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Evidence for age-related changes in sensorimotor neuromagnetic responses during cued button pressing in a large open-access dataset

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NEUROIMAGE 2019年 193卷 25-34页

作者： Bardouille, Timothy Bailey, Lyam Dalhousie Univ Dept Phys & Atmospher Sci Halifax NS Canada Dalhousie Univ Dept Psychol & Neurosci Halifax NS Canada Univ Cambridge Cambridge Ctr Ageing & Neurosci Cambridge England

Mu, beta, and gamma rhythms increase and decrease in amplitude during movement. This event-related synchronization (ERS) and desynchronization (ERD) can be readily recorded non-invasively using magneto-and electro-encephalography (M/EEG). In addition, event-related potentials and fields (i. e., evoked responses) can be elucidated during movement. There is some evidence that the frequency, amplitude and latency of the movement-related ERS/ERD changes with ageing, however the evidence surrounding this topic comes mainly from studies in sample sizes on the order of tens of participants. The objective of this study was to examine a large open-access MEG dataset for age-related changes in movement-related ERS/ERD and evoked responses. MEG data acquired at the Cambridge Centre for Ageing and Neuroscience during cued button pressing was used from 567 participants between the ages of 18 and 88 years. The characteristics movement-related ERD/ERS and evoked responses were calculated for each individual participant. Based on linear regression analysis, significant relationships were found between participant age and some response characteristics, although the predictive value of these relationships was low. Specifically, we conclude that peak beta rebound frequency and amplitude decreased with age, peak beta suppression amplitude increased with age, movement-related gamma burst amplitude decreased with age, and peak motor-evoked response amplitude increased with age. Given our current understanding of the underlying mechanisms of these responses, our findings suggest the existence of age-related changes in the neurophysiology of thalamocortical loops and local circuitry in the primary somatosensory and motor cortices.

关键词： SOMATOSENSORY cortex MOTOR cortex REGRESSION analysis linear statistical models BUTTONS

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THE NULL-GEODESIC FLOW NEAR HORIZONS

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TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY 2019年第7期371卷 4769-4791页

作者： Gannot, Oran Northwestern Univ Dept Math Lunt Hall Evanston IL 60208 USA

This note describes the behavior of null-geodesics near nondegenerate Killing horizons in language amenable to the application of a general framework, due to Vasy and Hintz, for the analysis of both linear and nonlinear wave equations. Throughout, the viewpoint of Melrose's b-geometry on a suitable compactification of spacetime at future infinity is adopted.

关键词： HORIZON linear statistical models INFINITY (Mathematics) NONlinear wave equations

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Responses to the comment on the paper ''Effect of impurities on the onset and the growth of gravitational instabilities in a geological CO2 storage process: linear and nonlinear analyses" by MC Kim and KH Song

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CHEMICAL ENGINEERING SCIENCE 2019年 193卷 184-187页

作者： Kim, Min Chan Song, Kwang Ho Jeju Natl Univ Dept Chem Engn Jeju 63243 South Korea Korea Univ Dept Chem & Biol Engn Seoul 028411 South Korea

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Inferring hidden structure in multilayered neural circuits

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PLOS COMPUTATIONAL BIOLOGY 2018年第8期14卷 e1006291-e1006291页

作者： Maheswaranathan, Niru Kastner, David B. Baccus, Stephen A. Ganguli, Surya Stanford Univ Neurosci Grad Program Stanford CA 94305 USA Stanford Univ Dept Neurobiol Stanford CA 94305 USA Stanford Univ Dept Appl Phys Stanford CA 94305 USA Google Brain Mountain View CA USA UCSF Dept Psychiat San Francisco CA USA

A central challenge in sensory neuroscience involves understanding how neural circuits shape computations across cascaded cell layers. Here we attempt to reconstruct the response properties of experimentally unobserved neurons in the interior of a multilayered neural circuit, using cascaded linear-nonlinear (LN-LN) models. We combine non-smooth regularization with proximal consensus algorithms to overcome difficulties in fitting such models that arise from the high dimensionality of their parameter space. We apply this framework to retinal ganglion cell processing, learning LN-LN models of retinal circuitry consisting of thousands of parameters, using 40 minutes of responses to white noise. Our models demonstrate a 53% improvement in predicting ganglion cell spikes over classical linear-nonlinear (LN) models. Internal nonlinear subunits of the model match properties of retinal bipolar cells in both receptive field structure and number. Subunits have consistently high thresholds, supressing all but a small fraction of inputs, leading to sparse activity patterns in which only one subunit drives ganglion cell spiking at any time. From the model's parameters, we predict that the removal of visual redundancies through stimulus decorrelation across space, a central tenet of efficient coding theory, originates primarily from bipolar cell synapses. Furthermore, the composite nonlinear computation performed by retinal circuitry corresponds to a boolean OR function applied to bipolar cell feature detectors. Our methods are statistically and computationally efficient, enabling us to rapidly learn hierarchical non-linear models as well as efficiently compute widely used descriptive statistics such as the spike triggered average (STA) and covariance (STC) for high dimensional stimuli. This general computational framework may aid in extracting principles of nonlinear hierarchical sensory processing across diverse modalities from limited data.

关键词： NEUROSCIENCES NEURAL circuitry CASCADES (Fluid dynamics) linear statistical models NONlinear analysis

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Cornell Potential: A Neural Network Approach

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ADVANCES IN HIGH ENERGY PHYSICS 2019年第1期2019卷 1-9页

作者： Mutuk, Halil Ondokuz Mayis Univ Fac Arts & Sci Phys Dept TR-55200 Samsun Turkey

We solved Schrodinger equation with Cornell potential (Coulomb-plus-linear potential) by using neural network approach. Four different cases of Cornell potential for different potential parameters were used without a physical relevance. Besides that charmonium, bottomonium and bottom-charmed spin-averaged spectra were also calculated. Obtained results are in good agreement with the reference studies and available experimental data.

关键词： NEURAL circuitry SPECTRUM analysis COULOMB potential CHARMONIUM linear statistical models

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SUBSPACE DESIGNS BASED ON ALGEBRAIC FUNCTION FIELDS

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TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY 2018年第12期370卷 8757-8775页

作者： Guruswami, Venkatesan Xing, Chaoping Yuan, Chen Carnegie Mellon Univ Dept Comp Sci Pittsburgh PA 15213 USA Nanyang Technol Univ Sch Phys & Math Sci Singapore 637616 Singapore CWI Sci Pk 123 NL-1098 XG Amsterdam Netherlands

Subspace designs are a (large) collection of high-dimensional subspaces {H-i- of F-q(m) such that for any low-dimensional subspace W, only a small number of subspaces from the collection have non-trivial intersection with W;more precisely, the sum of dimensions of W boolean AND H-i is at most some parameter L. The notion was put forth by Guruswami and Xing (STOC'13) with applications to list decoding variants of Reed-Solomon and algebraic-geometric codes and later also used for explicit rank-metric codes with optimal list decoding radius. Guruswami and Kopparty (FOCS'13, Combinatorica '16) gave an explicit construction of subspace designs with near-optimal parameters. This construction was based on polynomials and has close connections to folded Reed Solomon codes and required large field size (specifically q >= m). Forbes and Guruswami (RANDOM'15) used this construction to give explicit constant degree "dimension expanders" over large fields and noted that subspace designs are a powerful tool in linear-algebraic pseudorandomness. Here, we construct subspace designs over any field, at the expense of a modest worsening of the bound L on total intersection dimension. Our approach is based on a (non-trivial) extension of the polynomial-based construction to algebraic function fields and instantiating the approach with cyclotomic function fields. Plugging in our new subspace designs in the construction of Forbes and Guruswami yields dimension expanders over F-n for any field F, with logarithmic degree and expansion guarantee for subspaces of dimension Omega(n/(log logn)).

关键词： SUBSPACES (Mathematics) ALGEBRAIC coding theory POLYNOMIALS linear statistical models MATHEMATICAL analysis

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Bifurcation, Chaos, and Pattern Formation for the Discrete Predator-Prey Reaction-Diffusion Model

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DISCRETE DYNAMICS IN NATURE AND SOCIETY 2019年第Pt.2期2019卷 1-9页

作者： Meng, Lili Han, Yutao Lu, Zhiyi Zhang, Guang Tianjin Univ Commerce Sch Sci Tianjin 300134 Peoples R China Univ Int Business & Econ Dept Econ Beijing 100029 Peoples R China

In this paper, a discrete predator-prey system with the periodic boundary conditions will be considered. First, we get the conditions for producing Turing instability of the discrete predator-prey system according to the linear stability analysis. Then, we show that the discretemodel has the flip bifurcation and Turing bifurcation under the critical parameter values. Finally, a series of numerical simulations are carried out in the Turing instability region of the discrete predator-prey model;some new Turing patterns such as striped, bar, and horizontal bar are observed.

关键词： PREDATION (Biology) linear systems DISCRETE systems linear statistical models COMPUTER simulation

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Detection of time reversibility in time series by ordinal patterns analysis

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CHAOS 2018年第12期28卷 123111-123111页

作者： Martinez, J. H. Herrera-Diestra, J. L. Chavez, M. Sorbonne Univ INSERM UM1127 Inst Cerveau & Moelle Epiniere F-75013 Paris France Univ Estadual Paulista ICTP South Amer Inst Fundamental Res IFT BR-01140070 Sao Paulo Brazil Hop La Pitie Salpetriere CNRS UMR7225 F-75013 Paris France

Time irreversibility is a common signature of nonlinear processes and a fundamental property of non-equilibrium systems driven by non-conservative forces. A time series is said to be reversible if its statistical properties are invariant regardless of the direction of time. Here, we propose the Time Reversibility from Ordinal Patterns method (TiROP) to assess time-reversibility from an observed finite time series. TiROP captures the information of scalar observations in time forward as well as its time-reversed counterpart by means of ordinal patterns. The method compares both underlying information contents by quantifying its (dis)-similarity via the Jensen-Shannon divergence. The statistic is contrasted with a population of divergences coming from a set of surrogates to unveil the temporal nature and its involved time scales. We tested TiROP in different synthetic and real, linear, and non-linear time series, juxtaposed with results from the classical Ramsey's time reversibility test. Our results depict a novel, fast-computation, and fully data-driven methodology to assess time-reversibility with no further assumptions over data. This approach adds new insights into the current non-linear analysis techniques and also could shed light on determining new physiological biomarkers of high reliability and computational efficiency. Published by AIP Publishing.

关键词： TIME series analysis NONlinear analysis linear statistical models DISTRIBUTION (Probability theory) DATA analysis

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Corrigendum to: "Covariance matrix formula for generalized linear models with unknown dispersion" by G. M. Cordeiro, L. P. Barroso, and D. A. Botter [Communications in Statistics-Theory and Methods (2006) 35(1), 113-120]

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Communications in Statistics: Theory and Methods 2017年第21期46卷 10702页

作者： Magalhães, Tiago M Botter, Denise A Sandoval, Mônica C Quantitative Research Itaú Asset Management São Paulo Brazil Department of Statistics University of São Paulo São Paulo Brazil

"Corrigendum to: “Covariance matrix formula for generalized linear models with unknown dispersion” by G. M. Cordeiro, L. P. Barroso, and D. A. Botter [Communications in Statistics—Theory and Methods (2006) 35(... 详细信息

关键词： COVARIANCE matrices linear statistical models

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Preface to the Special Issue on Advances on linear models and Inference: Computational Aspects

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COMMUNICATIONS IN STATISTICS-SIMULATION AND COMPUTATION 2014年第9期43卷 2045-2046页

作者： Filipiak, Katarzyna Puntanen, Simo [a] Editors of the Proceedings

Click to increase image sizeClick to decrease image size

关键词： SPECIAL issues of periodicals linear statistical models MATHEMATICAL statistics MATHEMATICAL models NUMERICAL analysis STATISTICS periodicals

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