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https://www.readbyqxmd.com/read/28628647/an-efficient-coding-theory-for-a-dynamic-trajectory-predicts-non-uniform-allocation-of-entorhinal-grid-cells-to-modules
#1
Noga Mosheiff, Haggai Agmon, Avraham Moriel, Yoram Burak
Grid cells in the entorhinal cortex encode the position of an animal in its environment with spatially periodic tuning curves with different periodicities. Recent experiments established that these cells are functionally organized in discrete modules with uniform grid spacing. Here we develop a theory for efficient coding of position, which takes into account the temporal statistics of the animal's motion. The theory predicts a sharp decrease of module population sizes with grid spacing, in agreement with the trend seen in the experimental data...
June 19, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28628104/active-dendritic-integration-as-a-mechanism-for-robust-and-precise-grid-cell-firing
#2
Christoph Schmidt-Hieber, Gabija Toleikyte, Laurence Aitchison, Arnd Roth, Beverley A Clark, Tiago Branco, Michael Häusser
Understanding how active dendrites are exploited for behaviorally relevant computations is a fundamental challenge in neuroscience. Grid cells in medial entorhinal cortex are an attractive model system for addressing this question, as the computation they perform is clear: they convert synaptic inputs into spatially modulated, periodic firing. Whether active dendrites contribute to the generation of the dual temporal and rate codes characteristic of grid cell output is unknown. We show that dendrites of medial entorhinal cortex neurons are highly excitable and exhibit a supralinear input-output function in vitro, while in vivo recordings reveal membrane potential signatures consistent with recruitment of active dendritic conductances...
June 19, 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/28599195/evaluation-of-a-data-fusion-approach-to-estimate-daily-pm2-5-levels-in-north-china
#3
Fengchao Liang, Meng Gao, Qingyang Xiao, Gregory R Carmichael, Xiaochuan Pan, Yang Liu
PM2.5 air pollution has been a growing concern worldwide. Previous studies have conducted several techniques to estimate PM2.5 exposure spatiotemporally in China, but all these have limitations. This study was to develop a data fusion approach and compare it with kriging and Chemistry Module. Two techniques were applied to create daily spatial cover of PM2.5 in grid cells with a resolution of 10km in North China in 2013, respectively, which was kriging with an external drift (KED) and Weather Research and Forecast Model with Chemistry Module (WRF-Chem)...
June 6, 2017: Environmental Research
https://www.readbyqxmd.com/read/28593558/combined-effect-of-pulse-density-and-grid-cell-size-on-predicting-and-mapping-aboveground-carbon-in-fast-growing-eucalyptus-forest-plantation-using-airborne-lidar-data
#4
Carlos Alberto Silva, Andrew Thomas Hudak, Carine Klauberg, Lee Alexandre Vierling, Carlos Gonzalez-Benecke, Samuel de Padua Chaves Carvalho, Luiz Carlos Estraviz Rodriguez, Adrián Cardil
BACKGROUND: LiDAR remote sensing is a rapidly evolving technology for quantifying a variety of forest attributes, including aboveground carbon (AGC). Pulse density influences the acquisition cost of LiDAR, and grid cell size influences AGC prediction using plot-based methods; however, little work has evaluated the effects of LiDAR pulse density and cell size for predicting and mapping AGC in fast-growing Eucalyptus forest plantations. The aim of this study was to evaluate the effect of LiDAR pulse density and grid cell size on AGC prediction accuracy at plot and stand-levels using airborne LiDAR and field data...
December 2017: Carbon Balance and Management
https://www.readbyqxmd.com/read/28593193/differential-expression-and-cell-type-specificity-of-perineuronal-nets-in-hippocampus-medial-entorhinal-cortex-and-visual-cortex-examined-in-the-rat-and-mouse
#5
Kristian Kinden Lensjø, Ane Charlotte Christensen, Simen Tennøe, Marianne Fyhn, Torkel Hafting
Perineuronal nets (PNNs) are specialized extracellular matrix (ECM) structures that condense around the soma and proximal dendrites of subpopulations of neurons. Emerging evidence suggests that they are involved in regulating brain plasticity. However, the expression of PNNs varies between and within brain areas. A lack of quantitative studies describing the distribution and cell-specificity of PNNs makes it difficult to reveal the functional roles of PNNs. In the current study, we examine the distribution of PNNs and the identity of PNN-enwrapped neurons in three brain areas with different cognitive functions: the dorsal hippocampus, medial entorhinal cortex (mEC) and primary visual cortex (V1)...
May 2017: ENeuro
https://www.readbyqxmd.com/read/28591796/histamine-enhances-theta-coupled-spiking-and-gamma-oscillations-in-the-medial-entorhinal-cortex-consistent-with-successful-spatial-recognition
#6
Quanhui Chen, Fenlan Luo, Faguo Yue, Jianxia Xia, Qin Xiao, Xiang Liao, Jun Jiang, Jun Zhang, Bo Hu, Dong Gao, Chao He, Zhian Hu
Encoding of spatial information in the superficial layers of the medial entorhinal cortex (sMEC) involves theta-modulated spiking and gamma oscillations, as well as spatially tuned grid cells and border cells. Little is known about the role of the arousal-promoting histaminergic system in the modification of information encoded in the sMEC in vivo, and how such histamine-regulated information correlates with behavioral functions. Here, we show that histamine upregulates the neural excitability of a significant proportion of neurons (16...
June 7, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28590592/decadal-changes-in-habitat-characteristics-influence-population-trajectories-of-southern-elephant-seals
#7
Mark A Hindell, Michael Sumner, Sophie Bestley, Simon Wotherspoon, Robert G Harcourt, Mary-Anne Lea, Rachael Alderman, Clive R McMahon
Understanding divergent biological responses to climate change is important for predicting ecosystem level consequences. We use species habitat models to predict the winter foraging habitats of female southern elephant seals and investigate how changes in environmental variables within these habitats may be related to observed decreases in the Macquarie Island population. There were three main groups of seals that specialised in different ocean realms (the sub-Antarctic, the Ross Sea and the Victoria Land Coast)...
June 7, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28561343/pan-arctic-sea-ice-algal-chl-a-biomass-and-suitable-habitat-are-largely-underestimated-for-multiyear-ice
#8
Benjamin A Lange, Hauke Flores, Christine Michel, Justin F Beckers, Anne Bublitz, John Alec Casey, Giulia Castellani, Ido Hatam, Anke Reppchen, Svenja A Rudolph, Christian Haas
There is mounting evidence that multiyear ice (MYI) is a unique component of the Arctic Ocean and may play a more important ecological role than previously assumed. This study improves our understanding of the potential of MYI as a suitable habitat for sea ice algae on a pan-Arctic scale. We sampled sea ice cores from MYI and first-year sea ice (FYI) within the Lincoln Sea during four consecutive spring seasons. This included four MYI hummocks with a mean chl a biomass of 2.0 mg/m(2) , a value significantly higher than FYI and MYI refrozen ponds...
May 31, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28533968/changes-in-the-spatial-and-temporal-pattern-of-natural-forest-cover-on-hainan-island-from-the-1950s-to-the-2010s-implications-for-natural-forest-conservation-and-management
#9
Siliang Lin, Yaozhu Jiang, Jiekun He, Guangzhi Ma, Yang Xu, Haisheng Jiang
The study of the past, present, and future state and dynamics of the tropical natural forest cover (NFC) might help to better understand the pattern of deforestation and fragmentation as well as the influence of social and natural processes. The obtained information will support the development of effective conservation policies and strategies. In the present study, we used historical data of the road network, topography, and climatic productivity to reconstruct NFC maps of Hainan Island, China, from the 1950s to the 2010s, using the random forest algorithm...
2017: PeerJ
https://www.readbyqxmd.com/read/28515661/improving-large-area-population-mapping-using-geotweet-densities
#10
Nirav N Patel, Forrest R Stevens, Zhuojie Huang, Andrea E Gaughan, Iqbal Elyazar, Andrew J Tatem
Many different methods are used to disaggregate census data and predict population densities to construct finer scale, gridded population data sets. These methods often involve a range of high resolution geospatial covariate datasets on aspects such as urban areas, infrastructure, land cover and topography; such covariates, however, are not directly indicative of the presence of people. Here we tested the potential of geo-located tweets from the social media application, Twitter, as a covariate in the production of population maps...
April 2017: Transactions in GIS: TG
https://www.readbyqxmd.com/read/28511360/refined-2013-based-vehicle-emission-inventory-and-its-spatial-and-temporal-characteristics-in-zhengzhou-china
#11
Mimi Gong, Shasha Yin, Xingke Gu, Yuanqian Xu, Nan Jiang, Ruiqin Zhang
Vehicle emission is becoming one of the most important pollution sources because of the increase in vehicle population and activity in China. A more reasonable and complete vehicle emission inventory in Zhengzhou for the year 2013 was developed in this study. This inventory is suitable for local emission factors and vehicle kilometers of travel. Estimates show that the total carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOX), particulate matter (PM2.5 and PM10) and sulfur dioxide (SO2) emissions were 291Gg, 35Gg, 106Gg, 6Gg, 7Gg, and 3Gg, respectively...
December 1, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28494861/excitatory-microcircuits-within-superficial-layers-of-the-medial-entorhinal-cortex
#12
Jochen Winterer, Nikolaus Maier, Christian Wozny, Prateep Beed, Jörg Breustedt, Roberta Evangelista, Yangfan Peng, Tiziano D'Albis, Richard Kempter, Dietmar Schmitz
The distinctive firing pattern of grid cells in the medial entorhinal cortex (MEC) supports its role in the representation of space. It is widely believed that the hexagonal firing field of grid cells emerges from neural dynamics that depend on the local microcircuitry. However, local networks within the MEC are still not sufficiently characterized. Here, applying up to eight simultaneous whole-cell recordings in acute brain slices, we demonstrate the existence of unitary excitatory connections between principal neurons in the superficial layers of the MEC...
May 9, 2017: Cell Reports
https://www.readbyqxmd.com/read/28467409/a-pilot-study-to-delimit-tsetse-target-populations-in-zimbabwe
#13
Gerald Chikowore, Ahmadou H Dicko, Peter Chinwada, Moses Zimba, William Shereni, François Roger, Jérémy Bouyer, Laure Guerrini
BACKGROUND: Tsetse (Glossina sensu stricto) are cyclical vectors of human and animal trypanosomoses, that are presently targeted by the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) coordinated by the African Union. In order to achieve effective control of tsetse, there is need to produce elaborate plans to guide intervention programmes. A model intended to aid in the planning of intervention programmes and assist a fuller understanding of tsetse distribution was applied, in a pilot study in the Masoka area, Mid-Zambezi valley in Zimbabwe, and targeting two savannah species, Glossina morsitans morsitans and Glossina pallidipes...
May 2017: PLoS Neglected Tropical Diseases
https://www.readbyqxmd.com/read/28454032/identifying-spatial-clusters-of-flood-exposure-to-support-decision-making-in-risk-management
#14
Veronika Röthlisberger, Andreas P Zischg, Margreth Keiler
A sound understanding of flood risk drivers (hazard, exposure and vulnerability) is essential for the effective and efficient implementation of risk-reduction strategies. In this paper, we focus on 'exposure' and study the influence of different methods and parameters of flood exposure analyses in Switzerland. We consider two types of exposure indicators and two different spatial aggregation schemes: the density of exposed assets (exposed numbers per km(2)) and the ratios of exposed assets (share of exposed assets compared to total amount of assets in a specific region) per municipality and per grid cells of similar size as the municipalities...
November 15, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28450227/spatial-phylogenetics-of-the-vascular-flora-of-chile
#15
Rosa A Scherson, Andrew H Thornhill, Rafael Urbina-Casanova, William A Freyman, Patricio A Pliscoff, Brent D Mishler
Current geographic patterns of biodiversity are a consequence of the evolutionary history of the lineages that comprise them. This study was aimed at exploring how evolutionary features of the vascular flora of Chile are distributed across the landscape. Using a phylogeny at the genus level for 87% of the Chilean vascular flora, and a geographic database of sample localities, we calculated phylogenetic diversity (PD), phylogenetic endemism (PE), relative PD (RPD), and relative PE (RPE). Categorical Analyses of Neo- and Paleo-Endemism (CANAPE) were also performed, using a spatial randomization to assess statistical significance...
April 24, 2017: Molecular Phylogenetics and Evolution
https://www.readbyqxmd.com/read/28448253/a-map-of-abstract-relational-knowledge-in-the-human-hippocampal-entorhinal-cortex
#16
Mona M Garvert, Raymond J Dolan, Timothy Ej Behrens
The hippocampal-entorhinal system encodes a map of space that guides spatial navigation. Goal-directed behaviour outside of spatial navigation similarly requires a representation of abstract forms of relational knowledge. This information relies on the same neural system, but it is not known whether the organisational principles governing continuous maps may extend to the implicit encoding of discrete, non-spatial graphs. Here, we show that the human hippocampal-entorhinal system can represent relationships between objects using a metric that depends on associative strength...
April 27, 2017: ELife
https://www.readbyqxmd.com/read/28424398/-brodmann-areas-27-28-36-and-37-the-parahippocampal-and-the-fusiform-gyri
#17
Satoshi Eifuku
First, Brodmann areas 27, 28, 36 and 37, were anatomically defined in the beginning of this review. These areas exist in the parahippocampal or fusiform gyrus of the ventral temporal lobe in humans. Subsequently, the current understanding of their functions was summarized on the basis of recent findings mainly through human functional neuroimaging studies and animal studies. Rodent studies have shown the existence of neuronal activities for representing space, such as those involving head-direction cells or grid cells, in areas 27 (the parasubicular cortex) and 28 (the ventral entorhinal cortex)...
April 2017: Brain and Nerve, Shinkei Kenkyū No Shinpo
https://www.readbyqxmd.com/read/28418593/nonparametric-tree-based-predictive-modeling-of-storm-outages-on-an-electric-distribution-network
#18
Jichao He, David W Wanik, Brian M Hartman, Emmanouil N Anagnostou, Marina Astitha, Maria E B Frediani
This article compares two nonparametric tree-based models, quantile regression forests (QRF) and Bayesian additive regression trees (BART), for predicting storm outages on an electric distribution network in Connecticut, USA. We evaluated point estimates and prediction intervals of outage predictions for both models using high-resolution weather, infrastructure, and land use data for 89 storm events (including hurricanes, blizzards, and thunderstorms). We found that spatially BART predicted more accurate point estimates than QRF...
March 2017: Risk Analysis: An Official Publication of the Society for Risk Analysis
https://www.readbyqxmd.com/read/28396399/context-dependent-spatially-periodic-activity-in-the-human-entorhinal-cortex
#19
Zoltan Nadasdy, T Peter Nguyen, Ágoston Török, Jason Y Shen, Deborah E Briggs, Pradeep N Modur, Robert J Buchanan
The spatially periodic activity of grid cells in the entorhinal cortex (EC) of the rodent, primate, and human provides a coordinate system that, together with the hippocampus, informs an individual of its location relative to the environment and encodes the memory of that location. Among the most defining features of grid-cell activity are the 60° rotational symmetry of grids and preservation of grid scale across environments. Grid cells, however, do display a limited degree of adaptation to environments. It remains unclear if this level of environment invariance generalizes to human grid-cell analogs, where the relative contribution of visual input to the multimodal sensory input of the EC is significantly larger than in rodents...
April 25, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28392071/a-multiplexed-heterogeneous-and-adaptive-code-for-navigation-in-medial-entorhinal-cortex
#20
Kiah Hardcastle, Niru Maheswaranathan, Surya Ganguli, Lisa M Giocomo
Medial entorhinal grid cells display strikingly symmetric spatial firing patterns. The clarity of these patterns motivated the use of specific activity pattern shapes to classify entorhinal cell types. While this approach successfully revealed cells that encode boundaries, head direction, and running speed, it left a majority of cells unclassified, and its pre-defined nature may have missed unconventional, yet important coding properties. Here, we apply an unbiased statistical approach to search for cells that encode navigationally relevant variables...
April 19, 2017: Neuron
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