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Phase amplitude coupling

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https://www.readbyqxmd.com/read/28441393/sequence-learning-modulates-neural-responses-and-oscillatory-coupling-in-human-and-monkey-auditory-cortex
#1
Yukiko Kikuchi, Adam Attaheri, Benjamin Wilson, Ariane E Rhone, Kirill V Nourski, Phillip E Gander, Christopher K Kovach, Hiroto Kawasaki, Timothy D Griffiths, Matthew A Howard, Christopher I Petkov
Learning complex ordering relationships between sensory events in a sequence is fundamental for animal perception and human communication. While it is known that rhythmic sensory events can entrain brain oscillations at different frequencies, how learning and prior experience with sequencing relationships affect neocortical oscillations and neuronal responses is poorly understood. We used an implicit sequence learning paradigm (an "artificial grammar") in which humans and monkeys were exposed to sequences of nonsense words with regularities in the ordering relationships between the words...
April 2017: PLoS Biology
https://www.readbyqxmd.com/read/28430436/time-domain-thz-spectroscopy-reveals-coupled-protein-hydration-dielectric-response-in-solutions-of-native-and-fibrils-of-human-lysozyme
#2
Fabio Novelli, Saeideh Ostovar Pour, Jonathan O Tollerud, Ashkan Roozbeh, Dominique R T Appadoo, Ewan W Blanch, Jeffrey A Davis
Here we reveal details of the interaction between human lysozyme proteins, both native and fibrils, and their water environment by intense terahertz time domain spectroscopy. With the aid of a rigorous dielectric model, we determine the amplitude and phase of the oscillating dipole induced by the THz field in the volume containing the protein and its hydration water. At low concentrations, the amplitude of this induced dipolar response decreases with increasing concentration. Beyond a certain threshold, marking the onset of the interactions between the extended hydration shells, the amplitude remains fixed but the phase of the induced dipolar response, which is initially in phase with the applied THz field, begins to change...
April 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28429783/fine-structure-of-the-topological-defect-cores-studied-for-disclinations-in-lyotropic-chromonic-liquid-crystals
#3
Shuang Zhou, Sergij V Shiyanovskii, Heung-Shik Park, Oleg D Lavrentovich
The detailed structure of singularities of ordered field represents a fundamental problem in diverse areas of physics. At the defect cores, the deformations are so strong that the system explores states with symmetry different from that of an undistorted material. These regions are difficult to explore experimentally as their spatial extension is very small, a few molecular lengths in the condensed matter. Here we explore the cores of disclinations in the so-called chromonic nematics that extend over macroscopic length scales accessible for optical characterization...
April 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28424606/bifurcation-analysis-on-phase-amplitude-cross-frequency-coupling-in-neural-networks-with-dynamic-synapses
#4
Takumi Sase, Yuichi Katori, Motomasa Komuro, Kazuyuki Aihara
We investigate a discrete-time network model composed of excitatory and inhibitory neurons and dynamic synapses with the aim at revealing dynamical properties behind oscillatory phenomena possibly related to brain functions. We use a stochastic neural network model to derive the corresponding macroscopic mean field dynamics, and subsequently analyze the dynamical properties of the network. In addition to slow and fast oscillations arising from excitatory and inhibitory networks, respectively, we show that the interaction between these two networks generates phase-amplitude cross-frequency coupling (CFC), in which multiple different frequency components coexist and the amplitude of the fast oscillation is modulated by the phase of the slow oscillation...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28424599/electrophysiological-sequelae-of-hemispherotomy-in-ipsilateral-human-cortex
#5
Ammar H Hawasli, Ravi Chacko, Nicholas P Szrama, David T Bundy, Mrinal Pahwa, Chester K Yarbrough, Brian J Dlouhy, David D Limbrick, Dennis L Barbour, Matthew D Smyth, Eric C Leuthardt
Objectives: Hemispheric disconnection has been used as a treatment of medically refractory epilepsy and evolved from anatomic hemispherectomy to functional hemispherectomies to hemispherotomies. The hemispherotomy procedure involves disconnection of an entire hemisphere with limited tissue resection and is reserved for medically-refractory epilepsy due to diffuse hemispheric disease. Although it is thought to be effective by preventing seizures from spreading to the contralateral hemisphere, the electrophysiological effects of a hemispherotomy on the ipsilateral hemisphere remain poorly defined...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28424297/magnitude-and-behavior-of-cross-talk-effects-in-multi-channel-electrophysiology-experiments
#6
Matthew John Nelson, Silvana Valtcheva, Laurent Venance
Modern neurophysiological experiments frequently involve multiple channels separated by very small distances. A unique methodological concern for multiple electrode experiments is that of capacitive coupling (cross-talk) between channels. Yet the nature of the cross-talk recording circuit is not well known in the field and the extent to which it practically affects neurophysiology experiments has never been fully investigated. Here we describe a simple electrical circuit model of simultaneous recording and stimulation with two or more channels and experimentally verify the model using ex vivo brain slice and in vivo whole-brain preparations...
April 19, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28416595/nonsinusoidal-beta-oscillations-reflect-cortical-pathophysiology-in-parkinson-s-disease
#7
Scott R Cole, Roemer van der Meij, Erik J Peterson, Coralie de Hemptinne, Philip A Starr, Bradley Voytek
Oscillations in neural activity play a critical role in neural computation and communication. There is intriguing new evidence that the nonsinusoidal features of the oscillatory waveforms may inform underlying physiological and pathophysiological characteristics. Time-domain waveform analysis approaches stand in contrast to traditional Fourier-based methods, which alter or destroy subtle waveform features. Recently it has been shown that the waveform features of oscillatory beta (13-30 Hz) events-a prominent motor cortical oscillation-may reflect near-synchronous excitatory synaptic inputs onto cortical pyramidal neurons...
April 17, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28401931/early-neurovascular-dysfunction-in-a-transgenic-rat-model-of-alzheimer-s-disease
#8
Illsung L Joo, Aaron Y Lai, Paolo Bazzigaluppi, Margaret M Koletar, Adrienne Dorr, Mary E Brown, Lynsie A M Thomason, John G Sled, JoAnne McLaurin, Bojana Stefanovic
Alzheimer's disease (AD), pathologically characterized by amyloid-β peptide (Aβ) accumulation, neurofibrillary tangle formation, and neurodegeneration, is thought to involve early-onset neurovascular abnormalities. Hitherto studies on AD-associated neurovascular injury have used animal models that exhibit only a subset of AD-like pathologies and demonstrated some Aβ-dependent vascular dysfunction and destabilization of neuronal network. The present work focuses on the early stage of disease progression and uses TgF344-AD rats that recapitulate a broader repertoire of AD-like pathologies to investigate the cerebrovascular and neuronal network functioning using in situ two-photon fluorescence microscopy and laminar array recordings of local field potentials, followed by pathological analyses of vascular wall morphology, tau hyperphosphorylation, and amyloid plaques...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28400257/phase-amplitude-coupled-persistent-theta-and-gamma-oscillations-in-rat-primary-motor-cortex-in%C3%A2-vitro
#9
Nicholas W Johnson, Mazhar Özkan, Adrian P Burgess, Emma J Prokic, Keith A Wafford, Michael J O'Neill, Stuart D Greenhill, Ian M Stanford, Gavin L Woodhall
In vivo, theta (4-7 Hz) and gamma (30-80 Hz) neuronal network oscillations are known to coexist and display phase-amplitude coupling (PAC). However, in vitro, these oscillations have for many years been studied in isolation. Using an improved brain slice preparation technique we have, using co-application of carbachol (10 μM) and kainic acid (150 nM), elicited simultaneous theta (6.6 ± 0.1 Hz) and gamma (36.6 ± 0.4 Hz) oscillations in rodent primary motor cortex (M1). Each oscillation showed greatest power in layer V...
April 8, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28385876/concurrent-tacs-fmri-reveals-causal-influence-of-power-synchronized-neural-activity-on-resting-state-fmri-connectivity
#10
Marc Bächinger, Valerio Zerbi, Marius Moisa, Rafael Polania, Quanying Liu, Dante Mantini, Christian Ruff, Nicole Wenderoth
Resting state fMRI (rs-fMRI) is commonly used to study the brain's intrinsic neural coupling, which reveals specific spatiotemporal patterns in the form of resting state networks (RSN). It has been hypothesized that slow rs-fMRI oscillations (<0.1 Hz) are driven by underlying electrophysiological rhythms that typically occur at much faster timescales (>5 Hz); however, causal evidence for this relationship is currently lacking. Here we measured rs-fMRI in humans while applying transcranial alternating current stimulation (tACS) to entrain brain rhythms in left and right sensorimotor cortices...
April 6, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28380064/a-neural-mass-model-of-cross-frequency-coupling
#11
Mojtaba Chehelcheraghi, Cees van Leeuwen, Erik Steur, Chie Nakatani
Electrophysiological signals of cortical activity show a range of possible frequency and amplitude modulations, both within and across regions, collectively known as cross-frequency coupling. To investigate whether these modulations could be considered as manifestations of the same underlying mechanism, we developed a neural mass model. The model provides five out of the theoretically proposed six different coupling types. Within model components, slow and fast activity engage in phase-frequency coupling in conditions of low ambient noise level and with high noise level engage in phase-amplitude coupling...
2017: PloS One
https://www.readbyqxmd.com/read/28372134/vortex-sound-radiation-in-a-flow-duct-with-a-dipole-source-and-a-flexible-wall-of-finite-length
#12
Y K Chiang, Y S Choy, S K Tang
The noise attenuation of fan-ducted noise at low blade-passage frequency remains a challenge. The present study investigates the noise reduction mechanism of a tensioned membrane housing device that directly controls the sound radiation from the doublet which is enclosed in an infinitely long duct with a point vortex. The time dependent sound radiation mechanism and the vibro-acoustics coupling mechanism of the systems are studied by adopting the potential theory and matched asymptotic expansion technique. The silencing performance of such a passive approach depends on the amplitude and phase of the sound field created by the doublet and the acoustic pressure induced by the membrane oscillation in order to achieve sound cancellation...
March 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28364760/chimera-states-and-the-interplay-between-initial-conditions-and-non-local-coupling
#13
Peter Kalle, Jakub Sawicki, Anna Zakharova, Eckehard Schöll
Chimera states are complex spatio-temporal patterns that consist of coexisting domains of coherent and incoherent dynamics. We study chimera states in a network of non-locally coupled Stuart-Landau oscillators. We investigate the impact of initial conditions in combination with non-local coupling. Based on an analytical argument, we show how the coupling phase and the coupling strength are linked to the occurrence of chimera states, flipped profiles of the mean phase velocity, and the transition from a phase- to an amplitude-mediated chimera state...
March 2017: Chaos
https://www.readbyqxmd.com/read/28364465/coordination-of-slow-waves-with-sleep-spindles-predicts-sleep-dependent-memory-consolidation-in-schizophrenia
#14
Charmaine Demanuele, Ullrich Bartsch, Bengi Baran, Sheraz Khan, Mark G Vangel, Roy Cox, Matti Hämäläinen, Matthew W Jones, Robert Stickgold, Dara S Manoach
Study Objectives: Schizophrenia patients have correlated deficits in sleep spindle density and sleep-dependent memory consolidation. In addition to spindle density, memory consolidation is thought to rely on the precise temporal coordination of spindles with slow waves (SWs). We investigated whether this coordination is intact in schizophrenia and its relation to motor procedural memory consolidation. Methods: Twenty-one chronic medicated schizophrenia patients and 17 demographically matched healthy controls underwent two nights of polysomnography, with training on the finger tapping motor sequence task (MST) on the second night and testing the following morning...
January 1, 2017: Sleep
https://www.readbyqxmd.com/read/28362728/dielectric-metasurfaces-solve-differential-and-integro-differential-equations
#15
Sajjad Abdollahramezani, Ata Chizari, Ali Eshaghian Dorche, Mohammad Vahid Jamali, Jawad A Salehi
Leveraging subwavelength resonant nanostructures, plasmonic metasurfaces have recently attracted much attention as a breakthrough concept for engineering optical waves both spatially and spectrally. However, inherent ohmic losses concomitant with low coupling efficiencies pose fundamental impediments over their practical applications. Not only can all-dielectric metasurfaces tackle such substantial drawbacks, but also their CMOS-compatible configurations support both Mie resonances that are invariant to the incident angle...
April 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28343333/use-of-phase-locking-value-in-sensorimotor-rhythm-based-brain-computer-interface-zero-phase-coupling-and-effects-of-spatial-filters
#16
Wenjuan Jian, Minyou Chen, Dennis J McFarland
Phase-locking value (PLV) is a potentially useful feature in sensorimotor rhythm-based brain-computer interface (BCI). However, volume conduction may cause spurious zero-phase coupling between two EEG signals and it is not clear whether PLV effects are independent of spectral amplitude. Volume conduction might be reduced by spatial filtering, but it is uncertain what impact this might have on PLV. Therefore, the goal of this study was to explore whether zero-phase PLV is meaningful and how it is affected by spatial filtering...
March 25, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28341856/autoassociative-memory-and-pattern-recognition-in-micromechanical-oscillator-network
#17
Ankit Kumar, Pritiraj Mohanty
Towards practical realization of brain-inspired computing in a scalable physical system, we investigate a network of coupled micromechanical oscillators. We numerically simulate this array of all-to-all coupled nonlinear oscillators in the presence of stochasticity and demonstrate its ability to synchronize and store information in the relative phase differences at synchronization. Sensitivity of behavior to coupling strength, frequency distribution, nonlinearity strength, and noise amplitude is investigated...
March 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28327465/anomalous-rashba-spin-orbit-interaction-in-electrically-controlled-topological-insulator-based-on-inn-gan-quantum-wells
#18
Sławomir P Łepkowski, Witold Bardyszewski
We study theoretically the topological phase transition and the Rashba spin-orbit interaction in electrically biased InN/GaN quantum wells. We show that that for properly chosen widths of quantum wells and barriers, one can effectively tune the system through the topological phase transition applying an external electric field perpendicular to the QW plane. We find that in InN/GaN quantum wells with the inverted band structure, when the conduction band s-type level is below the heavy hole and light hole p-type levels, the spin splitting of the subbands decreases with increasing the amplitude of the electric field in the quantum wells, which reveals the anomalous Rashba effect...
March 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28316753/a-resting-eeg-study-of-neocortical-hyperexcitability-and-altered-functional-connectivity-in-fragile-x-syndrome
#19
Jun Wang, Lauren E Ethridge, Matthew W Mosconi, Stormi P White, Devin K Binder, Ernest V Pedapati, Craig A Erickson, Matthew J Byerly, John A Sweeney
BACKGROUND: Cortical hyperexcitability due to abnormal fast-spiking inhibitory interneuron function has been documented in fmr1 KO mice, a mouse model of the fragile X syndrome which is the most common single gene cause of autism and intellectual disability. METHODS: We collected resting state dense-array electroencephalography data from 21 fragile X syndrome (FXS) patients and 21 age-matched healthy participants. RESULTS: FXS patients exhibited greater gamma frequency band power, which was correlated with social and sensory processing difficulties...
2017: Journal of Neurodevelopmental Disorders
https://www.readbyqxmd.com/read/28303088/commentary-phase-amplitude-coupling-at-the-organism-level-the-amplitude-of-spontaneous-alpha-rhythm-fluctuations-varies-with-the-phase-of-the-infra-slow-gastric-basal-rhythm
#20
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