der Statistical inference for autoregressive models under heteroscedasticity of unknown form By projecteuclid.org Published On :: Wed, 30 Oct 2019 22:03 EDT Ke Zhu. Source: The Annals of Statistics, Volume 47, Number 6, 3185--3215.Abstract: This paper provides an entire inference procedure for the autoregressive model under (conditional) heteroscedasticity of unknown form with a finite variance. We first establish the asymptotic normality of the weighted least absolute deviations estimator (LADE) for the model. Second, we develop the random weighting (RW) method to estimate its asymptotic covariance matrix, leading to the implementation of the Wald test. Third, we construct a portmanteau test for model checking, and use the RW method to obtain its critical values. As a special weighted LADE, the feasible adaptive LADE (ALADE) is proposed and proved to have the same efficiency as its infeasible counterpart. The importance of our entire methodology based on the feasible ALADE is illustrated by simulation results and the real data analysis on three U.S. economic data sets. Full Article
der Negative association, ordering and convergence of resampling methods By projecteuclid.org Published On :: Tue, 21 May 2019 04:00 EDT Mathieu Gerber, Nicolas Chopin, Nick Whiteley. Source: The Annals of Statistics, Volume 47, Number 4, 2236--2260.Abstract: We study convergence and convergence rates for resampling schemes. Our first main result is a general consistency theorem based on the notion of negative association, which is applied to establish the almost sure weak convergence of measures output from Kitagawa’s [ J. Comput. Graph. Statist. 5 (1996) 1–25] stratified resampling method. Carpenter, Ckiffird and Fearnhead’s [ IEE Proc. Radar Sonar Navig. 146 (1999) 2–7] systematic resampling method is similar in structure but can fail to converge depending on the order of the input samples. We introduce a new resampling algorithm based on a stochastic rounding technique of [In 42nd IEEE Symposium on Foundations of Computer Science ( Las Vegas , NV , 2001) (2001) 588–597 IEEE Computer Soc.], which shares some attractive properties of systematic resampling, but which exhibits negative association and, therefore, converges irrespective of the order of the input samples. We confirm a conjecture made by [ J. Comput. Graph. Statist. 5 (1996) 1–25] that ordering input samples by their states in $mathbb{R}$ yields a faster rate of convergence; we establish that when particles are ordered using the Hilbert curve in $mathbb{R}^{d}$, the variance of the resampling error is ${scriptstylemathcal{O}}(N^{-(1+1/d)})$ under mild conditions, where $N$ is the number of particles. We use these results to establish asymptotic properties of particle algorithms based on resampling schemes that differ from multinomial resampling. Full Article
der Correction: Sensitivity analysis for an unobserved moderator in RCT-to-target-population generalization of treatment effects By projecteuclid.org Published On :: Wed, 15 Apr 2020 22:05 EDT Trang Quynh Nguyen, Elizabeth A. Stuart. Source: The Annals of Applied Statistics, Volume 14, Number 1, 518--520. Full Article
der Estimating and forecasting the smoking-attributable mortality fraction for both genders jointly in over 60 countries By projecteuclid.org Published On :: Wed, 15 Apr 2020 22:05 EDT Yicheng Li, Adrian E. Raftery. Source: The Annals of Applied Statistics, Volume 14, Number 1, 381--408.Abstract: Smoking is one of the leading preventable threats to human health and a major risk factor for lung cancer, upper aerodigestive cancer and chronic obstructive pulmonary disease. Estimating and forecasting the smoking attributable fraction (SAF) of mortality can yield insights into smoking epidemics and also provide a basis for more accurate mortality and life expectancy projection. Peto et al. ( Lancet 339 (1992) 1268–1278) proposed a method to estimate the SAF using the lung cancer mortality rate as an indicator of exposure to smoking in the population of interest. Here, we use the same method to estimate the all-age SAF (ASAF) for both genders for over 60 countries. We document a strong and cross-nationally consistent pattern of the evolution of the SAF over time. We use this as the basis for a new Bayesian hierarchical model to project future male and female ASAF from over 60 countries simultaneously. This gives forecasts as well as predictive distributions that can be used to find uncertainty intervals for any quantity of interest. We assess the model using out-of-sample predictive validation and find that it provides good forecasts and well-calibrated forecast intervals, comparing favorably with other methods. Full Article
der Bayesian linear regression for multivariate responses under group sparsity By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Bo Ning, Seonghyun Jeong, Subhashis Ghosal. Source: Bernoulli, Volume 26, Number 3, 2353--2382.Abstract: We study frequentist properties of a Bayesian high-dimensional multivariate linear regression model with correlated responses. The predictors are separated into many groups and the group structure is pre-determined. Two features of the model are unique: (i) group sparsity is imposed on the predictors; (ii) the covariance matrix is unknown and its dimensions can also be high. We choose a product of independent spike-and-slab priors on the regression coefficients and a new prior on the covariance matrix based on its eigendecomposition. Each spike-and-slab prior is a mixture of a point mass at zero and a multivariate density involving the $ell_{2,1}$-norm. We first obtain the posterior contraction rate, the bounds on the effective dimension of the model with high posterior probabilities. We then show that the multivariate regression coefficients can be recovered under certain compatibility conditions. Finally, we quantify the uncertainty for the regression coefficients with frequentist validity through a Bernstein–von Mises type theorem. The result leads to selection consistency for the Bayesian method. We derive the posterior contraction rate using the general theory by constructing a suitable test from the first principle using moment bounds for certain likelihood ratios. This leads to posterior concentration around the truth with respect to the average Rényi divergence of order $1/2$. This technique of obtaining the required tests for posterior contraction rate could be useful in many other problems. Full Article
der A refined Cramér-type moderate deviation for sums of local statistics By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Xiao Fang, Li Luo, Qi-Man Shao. Source: Bernoulli, Volume 26, Number 3, 2319--2352.Abstract: We prove a refined Cramér-type moderate deviation result by taking into account of the skewness in normal approximation for sums of local statistics of independent random variables. We apply the main result to $k$-runs, U-statistics and subgraph counts in the Erdős–Rényi random graph. To prove our main result, we develop exponential concentration inequalities and higher-order tail probability expansions via Stein’s method. Full Article
der First-order covariance inequalities via Stein’s method By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Marie Ernst, Gesine Reinert, Yvik Swan. Source: Bernoulli, Volume 26, Number 3, 2051--2081.Abstract: We propose probabilistic representations for inverse Stein operators (i.e., solutions to Stein equations) under general conditions; in particular, we deduce new simple expressions for the Stein kernel. These representations allow to deduce uniform and nonuniform Stein factors (i.e., bounds on solutions to Stein equations) and lead to new covariance identities expressing the covariance between arbitrary functionals of an arbitrary univariate target in terms of a weighted covariance of the derivatives of the functionals. Our weights are explicit, easily computable in most cases and expressed in terms of objects familiar within the context of Stein’s method. Applications of the Cauchy–Schwarz inequality to these weighted covariance identities lead to sharp upper and lower covariance bounds and, in particular, weighted Poincaré inequalities. Many examples are given and, in particular, classical variance bounds due to Klaassen, Brascamp and Lieb or Otto and Menz are corollaries. Connections with more recent literature are also detailed. Full Article
der Convergence and concentration of empirical measures under Wasserstein distance in unbounded functional spaces By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Jing Lei. Source: Bernoulli, Volume 26, Number 1, 767--798.Abstract: We provide upper bounds of the expected Wasserstein distance between a probability measure and its empirical version, generalizing recent results for finite dimensional Euclidean spaces and bounded functional spaces. Such a generalization can cover Euclidean spaces with large dimensionality, with the optimal dependence on the dimensionality. Our method also covers the important case of Gaussian processes in separable Hilbert spaces, with rate-optimal upper bounds for functional data distributions whose coordinates decay geometrically or polynomially. Moreover, our bounds of the expected value can be combined with mean-concentration results to yield improved exponential tail probability bounds for the Wasserstein error of empirical measures under Bernstein-type or log Sobolev-type conditions. Full Article
der On frequentist coverage errors of Bayesian credible sets in moderately high dimensions By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Keisuke Yano, Kengo Kato. Source: Bernoulli, Volume 26, Number 1, 616--641.Abstract: In this paper, we study frequentist coverage errors of Bayesian credible sets for an approximately linear regression model with (moderately) high dimensional regressors, where the dimension of the regressors may increase with but is smaller than the sample size. Specifically, we consider quasi-Bayesian inference on the slope vector under the quasi-likelihood with Gaussian error distribution. Under this setup, we derive finite sample bounds on frequentist coverage errors of Bayesian credible rectangles. Derivation of those bounds builds on a novel Berry–Esseen type bound on quasi-posterior distributions and recent results on high-dimensional CLT on hyperrectangles. We use this general result to quantify coverage errors of Castillo–Nickl and $L^{infty}$-credible bands for Gaussian white noise models, linear inverse problems, and (possibly non-Gaussian) nonparametric regression models. In particular, we show that Bayesian credible bands for those nonparametric models have coverage errors decaying polynomially fast in the sample size, implying advantages of Bayesian credible bands over confidence bands based on extreme value theory. Full Article
der Weak convergence of quantile and expectile processes under general assumptions By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Tobias Zwingmann, Hajo Holzmann. Source: Bernoulli, Volume 26, Number 1, 323--351.Abstract: We show weak convergence of quantile and expectile processes to Gaussian limit processes in the space of bounded functions endowed with an appropriate semimetric which is based on the concepts of epi- and hypo- convergence as introduced in A. Bücher, J. Segers and S. Volgushev (2014), ‘ When Uniform Weak Convergence Fails: Empirical Processes for Dependence Functions and Residuals via Epi- and Hypographs ’, Annals of Statistics 42 . We impose assumptions for which it is known that weak convergence with respect to the supremum norm generally fails to hold. For quantiles, we consider stationary observations, where the marginal distribution function is assumed to be strictly increasing and continuous except for finitely many points and to admit strictly positive – possibly infinite – left- and right-sided derivatives. For expectiles, we focus on independent and identically distributed (i.i.d.) observations. Only a finite second moment and continuity at the boundary points but no further smoothness properties of the distribution function are required. We also show consistency of the bootstrap for this mode of convergence in the i.i.d. case for quantiles and expectiles. Full Article
der The story of Thomas & Ann Stone family : including Helping Hobart's Orphans, the King's Orphan School for Boys 1831-1836 / Alexander E.H. Stone. By www.catalog.slsa.sa.gov.au Published On :: King's Orphan Schools (New Town, Tas.) Full Article
der Item 02: William Hilton Saunders WWI diary, 1 January 1917 - 24 October 1917 By feedproxy.google.com Published On :: 19/03/2015 3:09:51 PM Full Article
der Item 04: William Hilton Saunders WWI diary, 18 February 1919 - 8 July 1919 By feedproxy.google.com Published On :: 19/03/2015 3:10:34 PM Full Article
der Item 03: William Hilton Saunders WWI diary, 1 January 1918 - 31 December 1918 By feedproxy.google.com Published On :: 19/03/2015 3:10:53 PM Full Article
der Item 01: William Hilton Saunders WWI diary, February 1916 - 2 January 1917 By feedproxy.google.com Published On :: 19/03/2015 3:11:14 PM Full Article
der Item 05: William Hilton Saunders WWI 1916-1919 address book with poetry By feedproxy.google.com Published On :: 19/03/2015 3:11:33 PM Full Article
der Item 07: A Journal of ye [the] Proceedings of his Majesty's Sloop Swallow, Captain Phillip [Philip] Carteret Commander, Commencing ye [the] 23 of July 1766 and ended [4 July 1767] By feedproxy.google.com Published On :: 5/05/2015 9:51:13 AM Full Article
der Item 08: A Logg [Log] Book of the proceedings on Board His Majesty's Ship Swallow, Captain Philip Carteret Commander Commencing from the 20th August 1766 and Ending [21st May 1768] By feedproxy.google.com Published On :: 5/05/2015 12:19:15 PM Full Article
der Federal watchdog finds 'reasonable grounds to believe' vaccine doctor's ouster was retaliation, lawyers say By news.yahoo.com Published On :: Fri, 08 May 2020 16:37:13 -0400 The Office of Special Counsel is recommending that ousted vaccine official Dr. Rick Bright be reinstated while it investigates his case, his lawyers announced Friday.Bright while leading coronavirus vaccine development was recently removed from his position as the director of the Department of Health and Human Services' Biomedical Advanced Research and Development Authority, and he alleges it was because he insisted congressional funding not go toward "drugs, vaccines, and other technologies that lack scientific merit" and limited the "broad use" of hydroxychloroquine after it was touted by President Trump. In a whistleblower complaint, he alleged "cronyism" at HHS. He has also alleged he was "pressured to ignore or dismiss expert scientific recommendations and instead to award lucrative contracts based on political connections."On Friday, Bright's lawyers said that the Office of Special Counsel has determined there are "reasonable grounds to believe" his firing was retaliation, The New York Times reports. The federal watchdog also recommended he be reinstated for 45 days to give the office "sufficient time to complete its investigation of Bright's allegations," CNN reports. The decision on whether to do so falls on Secretary of Health and Human Services Alex Azar, and Office of Special Counsel recommendations are "not binding," the Times notes. More stories from theweek.com Outed CIA agent Valerie Plame is running for Congress, and her launch video looks like a spy movie trailer 7 scathing cartoons about America's rush to reopen Trump says he couldn't have exposed WWII vets to COVID-19 because the wind was blowing the wrong way Full Article
der Chaffetz: I don't understand why Adam Schiff continues to have a security clearance By news.yahoo.com Published On :: Fri, 08 May 2020 14:43:30 -0400 Fox News contributor Jason Chaffetz and Andy McCarthy react to House Intelligence transcripts on Russia probe. Full Article
der Neighbor of father and son arrested in Ahmaud Arbery killing is also under investigation By news.yahoo.com Published On :: Fri, 08 May 2020 11:42:19 -0400 The ongoing investigation of the fatal shooting in Brunswick, Georgia, will also look at a neighbor of suspects Gregory and Travis McMichael who recorded video of the incident, authorities said. Full Article
der Bayesian Estimation Under Informative Sampling with Unattenuated Dependence By projecteuclid.org Published On :: Mon, 13 Jan 2020 04:00 EST Matthew R. Williams, Terrance D. Savitsky. Source: Bayesian Analysis, Volume 15, Number 1, 57--77.Abstract: An informative sampling design leads to unit inclusion probabilities that are correlated with the response variable of interest. However, multistage sampling designs may also induce higher order dependencies, which are ignored in the literature when establishing consistency of estimators for survey data under a condition requiring asymptotic independence among the unit inclusion probabilities. This paper constructs new theoretical conditions that guarantee that the pseudo-posterior, which uses sampling weights based on first order inclusion probabilities to exponentiate the likelihood, is consistent not only for survey designs which have asymptotic factorization, but also for survey designs that induce residual or unattenuated dependence among sampled units. The use of the survey-weighted pseudo-posterior, together with our relaxed requirements for the survey design, establish a wide variety of analysis models that can be applied to a broad class of survey data sets. Using the complex sampling design of the National Survey on Drug Use and Health, we demonstrate our new theoretical result on multistage designs characterized by a cluster sampling step that expresses within-cluster dependence. We explore the impact of multistage designs and order based sampling. Full Article
der Modeling Population Structure Under Hierarchical Dirichlet Processes By projecteuclid.org Published On :: Wed, 13 Mar 2019 22:00 EDT Lloyd T. Elliott, Maria De Iorio, Stefano Favaro, Kaustubh Adhikari, Yee Whye Teh. Source: Bayesian Analysis, Volume 14, Number 2, 313--339.Abstract: We propose a Bayesian nonparametric model to infer population admixture, extending the hierarchical Dirichlet process to allow for correlation between loci due to linkage disequilibrium. Given multilocus genotype data from a sample of individuals, the proposed model allows inferring and classifying individuals as unadmixed or admixed, inferring the number of subpopulations ancestral to an admixed population and the population of origin of chromosomal regions. Our model does not assume any specific mutation process, and can be applied to most of the commonly used genetic markers. We present a Markov chain Monte Carlo (MCMC) algorithm to perform posterior inference from the model and we discuss some methods to summarize the MCMC output for the analysis of population admixture. Finally, we demonstrate the performance of the proposed model in a real application, using genetic data from the ectodysplasin-A receptor (EDAR) gene, which is considered to be ancestry-informative due to well-known variations in allele frequency as well as phenotypic effects across ancestry. The structure analysis of this dataset leads to the identification of a rare haplotype in Europeans. We also conduct a simulated experiment and show that our algorithm outperforms parametric methods. Full Article
der Models as Approximations—Rejoinder By projecteuclid.org Published On :: Wed, 08 Jan 2020 04:00 EST Andreas Buja, Arun Kumar Kuchibhotla, Richard Berk, Edward George, Eric Tchetgen Tchetgen, Linda Zhao. Source: Statistical Science, Volume 34, Number 4, 606--620.Abstract: We respond to the discussants of our articles emphasizing the importance of inference under misspecification in the context of the reproducibility/replicability crisis. Along the way, we discuss the roles of diagnostics and model building in regression as well as connections between our well-specification framework and semiparametric theory. Full Article
der Rejoinder: Bayes, Oracle Bayes, and Empirical Bayes By projecteuclid.org Published On :: Thu, 18 Jul 2019 22:01 EDT Bradley Efron. Source: Statistical Science, Volume 34, Number 2, 234--235. Full Article
der Comment: Variational Autoencoders as Empirical Bayes By projecteuclid.org Published On :: Thu, 18 Jul 2019 22:01 EDT Yixin Wang, Andrew C. Miller, David M. Blei. Source: Statistical Science, Volume 34, Number 2, 229--233. Full Article
der Rejoinder: Response to Discussions and a Look Ahead By projecteuclid.org Published On :: Fri, 12 Apr 2019 04:00 EDT Vincent Dorie, Jennifer Hill, Uri Shalit, Marc Scott, Dan Cervone. Source: Statistical Science, Volume 34, Number 1, 94--99.Abstract: Response to discussion of Dorie (2017), in which the authors of that piece express their gratitude to the discussants, rebut some specific criticisms, and argue that the limitations of the 2016 Atlantic Causal Inference Competition represent an exciting opportunity for future competitions in a similar mold. Full Article
der Amazon Just Launched an Exclusive Clothing Collection Full of Warm and Comfy Basics Under $45 By www.health.com Published On :: Tue, 17 Dec 2019 12:23:05 -0500 The womenswear line is new, and there’s already a variety of items to shop. Full Article
der Metacognitive Mechanisms Underlying Lucid Dreaming By www.jneurosci.org Published On :: 2015-01-21 Elisa FilevichJan 21, 2015; 35:1082-1088BehavioralSystemsCognitive Full Article
der Brain-Derived Neurotrophic Factor Protection of Cortical Neurons from Serum Withdrawal-Induced Apoptosis Is Inhibited by cAMP By www.jneurosci.org Published On :: 2003-06-01 Steven PoserJun 1, 2003; 23:4420-4427Cellular Full Article
der Sleep Deprivation Biases the Neural Mechanisms Underlying Economic Preferences By www.jneurosci.org Published On :: 2011-03-09 Vinod VenkatramanMar 9, 2011; 31:3712-3718BehavioralSystemsCognitive Full Article
der A Transcriptome Database for Astrocytes, Neurons, and Oligodendrocytes: A New Resource for Understanding Brain Development and Function By www.jneurosci.org Published On :: 2008-01-02 John D. CahoyJan 2, 2008; 28:264-278Cellular Full Article
der Indigenous peoples and dementia : new understandings of memory loss and memory care By dal.novanet.ca Published On :: Fri, 1 May 2020 19:36:42 -0300 Callnumber: RC 521 I53 2019ISBN: 9780774837835 (hardcover) Full Article
der A Transcriptome Database for Astrocytes, Neurons, and Oligodendrocytes: A New Resource for Understanding Brain Development and Function By www.jneurosci.org Published On :: 2008-01-02 John D. CahoyJan 2, 2008; 28:264-278Cellular Full Article
der BIRTHDAY PARTY PACKAGE/ DROP-IN LEADERS By www.eastgwillimbury.ca Published On :: Sat, 13 Jul 2019 06:29:34 GMT Full Article
der È ora di accendere tutti i motori By www.bis.org Published On :: 2019-06-30T10:30:00Z Italian translation of the speech by Mr Agustín Carstens, General Manager of the BIS, on the occasion of the Bank's Annual General Meeting, Basel, 30 June 2019. Full Article
der È ora di accendere tutti i motori, afferma la BRI nella sua Relazione economica annuale By www.bis.org Published On :: 2019-06-30T10:30:00Z Italian translation of the BIS press release on the presentation of the Annual Economic Report 2019, 30 June 2019. Full Article
der Aprendizajes derivados de veinticinco años de autonomía del Banco de México By www.bis.org Published On :: 2019-11-22T14:45:00Z Discurso del Dr. Agustín Carstens, Director General del Banco de Pagos Internacionales, en la Celebración del 25 Aniversario de la Autonomía del Banco de México, Ciudad de México, 22 de noviembre de 2019. Full Article
der MakuluLinux Delivers Modernity With New Core Platform By www.technewsworld.com Published On :: 2020-05-08T10:56:00-07:00 If you are looking for a well-designed Linux distro that is far from mainstream, loaded with performance features not found elsewhere, check out the 2020 upgrade of the MakuluLinux Core distro. It could change your perspective on what a daily computing driver should offer. Developer Jacque Montague Raymer recently released the 2020 edition of MakuluLinux Core OS. Full Article
der A 6-Point Plan to Leapfrog to CX Leadership By www.crmbuyer.com Published On :: 2020-04-08T11:58:09-07:00 Customer experience as a boardroom topic is more relevant than ever. Enterprises are investing significant digital transformation budgets and commissioning large projects to elevate CX. Yet more than 70 percent of digital transformation projects fail to move the needle at scale. One topic that has a substantial impact on CX is the transformation of customer service operations using digital tools. Full Article
der The lawyer who laundered political contributions By www.mcclatchydc.com Published On :: Full Article
der Alaska Native Sisterhood civil rights leader Amy Hallingstad--a glimpse to 1947 By www.sealaskaheritage.org Published On :: Full Article
der Pattern Separation Underpins Expectation-Modulated Memory By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 Pattern separation and completion are fundamental hippocampal computations supporting memory encoding and retrieval. However, despite extensive exploration of these processes, it remains unclear whether and how top-down processes adaptively modulate the dynamics between these computations. Here we examine the role of expectation in shifting the hippocampus to perform pattern separation. In a behavioral task, 29 participants (7 males) learned a cue-object category contingency. Then, at encoding, one-third of the cues preceding the to-be-memorized objects, violated the studied rule. At test, participants performed a recognition task with old objects (targets) and a set of parametrically manipulated (very similar to dissimilar) foils for each object. Accuracy was found to be better for foils of high similarity to targets that were contextually unexpected at encoding compared with expected ones. Critically, there were no expectation-driven differences for targets and low similarity foils. To further explore these effects, we implemented a computational model of the hippocampus, performing the same task as the human participants. We used representational similarity analysis to examine how top-down expectation interacts with bottom-up perceptual input, in each layer. All subfields showed more dissimilar representations for unexpected items, with dentate gyrus (DG) and CA3 being more sensitive to expectation violation than CA1. Again, representational differences between expected and unexpected inputs were prominent for moderate to high levels of input similarity. This effect diminished when inputs from DG and CA3 into CA1 were lesioned. Overall, these novel findings strongly suggest that pattern separation in DG/CA3 underlies the effect that violation of expectation exerts on memory. SIGNIFICANCE STATEMENT What makes some events more memorable than others is a key question in cognitive neuroscience. Violation of expectation often leads to better memory performance, but the neural mechanism underlying this benefit remains elusive. In a behavioral study, we found that memory accuracy is enhanced selectively for unexpected highly similar foils, suggesting expectation violation does not enhance memory indiscriminately, but specifically aids the disambiguation of overlapping inputs. This is further supported by our subsequent investigation using a hippocampal computational model, revealing increased representational dissimilarity for unexpected highly similar foils in DG and CA3. These convergent results provide the first evidence that pattern separation plays an explicit role in supporting memory for unexpected information. Full Article
der Treatment with Mesenchymal-Derived Extracellular Vesicles Reduces Injury-Related Pathology in Pyramidal Neurons of Monkey Perilesional Ventral Premotor Cortex By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 Functional recovery after cortical injury, such as stroke, is associated with neural circuit reorganization, but the underlying mechanisms and efficacy of therapeutic interventions promoting neural plasticity in primates are not well understood. Bone marrow mesenchymal stem cell-derived extracellular vesicles (MSC-EVs), which mediate cell-to-cell inflammatory and trophic signaling, are thought be viable therapeutic targets. We recently showed, in aged female rhesus monkeys, that systemic administration of MSC-EVs enhances recovery of function after injury of the primary motor cortex, likely through enhancing plasticity in perilesional motor and premotor cortices. Here, using in vitro whole-cell patch-clamp recording and intracellular filling in acute slices of ventral premotor cortex (vPMC) from rhesus monkeys (Macaca mulatta) of either sex, we demonstrate that MSC-EVs reduce injury-related physiological and morphologic changes in perilesional layer 3 pyramidal neurons. At 14-16 weeks after injury, vPMC neurons from both vehicle- and EV-treated lesioned monkeys exhibited significant hyperexcitability and predominance of inhibitory synaptic currents, compared with neurons from nonlesioned control brains. However, compared with vehicle-treated monkeys, neurons from EV-treated monkeys showed lower firing rates, greater spike frequency adaptation, and excitatory:inhibitory ratio. Further, EV treatment was associated with greater apical dendritic branching complexity, spine density, and inhibition, indicative of enhanced dendritic plasticity and filtering of signals integrated at the soma. Importantly, the degree of EV-mediated reduction of injury-related pathology in vPMC was significantly correlated with measures of behavioral recovery. These data show that EV treatment dampens injury-related hyperexcitability and restores excitatory:inhibitory balance in vPMC, thereby normalizing activity within cortical networks for motor function. SIGNIFICANCE STATEMENT Neuronal plasticity can facilitate recovery of function after cortical injury, but the underlying mechanisms and efficacy of therapeutic interventions promoting this plasticity in primates are not well understood. Our recent work has shown that intravenous infusions of mesenchymal-derived extracellular vesicles (EVs) that are involved in cell-to-cell inflammatory and trophic signaling can enhance recovery of motor function after injury in monkey primary motor cortex. This study shows that this EV-mediated enhancement of recovery is associated with amelioration of injury-related hyperexcitability and restoration of excitatory-inhibitory balance in perilesional ventral premotor cortex. These findings demonstrate the efficacy of mesenchymal EVs as a therapeutic to reduce injury-related pathologic changes in the physiology and structure of premotor pyramidal neurons and support recovery of function. Full Article
der Basigin Associates with Integrin in Order to Regulate Perineurial Glia and Drosophila Nervous System Morphology By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 The Drosophila nervous system is ensheathed by a layer of outer glial cells, the perineurial glia, and a specialized extracellular matrix, the neural lamella. The function of perineurial glial cells and how they interact with the extracellular matrix are just beginning to be elucidated. Integrin-based focal adhesion complexes link the glial membrane to the extracellular matrix, but little is known about integrin's regulators in the glia. The transmembrane Ig domain protein Basigin/CD147/EMMPRIN is highly expressed in the perineurial glia surrounding the Drosophila larval nervous system. Here we show that Basigin associates with integrin at the focal adhesions to uphold the structure of the glia-extracellular matrix sheath. Knockdown of Basigin in perineurial glia using RNAi results in significant shortening of the ventral nerve cord, compression of the glia and extracellular matrix in the peripheral nerves, and reduction in larval locomotion. We determined that Basigin is expressed in close proximity to integrin at the glial membrane, and that expression of the extracellular integrin-binding domain of Basigin is sufficient to rescue peripheral glial compression. We also found that a reduction in expression of integrin at the membrane rescues the ventral nerve cord shortening, peripheral glial compression, and locomotor phenotypes, and that reduction in the integrin-binding protein Talin can partially rescue glial compression. These results identify Basigin as a potential negative regulator of integrin in the glia, supporting proper glial and extracellular matrix ensheathment of the nervous system. SIGNIFICANCE STATEMENT The glial cells and extracellular matrix play important roles in supporting and protecting the nervous system, but the interactions between these components have not been well characterized. Our study identified expression of a conserved Ig superfamily protein, Basigin, at the glial membrane of Drosophila where it associates with the integrin-based focal adhesion complexes to ensure proper ensheathment of the CNS and PNS. Loss of Basigin in the glia results in an overall compression of the nervous system due to integrin dysregulation, which causes locomotor defects in the animals. This underlies the importance of glia-matrix communication for structural and functional support of the nervous system. Full Article
der The VGF-derived Peptide TLQP21 Impairs Purinergic Control of Chemotaxis and Phagocytosis in Mouse Microglia By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 Microglial cells are considered as sensors of brain pathology by detecting any sign of brain lesions, infections, or dysfunction and can influence the onset and progression of neurological diseases. They are capable of sensing their neuronal environment via many different signaling molecules, such as neurotransmitters, neurohormones and neuropeptides. The neuropeptide VGF has been associated with many metabolic and neurological disorders. TLQP21 is a VGF-derived peptide and has been shown to signal via C3aR1 and C1qBP receptors. The effect of TLQP21 on microglial functions in health or disease is not known. Studying microglial cells in acute brain slices, we found that TLQP21 impaired metabotropic purinergic signaling. Specifically, it attenuated the ATP-induced activation of a K+ conductance, the UDP-stimulated phagocytic activity, and the ATP-dependent laser lesion-induced process outgrowth. These impairments were reversed by blocking C1qBP, but not C3aR1 receptors. While microglia in brain slices from male mice lack C3aR1 receptors, both receptors are expressed in primary cultured microglia. In addition to the negative impact on purinergic signaling, we found stimulating effects of TLQP21 in cultured microglia, which were mediated by C3aR1 receptors: it directly evoked membrane currents, stimulated basal phagocytic activity, evoked intracellular Ca2+ transient elevations, and served as a chemotactic signal. We conclude that TLQP21 has differential effects on microglia depending on C3aR1 activation or C1qBP-dependent attenuation of purinergic signaling. Thus, TLQP21 can modulate the functional phenotype of microglia, which may have an impact on their function in health and disease. SIGNIFICANCE STATEMENT The neuropeptide VGF and its peptides have been associated with many metabolic and neurological disorders. TLQP21 is a VGF-derived peptide that activates C1qBP receptors, which are expressed by microglia. We show here, for the first time, that TLQP21 impairs P2Y-mediated purinergic signaling and related functions. These include modulation of phagocytic activity and responses to injury. As purinergic signaling is central for microglial actions in the brain, this TLQP21-mediated mechanism might regulate microglial activity in health and disease. We furthermore show that, in addition to C1qBP, functional C3aR1 responses contribute to TLQP21 action on microglia. However, C3aR1 responses were only present in primary cultures but not in situ, suggesting that the expression of these receptors might vary between different microglial activation states. Full Article
der Field tests under way for new hunger-measuring tool By www.fao.org Published On :: Tue, 20 Aug 2013 01:00:00 GMT FAO has begun field tests for a new approach to measuring hunger and food insecurity – part of a collaboration with polling specialists Gallup, Inc. The project – known as Voices of the Hungry – is based on a “food insecurity experience scale,” with annual data collected using eight interview questions about people’s experiences of food insecurity over the preceding [...] Full Article