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Phase amplitude coupling

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https://www.readbyqxmd.com/read/28101528/discriminating-valid-from-spurious-indices-of-phase-amplitude-coupling
#1
Ole Jensen, Eelke Spaak, Hyojin Park
Recently there has been a strong interest in cross-frequency coupling, the interaction between neuronal oscillations in different frequency bands. In particular, measures quantifying the coupling between the phase of slow oscillations and the amplitude of fast oscillations have been applied to a wide range of data recorded from animals and humans. Some of the measures applied to detect phase-amplitude coupling have been criticized for being sensitive to nonsinusoidal properties of the oscillations and thus spuriously indicate the presence of coupling...
November 2016: ENeuro
https://www.readbyqxmd.com/read/28100654/dissociation-between-sustained-single-neuron-spiking-%C3%AE-rhythmicity-and-transient-%C3%AE-lfp-oscillations-in-primate-motor-cortex
#2
Michael Everett Rule, Carlos E Vargas-Irwin, John P Donoghue, Wilson Truccolo
Determining the relationship between single-neuron spiking and transient (~20 Hz) beta local field potential (β-LFP) oscillations is an important step for understanding the role of these oscillations in motor cortex. We show that while motor cortex firing rates and beta spiking rhythmicity remain sustained during steady-state movement preparation periods, β-LFP oscillations emerge, in contrast, as short transient events. Single-neuron mean firing rates within and outside transient β-LFP events showed no differences, and no consistent correlation was found between the beta oscillations' amplitude and firing rates, as was the case for movement and visual-cue related β-LFP suppression...
January 18, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28093359/fmri-characterisation-of-widespread-brain-networks-relevant-for-behavioural-variability-in-fine-hand-motor-control-with-and-without-visual-feedback
#3
Stephen D Mayhew, Camillo Porcaro, Franca Tecchio, Andrew P Bagshaw
A bilateral visuo-parietal-motor network is responsible for fine control of hand movements. However, the sub-regions which are devoted to maintenance of contraction stability and how these processes fluctuate with trial-quality of task execution and in the presence/absence of visual feedback remains unclear. We addressed this by integrating behavioural and fMRI measurements during right-hand isometric compression of a compliant rubber bulb, at 10% and 30% of maximum voluntary contraction, both with and without visual feedback of the applied force...
January 13, 2017: NeuroImage
https://www.readbyqxmd.com/read/28077711/phase-amplitude-coupling-and-long-range-phase-synchronization-reveal-frontotemporal-interactions-during-visual-working-memory
#4
Jonathan Daume, Thomas Gruber, Andreas K Engel, Uwe Friese
: It has been suggested that cross-frequency phase-amplitude coupling (PAC), particularly in temporal brain structures, serves as a neural mechanism for coordinated working memory storage. In this magnetoencephalography study, we show that during visual working memory maintenance, temporal cortex regions, which exhibit enhanced PAC, interact with prefrontal cortex via enhanced low-frequency phase synchronization. Healthy human participants were engaged in a visual delayed match-to-sample task with pictures of natural objects...
January 11, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28065849/dual-origins-of-measured-phase-amplitude-coupling-reveal-distinct-neural-mechanisms-underlying-episodic-memory-in-the-human-cortex
#5
Alex P Vaz, Robert B Yaffe, John H Wittig, Sara K Inati, Kareem A Zaghloul
Phase-amplitude coupling (PAC) is hypothesized to coordinate neural activity, but its role in successful memory formation in the human cortex is unknown. Measures of PAC are difficult to interpret, however. Both increases and decreases in PAC have been linked to memory encoding, and PAC may arise due to different neural mechanisms. Here, we use a waveform analysis to examine PAC in the human cortex as participants with intracranial electrodes performed a paired associates memory task. We found that successful memory formation exhibited significant decreases in left temporal lobe and prefrontal cortical PAC, and these two regions exhibited changes in PAC within different frequency bands...
January 6, 2017: NeuroImage
https://www.readbyqxmd.com/read/28059372/contribution-of-off-resonant-states-to-the-phase-noise-of-quantum-dot-lasers
#6
Cheng Wang, Jun-Ping Zhuang, Frédéric Grillot, Sze-Chun Chan
The phase noise of quantum dot lasers is investigated theoretically by coupling the Langevin noise sources into the rate equations. The off-resonant populations in the excited state and in the carrier reservoir contribute to the phase noise of ground-state emission lasers through the phase-amplitude coupling effect. This effect arises from the optical-noise induced carrier fluctuations in the off-resonant states. In addition, the phase noise has low sensitivity to the carrier scattering rates.
December 26, 2016: Optics Express
https://www.readbyqxmd.com/read/28054662/tunable-metasurfaces-via-subwavelength-phase-shifters-with-uniform-amplitude
#7
Shane Colburn, Alan Zhan, Arka Majumdar
Metasurfaces with tunable spatial phase functions could benefit numerous applications. Currently, most approaches to tuning rely on mechanical stretching which cannot control phase locally, or by modulating the refractive index to exploit rapid phase changes with the drawback of also modulating amplitude. Here, we propose a method to realize phase modulation at subwavelength length scales while maintaining unity amplitude. Our device is inspired by an asymmetric Fabry-Perot resonator, with pixels comprising a scattering nanopost on top of a distributed Bragg reflector, capable of providing a nearly 2π nonlinear phase shift with less than 2% refractive index modulation...
January 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28035088/nematic-films-at-chemically-structured-surfaces
#8
N M Silvestre, M M Telo da Gama, M Tasinkevych
We investigate theoretically the morphology of a thin nematic film adsorbed at flat substrate patterned by stripes with alternating aligning properties, normal and tangential respectively. We construct a simple 'exactly-solvable' effective interfacial model where the liquid crystal distortions are accounted for via an effective interface potential. We find that chemically patterned substrates can strongly deform the nematic-air interface. The amplitude of this substrate-induced undulations increases with decreasing average film thickness and with increasing surface pattern pitch...
February 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28012561/peripheral-apelin-13-administration-inhibits-gastrointestinal-motor-functions-in-rats-the-role-of-cholecystokinin-through-cck1-receptor-mediated-pathway
#9
Mehmet Bülbül, Osman Sinen, İlknur Birsen, V Nimet İzgüt-Uysal
Apelin is the endogenous ligand of the G protein-coupled receptor APJ. The APJ receptor is widely expressed in gastrointestinal (GI) tissues including stomach and small intestine. Apelin administration was shown to induce the release of cholecystokinin (CCK) which is a well-known alimentary hormone with its inhibitory actions on GI motor functions through CCK1 receptors on vagal afferent fibers. We investigated whether; (i) peripherally injected apelin-13 alters GI motor functions, (ii) apelin-induced changes are mediated by APJ receptor or CCK1 receptor and (iii) vagal afferents are involved in inhibitory effects of apelin...
December 16, 2016: Neuropeptides
https://www.readbyqxmd.com/read/27993014/modulation-of-elasticity-and-interactions-in-charged-lipid-multibilayers-monovalent-salt-solutions
#10
Bing-Sui Lu, Santosh Prasad Gupta, Michal Belička, Rudolf Podgornik, Georg Pabst
We have studied the electrostatic screening effect of NaCl solutions on the interactions between anionic lipid bilayers in the fluid lamellar phase using a Poisson-Boltzmann-based mean-field approach with constant charge and constant potential limiting charge regulation boundary conditions. The full DLVO potential, including the electrostatic, hydration and van der Waals interactions, was coupled to thermal bending fluctuations of the membranes via a variational Gaussian Ansatz. This allowed us to analyze the coupling between the osmotic pressure and the fluctuation amplitudes and compare them both simultaneously with their measured dependence on the bilayer separation, determined by the small-angle X-ray scattering experiments...
December 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/27979981/effects-of-different-stresses-on-cardiac-autonomic-control-and-cardiovascular-coupling
#11
Lin Xie, Binbin Liu, Xiaoni Wang, Mengqi Mei, Mengjun Li, Xiaolin Yu, Jianbao Zhang
The objective of this study was to investigate the impacts of different stresses on time varying autonomic reactivity and cardiovascular coupling. In total, 25 male subjects were recruited. RR intervals (RRI), systolic and diastolic blood pressure (SBP, DBP), stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) values were collected during rest, mental arithmetic task (MAT) and cold pressor test (CPT). Baroreflex sensitivity (BRS) was derived using the transfer function method. Continuous wavelet transform of RRI was used to describe the time variant patterns of autonomic neural activities...
December 15, 2016: Journal of Applied Physiology
https://www.readbyqxmd.com/read/27941990/non-sinusoidal-activity-can-produce-cross-frequency-coupling-in-cortical-signals-in-the-absence-of-functional-interaction-between-neural-sources
#12
Edden M Gerber, Boaz Sadeh, Andrew Ward, Robert T Knight, Leon Y Deouell
The analysis of cross-frequency coupling (CFC) has become popular in studies involving intracranial and scalp EEG recordings in humans. It has been argued that some cases where CFC is mathematically present may not reflect an interaction of two distinct yet functionally coupled neural sources with different frequencies. Here we provide two empirical examples from intracranial recordings where CFC can be shown to be driven by the shape of a periodic waveform rather than by a functional interaction between distinct sources...
2016: PloS One
https://www.readbyqxmd.com/read/27936784/dynamic-reflection-phase-and-polarization-control-in-metasurfaces
#13
Junghyun Park, Ju-Hyung Kang, Soo Jin Kim, Xiaoge Liu, Mark L Brongersma
Optical metasurfaces are two-dimensional optical elements composed of dense arrays of subwavelength optical antennas and afford on-demand manipulation of the basic properties of light waves. Following the pioneering works on active metasurfaces capable of modulating wave amplitude, there is now a growing interest to dynamically control other fundamental properties of light. Here, we present metasurfaces that facilitate electrical tuning of the reflection phase and polarization properties. To realize these devices, we leverage the properties of actively controlled plasmonic antennas and fundamental insights provided by coupled mode theory...
December 12, 2016: Nano Letters
https://www.readbyqxmd.com/read/27932971/evaluation-of-phase-amplitude-coupling-in-resting-state-magnetoencephalographic-signals-effect-of-surrogates-and-evaluation-approach
#14
Bakul Gohel, Sanghyun Lim, Min-Young Kim, Kyung-Min An, Ji-Eun Kim, Hyukchan Kwon, Kiwoong Kim
Phase-amplitude coupling (PAC) plays an important role in neural communication and computation. Interestingly, recent studies have indicated the presence of ubiquitous PAC phenomenon even during the resting state. Despite the importance of PAC phenomenon, estimation of significant physiological PAC is challenging because of the lack of appropriate surrogate measures to control false positives caused by non-physiological PAC. Therefore, in the present study, we evaluated PAC phenomenon during resting-state magnetoencephalography (MEG) signal and considered various surrogate measures and computational approaches widely used in the literature in addition to proposing new ones...
2016: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/27925581/on-cross-frequency-phase-phase-coupling-between-theta-and-gamma-oscillations-in-the-hippocampus
#15
Robson Scheffer-Teixeira, Adriano Bl Tort
Phase-amplitude coupling between theta and multiple gamma sub-bands is a hallmark of hippocampal activity and believed to take part in information routing. More recently, theta and gamma oscillations were also reported to exhibit phase-phase coupling, or n:m phase-locking, suggesting an important mechanism of neuronal coding that has long received theoretical support. However, by analyzing simulated and actual LFPs, here we question the existence of theta-gamma phase-phase coupling in the rat hippocampus. We show that the quasi-linear phase shifts introduced by filtering lead to spurious coupling levels in both white noise and hippocampal LFPs, which highly depend on epoch length, and that significant coupling may be falsely detected when employing improper surrogate methods...
December 7, 2016: ELife
https://www.readbyqxmd.com/read/27915117/from-intentions-to-actions-neural-oscillations-encode-motor-processes-through-phase-amplitude-and-phase-amplitude-coupling
#16
Etienne Combrisson, Marcela Perrone-Bertolotti, Juan Lp Soto, Golnoush Alamian, Philippe Kahane, Jean-Philippe Lachaux, Aymeric Guillot, Karim Jerbi
Goal-directed motor behavior is associated with changes in patterns of rhythmic neuronal activity across widely distributed brain areas. In particular, movement initiation and execution are mediated by patterns of synchronization and desynchronization that occur concurrently across distinct frequency bands and across multiple motor cortical areas. To date, motor-related local oscillatory modulations have been predominantly examined by quantifying increases or suppressions in spectral power. However, beyond signal power, spectral properties such as phase and phase-amplitude coupling (PAC) have also been shown to carry information with regards to the oscillatory dynamics underlying motor processes...
November 30, 2016: NeuroImage
https://www.readbyqxmd.com/read/27910344/icrf-wave-field-measurements-in-the-presence-of-scrape-off-layer-turbulence-on-the-asdex-upgrade-tokamak-invited
#17
R Ochoukov, V Bobkov, H Faugel, H Fünfgelder, J Jacquot, J-M Noterdaeme, G Suárez López
A new array of B-dot probes was installed on ASDEX Upgrade. The purpose of the new diagnostic is to study Ion Cyclotron Range-off Frequencies (ICRF) wave field distributions in the evanescent scrape-off layer (SOL) plasma region on the low field side of ASDEX Upgrade. The vacuum measurements (no gas, BT = 0 T) reveal ICRF wave field measurements consistent with the profiles expected from the newly installed 3-strap ICRF antennas outside the antenna box: the shape of the toroidal distribution of both the amplitude and the phase is the same for the case of only the central straps being active, as for the case of only the side straps being active...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27908013/oscillation-quenching-in-third-order-phase-locked-loop-coupled-by-mean-field-diffusive-coupling
#18
S Chakraborty, M Dandapathak, B C Sarkar
We explored analytically the oscillation quenching phenomena (amplitude death and parameter dependent inhomogeneous steady state) in a coupled third order phase locked loop (PLL) both in periodic and chaotic mode. The phase locked loops were coupled through mean field diffusive coupling. The lower and upper limits of the quenched state were identified in the parameter space of the coupled PLL using the Routh-Hurwitz technique. We further observed that the ability of convergence to the quenched state of coupled PLLs depends on the design parameters...
November 2016: Chaos
https://www.readbyqxmd.com/read/27903706/phase-amplitude-coupling-and-long-range-phase-synchronization-reveal-frontotemporal-interactions-during-visual-working-memory
#19
Jonathan Daume, Thomas Gruber, Andreas K Engel, Uwe Friese
: It has been suggested that cross-frequency phase-amplitude coupling (PAC) particularly in temporal brain structures serves as a neural mechanism for coordinated working memory storage. In this magnetoencephalography study, we show that during visual working memory maintenance, temporal cortex regions, which exhibit enhanced PAC, interact with prefrontal cortex via enhanced low-frequency phase synchronization. Healthy human participants were engaged in a visual delayed-matching-to-sample task with pictures of natural objects...
November 30, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27897244/neural-oscillations-in-the-temporal-pole-for-a-temporally-congruent-audio-visual-speech-detection-task
#20
Takefumi Ohki, Atsuko Gunji, Yuichi Takei, Hidetoshi Takahashi, Yuu Kaneko, Yosuke Kita, Naruhito Hironaga, Shozo Tobimatsu, Yoko Kamio, Takashi Hanakawa, Masumi Inagaki, Kazuo Hiraki
Though recent studies have elucidated the earliest mechanisms of processing in multisensory integration, our understanding of how multisensory integration of more sustained and complicated stimuli is implemented in higher-level association cortices is lacking. In this study, we used magnetoencephalography (MEG) to determine how neural oscillations alter local and global connectivity during multisensory integration processing. We acquired MEG data from 15 healthy volunteers performing an audio-visual speech matching task...
November 29, 2016: Scientific Reports
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