Lazarides, G P Tsironis
We report on the emergence of robust multiclustered chimera states in a dissipative-driven system of symmetrically and locally coupled identical superconducting quantum interference device (SQUID) oscillators. The "snakelike" resonance curve of the single SQUID is the key to the formation of the chimera states and is responsible for the extreme multistability exhibited by the coupled system that leads to attractor crowding at the geometrical resonance (inductive-capacitive) frequency. Until now, chimera states were mostly believed to exist for nonlocal coupling...
September 2016: Physical Review. E
Jinjie Zhu, Chen Kong, Xianbin Liu
We study the subthreshold and suprathreshold vibrational resonance in the FitzHugh-Nagumo neuron model. For the subthreshold situation, two cases where the stationary states are equilibrium point and limit cycle are considered, where different natures of vibrational resonance are observed via theoretical and numerical methods. Especially when the frequency of the high-frequency driving force is near the so-called canard-resonance frequency, the firing rate can be significantly enhanced at the presence of noise...
September 2016: Physical Review. E
Jian Deng, Lubao Teng, C P Caulfield, Xuerui Mao
We propose a natural model to probe in a controlled fashion the instability of interacting vortex rings shed from the edge of an oblate spheroid disk of major diameter c, undergoing oscillations of frequency f_{0} and amplitude A. We perform a Floquet stability analysis to determine the characteristics of the instability modes, which depend strongly on the azimuthal (integer) wave number m. We vary two key control parameters, the Keulegan-Carpenter number K_{C}=2πA/c and the Stokes number β=f_{0}c^{2}/ν, where ν is the kinematic viscosity of the fluid...
September 2016: Physical Review. E
Hannah Bos, Markus Diesmann, Moritz Helias
Oscillations are omnipresent in neural population signals, like multi-unit recordings, EEG/MEG, and the local field potential. They have been linked to the population firing rate of neurons, with individual neurons firing in a close-to-irregular fashion at low rates. Using a combination of mean-field and linear response theory we predict the spectra generated in a layered microcircuit model of V1, composed of leaky integrate-and-fire neurons and based on connectivity compiled from anatomical and electrophysiological studies...
October 2016: PLoS Computational Biology
Masashi Mikamo, Tomoyuki Fujisawa, Yoshiyuki Oyama, Masato Kono, Noriyuki Enomoto, Yutaro Nakamura, Naoki Inui, Hiromitsu Sumikawa, Takeshi Johkoh, Takafumi Suda
PURPOSE: Small airway disease (SAWD) in patients with interstitial lung disease (ILD) is often assessed by high-resolution computed tomography (HRCT). However, frequent HRCT examinations result in a high level of radiographic exposure. This study investigated the utility of the forced oscillation technique (FOT) to evaluate SAWD in patients with ILD. METHODS: Broadband FOT using a commercially available device (MostGraph-01) and pulmonary function tests (PFT) were performed in 90 patients with ILD...
October 12, 2016: Lung
Joohi Jimenez-Shahed, Ilknur Telkes, Ashwin Viswanathan, Nuri F Ince
Background: Deep brain stimulation (DBS) is an emerging treatment strategy for severe, medication-refractory Tourette syndrome (TS). Thalamic (Cm-Pf) and pallidal (including globus pallidus interna, GPi) targets have been the most investigated. While the neurophysiological correlates of Parkinson's disease (PD) in the GPi and subthalamic nucleus (STN) are increasingly recognized, these patterns are not well characterized in other disease states. Recent findings indicate that the cross-frequency coupling (CFC) between beta band and high frequency oscillations (HFOs) within the STN in PD patients is pathologic...
2016: Frontiers in Neuroscience
Laura D Lewis, Kawin Setsompop, Bruce R Rosen, Jonathan R Polimeni
Oscillatory neural dynamics play an important role in the coordination of large-scale brain networks. High-level cognitive processes depend on dynamics evolving over hundreds of milliseconds, so measuring neural activity in this frequency range is important for cognitive neuroscience. However, current noninvasive neuroimaging methods are not able to precisely localize oscillatory neural activity above 0.2 Hz. Electroencephalography and magnetoencephalography have limited spatial resolution, whereas fMRI has limited temporal resolution because it measures vascular responses rather than directly recording neural activity...
October 11, 2016: Proceedings of the National Academy of Sciences of the United States of America
K Kessler, R A Seymour, G Rippon
Although atypical social behaviour remains a key characterisation of ASD, the presence of sensory and perceptual abnormalities has been given a more central role in recent classification changes. An understanding of the origins of such aberrations could thus prove a fruitful focus for ASD research. Early neurocognitive models of ASD suggested that the study of high frequency activity in the brain as a measure of cortical connectivity might provide the key to understanding the neural correlates of sensory and perceptual deviations in ASD...
October 5, 2016: Neuroscience and Biobehavioral Reviews
Jacob P Keller, Loren L Looger
Transmembrane transporter proteins allow the passage of essentially all biologically important molecules across the lipid membranes of cells and organelles and are therefore of central importance to all forms of life. Current methods of transporter measurement, however, are lacking in several dimensions. Herein, a method is presented in which oscillating stimuli are presented to transporter-expressing cells, and activity is measured through imaging the corresponding oscillating responses of intracellular fluorescent sensors...
October 6, 2016: Molecular Cell
H S Wong, S K He, H J Chung, M S Zhang, Kelvin Cher, Melvin Low, T J Zhou, Y Yang, S K Wong
Replacing Ir with Rh in a CoIr system possessing negative uniaxial magnetocrystalline anisotropy (K u ) substantially reduces its magnetic damping and coercivity by more than half while retaining its high negative K u . Moreover, a higher saturation magnetization (M s ) and more isotropic coercivity are achieved. Such material development makes it particularly suitable for use as the soft underlayer (SUL) of magnetic recording media for reducing noise, and as the oscillation layer of a spin-torque oscillator (STO) for achieving higher oscillation frequency, larger AC magnetic field and lower driving current, which can be readily integrated with the current recording head for microwave-assisted magnetic recording...
November 11, 2016: Nanotechnology
Stephen V Gliske, William C Stacey, Eugene Lim, Katherine A Holman, Christian G Fink
Previous experimental studies have demonstrated the emergence of narrowband local field potential oscillations during epileptic seizures in which the underlying neural activity appears to be completely asynchronous. We derive a mathematical model explaining how this counterintuitive phenomenon may occur, showing that a population of independent, completely asynchronous neurons may produce narrowband oscillations if each neuron fires quasi-periodically, without requiring any intrinsic oscillatory cells or feedback inhibition...
July 14, 2016: International Journal of Neural Systems
Maximilian Albert, Marijan Beg, Dmitri Chernyshenko, Marc-Antonio Bisotti, Rebecca L Carey, Hans Fangohr, Peter J Metaxas
Using finite element micromagnetic simulations, we study how resonant magnetisation dynamics in thin magnetic discs with perpendicular anisotropy are influenced by magnetostatic coupling to a magnetic nanoparticle. We identify resonant modes within the disc using direct magnetic eigenmode calculations and study how their frequencies and spatial profiles are changed by the nanoparticle's stray magnetic field. We demonstrate that particles can generate shifts in the resonant frequency of the disc's fundamental mode which exceed resonance linewidths in recently studied spin torque oscillator devices...
November 11, 2016: Nanotechnology
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