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Cross-frequency coupling

F Schluck, G Lehmann, K H Spatschek
In a recent paper, M. R. Edwards, N. J. Fisch, and J. M. Mikhailova [Phys. Rev. Lett. 116, 015004 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.015004] reported that in electron-positron plasma stimulated Brillouin scattering is drastically enhanced, while stimulated Raman scattering is completely absent. However, when theory was compared to particle-in-cell (PIC) simulations, a discrepancy by at least a factor four appeared. Authors correctly argued that the disparity might be due to the fluid approximation of the low-frequency mode...
November 2017: Physical Review. E
Jintao Sheng, Yuedi Shen, Yanhua Qin, Lei Zhang, Binjia Jiang, Yaoyao Li, Luoyi Xu, Wei Chen, Jinhui Wang
Although imbalanced functional integration has been increasingly reported in major depressive disorder (MDD), there still lacks a general framework to characterize common characteristic and origin shared by the integrative disturbances. Here we examined spatial selectivity, temporal uniqueness, metabolic basis, and therapeutic response of altered functional connectivity (FC) in MDD by analyzing both cross-sectional and longitudinal multimodal functional magnetic resonance imaging data from 35 patients and 34 demographically matched healthy controls...
January 17, 2018: Human Brain Mapping
Ivani Brys, Pär Halje, Robson Scheffer-Teixeira, Mark Varney, Adrian Newman-Tancredi, Per Petersson
Recently, the biased and highly selective 5-HT1A agonists, NLX-112, F13714 and F15599, have been shown to alleviate dyskinesia in rodent and primate models of Parkinson's disease, while marginally interfering with antiparkinsonian effects of levodopa. To provide more detailed information on the processes underlying the alleviation of dyskinesia, we have here investigated changes in the spectral contents of local field potentials in cortico-basal ganglia-thalamic circuits following treatment with this novel group of 5-HT1A agonists or the prototypical agonist, 8-OH-DPAT...
January 12, 2018: Experimental Neurology
Takayuki Onojima, Takahiro Goto, Hiroaki Mizuhara, Toshio Aoyagi
Synchronization of neural oscillations as a mechanism of brain function is attracting increasing attention. Neural oscillation is a rhythmic neural activity that can be easily observed by noninvasive electroencephalography (EEG). Neural oscillations show the same frequency and cross-frequency synchronization for various cognitive and perceptual functions. However, it is unclear how this neural synchronization is achieved by a dynamical system. If neural oscillations are weakly coupled oscillators, the dynamics of neural synchronization can be described theoretically using a phase oscillator model...
January 2018: PLoS Computational Biology
B Dober, D T Becker, D A Bennett, S A Bryan, S M Duff, J D Gard, J P Hays-Wehle, G C Hilton, J Hubmayr, J A B Mates, C D Reintsema, L R Vale, J N Ullom
Key performance characteristics are demonstrated for the microwave SQUID multiplexer (µmux) coupled to transition edge sensor (TES) bolometers that have been optimized for cosmic microwave background (CMB) observations. In a 64-channel demonstration, we show that the µmux produces a white, input referred current noise level of [Formula: see text] at -77 dB microwave probe tone power, which is well below expected fundamental detector and photon noise sources for a ground-based CMB-optimized bolometer. Operated with negligible photon loading, we measure [Formula: see text] in the TES-coupled channels biased at 65% of the sensor normal resistance...
December 2017: Applied Physics Letters
Gabriel Amador de Lara, Ivan Alekseichuk, Zsolt Turi, Albert Lehr, Andrea Antal, Walter Paulus
BACKGROUND: Phase-amplitude cross-frequency coupling (PAC) is characterized by the modulation of the power of a fast brain oscillation (e.g., gamma) by the phase of a slow rhythm (e.g., theta). PAC in different sub- and neocortical regions is known to underlie effective neural communication and correlates with successful long-term memory formation. OBJECTIVE/HYPOTHESIS: The present work aims to extend earlier observational data, by probing the functional role of theta-gamma PAC in the left temporal cortex in humans during verbal long-term memory encoding...
December 25, 2017: Brain Stimulation
Erik Andris, Rafael Navrátil, Juraj Jašík, Gerard Sabenya, Miquel Costas, Martin Srnec, Jana Roithová
We report for the first time infrared spectra of three non-heme pseudo-octahedral iron(V) nitride complexes with assigned Fe-N stretching vibrations. The intensities of the Fe-N bands in two of the complexes are extremely weak. Their detection was enabled by the high resolution and sensitivity of the experiments performed at 3 K for isolated complexes in the gas phase. Multireference CASPT2 calculations revealed that the Fe-N bond in the ground doublet state is influenced by two low-lying excited doublet states...
January 3, 2018: Chemistry: a European Journal
Gary O'Donovan, Emmanuel Stamatakis, Mark Hamer
The objective of this cross-sectional study was to clarify the association between alcohol and obesity using data from 106 182 adults in England and Scotland (46·7 % male; mean 46·9 (sd 16·9) years). Trained interviewers asked participants about alcohol intake. Obesity was defined as BMI≥30 kg/m2. Potential confounders included age, sex, smoking, physical activity, longstanding illness, psychological distress and socioeconomic status. Compared with those who drank at least five times a week, obesity risk was 1·21 (95 % CI 1·15, 1·27) in those who drank one to four times a week, 1·53 (95 % CI 1·43, 1·62) in those who drank one to two times a month, 1·61 (95 % CI 1·52, 1·71) in those who drank less than once every couple of months, 1·34 (95 % CI 1·23, 1·47) in those who were former drinkers, and 1·03 (95 % CI 0·95, 1·11) in those who were never drinkers...
January 8, 2018: British Journal of Nutrition
Erwann Guenin, Farah Benyettou Benyettou, Hassan Traboulsi, Laurence Motte Motte, Javed Mazer, Renu Pasricha Pasricha, John-Carl Olsen Olsen, Ali Trabolsi
Cucurbit[7]uril modified iron oxide nanoparticles (CB[7]NPs) were loaded with palladium to form nano-catalysts (Pd@CB[7]NPs) that, with microwave heating, catalysed Suzuki-Miyaura, Sonogashira, and Mizoroki-Heck cross coupling reactions. All reactions were run in environmentally benign 1/1 ethanol/water solvent under convenient aerobic conditions. In a preliminary screening, all conversions and yields were uniformly high with turn over frequencies (TOF) ranging from 64 to 7360 h-1. The nano-catalysts could be recovered with a magnet and reused several times (6 times for Suzuki Miayura reaction) without loss of activity...
January 3, 2018: Chemistry: a European Journal
Daojing Guo, Qiming Hu, Da Li, Chengshuo Shen, Nengchao Wang, Zhuo Huang, Mingxiang Huang, Yonghua Ding, Guo Xu, Qingquan Yu, Yuejin Tang, Ge Zhuang
The magnetic diagnostic of Mirnov probe arrays has been upgraded on the J-TEXT tokamak to measure the magnetohydrodynamic instabilities with higher spatial resolution and better amplitude-frequency characteristics. The upgraded Mirnov probe array contains one poloidal array with 48 probe modules and two toroidal arrays with 25 probe modules. Each probe module contains two probes which measure both the poloidal and the radial magnetic fields (Bp and Br). To ensure that the Mirnov probe possess better amplitude-frequency characteristics, a novel kind of Mirnov probe made of low temperature co-fired ceramics is utilized...
December 2017: Review of Scientific Instruments
Makoto Tamura, Timothy J Spellman, Andrew M Rosen, Joseph A Gogos, Joshua A Gordon
Cross-frequency coupling supports the organization of brain rhythms and is present during a range of cognitive functions. However, little is known about whether and how long-range cross-frequency coupling across distant brain regions subserves working memory. Here we report that theta-slow gamma coupling between the hippocampus and medial prefrontal cortex (mPFC) is augmented in a genetic mouse model of cognitive dysfunction. This increased cross-frequency coupling is observed specifically when the mice successfully perform a spatial working memory task...
December 19, 2017: Nature Communications
Randolph F Helfrich, Bryce A Mander, William J Jagust, Robert T Knight, Matthew P Walker
The coupled interaction between slow-wave oscillations and sleep spindles during non-rapid-eye-movement (NREM) sleep has been proposed to support memory consolidation. However, little evidence in humans supports this theory. Moreover, whether such dynamic coupling is impaired as a consequence of brain aging in later life, contributing to cognitive and memory decline, is unknown. Combining electroencephalography (EEG), structural MRI, and sleep-dependent memory assessment, we addressed these questions in cognitively normal young and older adults...
December 12, 2017: Neuron
Floriana Pichiorri, Manuela Petti, Stefano Caschera, Laura Astolfi, Febo Cincotti, Donatella Mattia
Brain connectivity has been employed to investigate on post-stroke recovery mechanisms and assess the effect of specific rehabilitation interventions. Changes in interhemispheric coupling after stroke have been related to the extent of damage in the corticospinal tract (CST) and thus, to motor impairment. In this study we aim at defining an index of interhemispheric connectivity derived from electroencephalography (EEG), correlated with CST integrity and clinical impairment. Thirty sub-acute stroke patients underwent clinical and neurophysiological evaluation: CST integrity was assessed by Transcranial Magnetic Stimulation and high-density EEG was recorded at rest...
December 15, 2017: European Journal of Neuroscience
Giovanni Mento, Duncan E Astle, Gaia Scerif
Temporal orienting of attention operates by biasing the allocation of cognitive and motor resources in specific moments in time, resulting in the improved processing of information from expected compared with unexpected targets. Recent findings have shown that temporal orienting operates relatively early across development, suggesting that this attentional mechanism plays a core role for human cognition. However, the exact neurophysiological mechanisms allowing children to attune their attention over time are not well understood...
December 15, 2017: Journal of Cognitive Neuroscience
Nathan Dostart, Yangyang Liu, Miloš A Popović
A numerical method of solving for the elastic wave eigenmodes in acoustic waveguides of arbitrary cross-section is presented. Operating under the assumptions of linear, isotropic materials, it utilizes a finite-difference method on a staggered grid to solve for the acoustic eigenmodes (field and frequency) of the vector-field elastic wave equation with a given propagation constant. Free, fixed, symmetry, and anti-symmetry boundary conditions are implemented, enabling efficient simulation of acoustic structures with geometrical symmetries and terminations...
December 13, 2017: Scientific Reports
Kong Ooi Tan, Vipin Agarwal, Nils-Alexander Lakomek, Susanne Penzel, Beat H Meier, Matthias Ernst
Through-bond J-coupling based experiments in solid-state NMR spectroscopy are challenging because the J couplings are typically much smaller than the dipolar couplings. This often leads to a lower transfer efficiency compared to dipolar-coupling based sequences. One of the reasons for the low transfer efficiency are the second-order cross terms involving the strong heteronuclear dipolar couplings leading to fast magnetization decay. Here, we show that by employing a symmetry-based C9 sequence, which was carefully selected to suppress second-order terms, efficient polarization transfers of up to 80% can be achieved without decoupling on fully protonated two-spin model systems at a MAS frequency of 55...
December 5, 2017: Solid State Nuclear Magnetic Resonance
Tom Dupré la Tour, Lucille Tallot, Laetitia Grabot, Valérie Doyère, Virginie van Wassenhove, Yves Grenier, Alexandre Gramfort
We address the issue of reliably detecting and quantifying cross-frequency coupling (CFC) in neural time series. Based on non-linear auto-regressive models, the proposed method provides a generative and parametric model of the time-varying spectral content of the signals. As this method models the entire spectrum simultaneously, it avoids the pitfalls related to incorrect filtering or the use of the Hilbert transform on wide-band signals. As the model is probabilistic, it also provides a score of the model "goodness of fit" via the likelihood, enabling easy and legitimate model selection and parameter comparison; this data-driven feature is unique to our model-based approach...
December 11, 2017: PLoS Computational Biology
Laura Gagliano, Elie Bou Assi, Dang K Nguyen, Sandy Rihana, Mohamad Sawan
Seizure forecasting would improve the quality of life of patients with refractory epilepsy. Although early findings were optimistic, no single feature has been found capable of individually characterizing brain dynamics during transition to seizure. Cross-frequency phase amplitude coupling has been recently proposed as a precursor of seizure activity. This work evaluates the existence of a statistically significant difference in mean phase amplitude coupling distribution between the preictal and interictal states of seizures in dogs with bilaterally implanted intracranial electrodes...
November 26, 2017: Epilepsy Research
Shiqian Ding, Gleb Maslennikov, Roland Hablützel, Dzmitry Matsukevich
State measurement of a quantum harmonic oscillator is essential in quantum optics and quantum information processing. In a system of trapped ions, we experimentally demonstrate the projective measurement of the state of the ions' motional mode via an effective cross-Kerr coupling to another motional mode. This coupling is induced by the intrinsic nonlinearity of the Coulomb interaction between the ions. We spectroscopically resolve the frequency shift of the motional sideband of the first mode due to the presence of single phonons in the second mode and use it to reconstruct the phonon number distribution of the second mode...
November 10, 2017: Physical Review Letters
John McCamley, William Denton, Elizabeth Lyden, Jennifer M Yentes
The aim of this investigation was to compare and contrast the use of cross sample entropy (xSE) and cross recurrence quantification analysis (cRQA) measures for the assessment of coupling of rhythmical patterns. Measures were assessed using simulated signals with regular, chaotic, and random fluctuations in frequency, amplitude, and a combination of both. Biological data were studied as models of normal and abnormal locomotor-respiratory coupling. Nine signal types were generated for seven frequency ratios...
2017: Computational and Mathematical Methods in Medicine
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