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https://www.readbyqxmd.com/read/28777606/hippocampal-spike-timing-correlations-lead-to-hexagonal-grid-fields
#1
Mauro M Monsalve-Mercado, Christian Leibold
Space is represented in the mammalian brain by the activity of hippocampal place cells, as well as in their spike-timing correlations. Here, we propose a theory for how this temporal code is transformed to spatial firing rate patterns via spike-timing-dependent synaptic plasticity. The resulting dynamics of synaptic weights resembles well-known pattern formation models in which a lateral inhibition mechanism gives rise to a Turing instability. We identify parameter regimes in which hexagonal firing patterns develop as they have been found in medial entorhinal cortex...
July 21, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28769779/size-matters-how-scaling-affects-the-interaction-between-grid-and-border-cells
#2
Diogo Santos-Pata, Riccardo Zucca, Sock C Low, Paul F M J Verschure
Many hippocampal cell types are characterized by a progressive increase in scale along the dorsal-to-ventral axis, such as in the cases of head-direction, grid and place cells. Also located in the medial entorhinal cortex (MEC), border cells would be expected to benefit from such scale modulations. However, this phenomenon has not been experimentally observed. Grid cells in the MEC of mammals integrate velocity related signals to map the environment with characteristic hexagonal tessellation patterns. Due to the noisy nature of these input signals, path integration processes tend to accumulate errors as animals explore the environment, leading to a loss of grid-like activity...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28768062/self-organization-of-modular-activity-of-grid-cells
#3
Eugenio Urdapilleta, Bailu Si, Alessandro Treves
A unique topographical representation of space is found in the concerted activity of grid cells in the rodent medial entorhinal cortex. Many among the principal cells in this region exhibit a hexagonal firing pattern, in which each cell expresses its own set of place fields (spatial phases) at the vertices of a triangular grid, the spacing and orientation of which are typically shared with neighboring cells. Grid spacing, in particular, has been found to increase along the dorso-ventral axis of the entorhinal cortex but in discrete steps, i...
August 2, 2017: Hippocampus
https://www.readbyqxmd.com/read/28767717/disentangling-the-influence-of-environmental-and-anthropogenic-factors-on-the-distribution-of-endemic-vascular-plants-in-sardinia
#4
Mauro Fois, Giuseppe Fenu, Eva Maria Cañadas, Gianluigi Bacchetta
Due to the impelling urgency of plant conservation and the increasing availability of high resolution spatially interpolated (e.g. climate variables) and categorical data (e.g. land cover and vegetation type), many recent studies have examined relationships among plant species distributions and a diversified set of explanatory factors; nevertheless, global and regional patterns of endemic plant richness remain in many cases unexplained. One such pattern is the 294 endemic vascular plant taxa recorded on a 1 km resolution grid on the environmentally heterogeneous island of Sardinia...
2017: PloS One
https://www.readbyqxmd.com/read/28767687/a-novel-on-line-spatial-temporal-k-anonymity-method-for-location-privacy-protection-from-sequence-rules-based-inference-attacks
#5
Haitao Zhang, Chenxue Wu, Zewei Chen, Zhao Liu, Yunhong Zhu
Analyzing large-scale spatial-temporal k-anonymity datasets recorded in location-based service (LBS) application servers can benefit some LBS applications. However, such analyses can allow adversaries to make inference attacks that cannot be handled by spatial-temporal k-anonymity methods or other methods for protecting sensitive knowledge. In response to this challenge, first we defined a destination location prediction attack model based on privacy-sensitive sequence rules mined from large scale anonymity datasets...
2017: PloS One
https://www.readbyqxmd.com/read/28763654/evaluating-the-risk-of-phosphorus-loss-with-a-distributed-watershed-model-featuring-zero-order-mobilization-and-first-order-delivery
#6
Sisi Li, Liang Zhang, Hongbin Liu, Hugo A Loáiciga, Limei Zhai, Yanhua Zhuang, Qiuliang Lei, Wanli Hu, Wenchao Li, Qi Feng, Yun Du
Many semi-distributed models that simulate pollutants' losses from watersheds do not handle well detailed spatially distributed and temporal data with which to identify accurate and cost-effective strategies for controlling pollutants issuing from non-point sources. Such models commonly overlook the flow pathways of pollutants across the landscape. This work aims at closing such knowledge gap by developing a Spatially and Temporally Distributed Empirical model for Phosphorus Management (STEM-P) that simulates the daily phosphorus loss from source areas to receiving waters on a spatially-distributed grid-cell basis...
July 27, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28762959/mechanical-properties-and-cell-culture-characteristics-of-polycaprolactone-kagome-structure-scaffold-fabricated-by-precision-extruding-deposition-system
#7
Se-Hwan Lee, Yong Sang Cho, Myoung Wha Hong, Bu Kyu Lee, Yong-Doo Park, Sang-Hyug Park, Young-Yul Kim, Young-Sam Cho
To date, to enhance the mechanical properties of three-dimensional scaffolds used for bone regeneration in tissue engineering, many researchers have tried in the viewpoint of structure and chemistry. Meanwhile, in the structural engineering field, the kagome structure has been known as an excellent relative strength. In this study, to enhance the mechanical properties of a synthetic polymer scaffold used for tissue engineering, we applied the three-dimensional kagome structure to a porous scaffold for bone regeneration...
August 1, 2017: Biomedical Materials
https://www.readbyqxmd.com/read/28756950/grid-cells-encode-local-positional-information
#8
Revekka Ismakov, Omri Barak, Kate Jeffery, Dori Derdikman
The brain has an extraordinary ability to create an internal spatial map of the external world [1]. This map-like representation of environmental surroundings is encoded through specific types of neurons, located within the hippocampus and entorhinal cortex, which exhibit spatially tuned firing patterns [2, 3]. In addition to encoding space, these neurons are believed to be related to contextual information and memory [4-7]. One class of such cells is the grid cells, which are located within the entorhinal cortex, presubiculum, and parasubiculum [3, 8]...
August 7, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28750005/from-grid-cells-to-place-cells-with-realistic-field-sizes
#9
Torsten Neher, Amir Hossein Azizi, Sen Cheng
While grid cells in the medial entorhinal cortex (MEC) of rodents have multiple, regularly arranged firing fields, place cells in the cornu ammonis (CA) regions of the hippocampus mostly have single spatial firing fields. Since there are extensive projections from MEC to the CA regions, many models have suggested that a feedforward network can transform grid cell firing into robust place cell firing. However, these models generate place fields that are consistently too small compared to those recorded in experiments...
2017: PloS One
https://www.readbyqxmd.com/read/28748383/is-ambient-heat-exposure-levels-associated-with-miscarriage-or-stillbirths-in-hot-regions-a-cross-sectional-study-using-survey-data-from-the-ghana-maternal-health-survey-2007
#10
Benedict Asamoah, Tord Kjellstrom, Per-Olof Östergren
It is well established that high ambient heat could cause congenital abnormalities resulting in miscarriage or stillbirth among certain species of mammals. However, this has not been systematically studied in real field settings among humans, despite the potential value of such knowledge for estimating the impact of global warming on the human species. This study sought to test the hypothesis that maternal heat exposure during pregnancy in hot regions is associated with increased prevalence of spontaneous abortions or stillbirths and to develop an analytical strategy to use existing data from maternal health surveys and existing data on historical heat levels at a geographic grid cell level...
July 26, 2017: International Journal of Biometeorology
https://www.readbyqxmd.com/read/28742058/ito-with-embedded-silver-grids-as-transparent-conductive-electrodes-for-large-area-organic-solar-cells
#11
Bhushan Ramesh Patil, Mina Mirsafaei, Pawel Piotr Cielecki, Andre Luis Fernandes Cauduro, Jacek Fiutowski, Horst-Guenter Rubahn, Morten Madsen
In this work, development of semi-transparent electrodes for efficient large area organic solar cells (OSCs) has been demonstrated. Electron beam evaporated silver grids were embedded in commercially available ITO coatings on glass, through a standard negative photolithography process, in order to improve the conductivity of planar ITO substrates. The fabricated electrodes with embedded line and square patterned Ag grids reduced the sheet resistance of ITO by 25 % and 40 %, respectively, showing optical transmittance drops of less than 6 % within the complete visible light spectrum for both patterns...
July 25, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28742040/an-hp-adaptive-discretization-algorithm-for-signed-distance-field-generation
#12
Dan Koschier, Crispin Deul, Magnus Brand, Jan Bender
In this paper we present an hp-adaptive algorithm to generate discrete higher-order polynomial Signed Distance Fields (SDFs) on axis-aligned hexahedral grids from manifold polygonal input meshes. Using an orthonormal polynomial basis, we efficiently fit the polynomials to the underlying signed distance function on each cell. The proposed error-driven construction algorithm is globally adaptive and iteratively refines the SDFs using either spatial subdivision ( h-refinement) following an octree scheme or by cell-wise adaption of the polynomial approximation's degree ( p-refinement)...
July 21, 2017: IEEE Transactions on Visualization and Computer Graphics
https://www.readbyqxmd.com/read/28739165/quantitative-models-of-feline-lumbosacral-dorsal-root-ganglia-neuronal-cell-density
#13
Anastasia K Ostrowski, Zachariah J Sperry, Grant Kulik, Tim M Bruns
BACKGROUND: Dorsal root ganglia (DRG) are spinal root components that contain the cell bodies of converging primary sensory neurons. DRG are becoming a therapeutic target for electrical neural interfaces. Our purpose was to establish methods for quantifying the non-random nature and distribution of neuronal cell bodies within DRG. NEW METHOD: We identified neuronal cell body locations in 26 feline lumbosacral DRG cross-section histological images and used computational tools to quantify spatial trends...
July 21, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28731409/assessment-of-the-probability-of-autochthonous-transmission-of-chikungunya-virus-in-canada-under-recent-and-projected-climate-change
#14
Victoria Ng, Aamir Fazil, Philippe Gachon, Guillaume Deuymes, Milka Radojević, Mariola Mascarenhas, Sophiya Garasia, Michael A Johansson, Nicholas H Ogden
BACKGROUND: Chikungunya virus (CHIKV) is a reemerging pathogen transmitted by Aedes aegypti and Aedes albopictus mosquitoes. The ongoing Caribbean outbreak is of concern due to the potential for infected travelers to spread the virus to countries where vectors are present and the population is susceptible. Although there has been no autochthonous transmission of CHIKV in Canada, there is concern that both Ae. albopictus and CHIKV will become established, particularly under projected climate change...
June 5, 2017: Environmental Health Perspectives
https://www.readbyqxmd.com/read/28727387/focal-cryotherapy-step-by-step-technique-description
#15
Cristina Redondo, Victor Srougi, José Batista da Costa, Mohammed Baghdad, Guillermo Velilla, Igor Nunes-Silva, Sebastien Bergerat, Silvia Garcia-Barreras, François Rozet, Alexandre Ingels, Marc Galiano, Rafael Sanchez-Salas, Eric Barret, Xavier Cathelineau
INTRODUCTION AND OBJECTIVE: Focal cryotherapy emerged as an efficient option to treat favorable and localized prostate cancer (PCa). The purpose of this video is to describe the procedure step by step. MATERIALS AND METHODS: We present the case of a 68 year-old man with localized PCa in the anterior aspect of the prostate. RESULTS: The procedure is performed under general anesthesia, with the patient in lithotomy position. Briefly, the equipament utilized includes the cryotherapy console coupled with an ultrasound system, argon and helium gas bottles, cryoprobes, temperature probes and an urethral warming catheter...
July 20, 2017: International Braz J Urol: Official Journal of the Brazilian Society of Urology
https://www.readbyqxmd.com/read/28724433/gridsample-an-r-package-to-generate-household-survey-primary-sampling-units-psus-from-gridded-population-data
#16
Dana R Thomson, Forrest R Stevens, Nick W Ruktanonchai, Andrew J Tatem, Marcia C Castro
BACKGROUND: Household survey data are collected by governments, international organizations, and companies to prioritize policies and allocate billions of dollars. Surveys are typically selected from recent census data; however, census data are often outdated or inaccurate. This paper describes how gridded population data might instead be used as a sample frame, and introduces the R GridSample algorithm for selecting primary sampling units (PSU) for complex household surveys with gridded population data...
July 19, 2017: International Journal of Health Geographics
https://www.readbyqxmd.com/read/28708881/large-anthropogenic-impacts-on-a-charismatic-small-carnivore-insights-from-distribution-surveys-of-red-panda-ailurus-fulgens-in-nepal
#17
Saroj Panthi, Gopal Khanal, Krishna Prasad Acharya, Achyut Aryal, Arjun Srivathsa
Protected areas are key to preserving biodiversity and maintaining ecosystem services. However, their ability to ensure long-term survival of threatened andendangered species varies across countries, regions and landscapes. Distribution surveys can beparticularly important for assessing the value of protected areas, and gauging their efficacy incatering to species-specific requirements. We assessed the conservation value of one such reserve for a charismatic yet globally endangered species, the red panda Ailurus fulgens,in the light of on-going land-use transformation in Nepal...
2017: PloS One
https://www.readbyqxmd.com/read/28703324/scaling-range-sizes-to-threats-for-robust-predictions-of-risks-to-biodiversity
#18
David A Keith, H Resit Akçakaya, Nicholas J Murray
Assessments of risk to biodiversity often rely on spatial distributions of species and ecosystems. Range size metrics used extensively in these assessments, such as Area of Occupancy (AOO), are sensitive to measurement scale, prompting proposals to measure them at finer scales, or a variery of different scales based on the shape of the distribution or ecological characteristics of the biota. Despite its dominant role in Red List assessments for decades, appropriate spatial scales of AOO for predicting risks of species extinction or ecosystem collapse remain untested and contentious...
July 13, 2017: Conservation Biology: the Journal of the Society for Conservation Biology
https://www.readbyqxmd.com/read/28701481/place-and-grid-cells-in-a-loop-implications-for-memory-function-and-spatial-coding
#19
César Rennó-Costa, Adriano B L Tort
Place cells in the hippocampus and grid cells in the medial entorhinal cortex have different codes for space. However, how one code relates to the other is ill understood. Based on the anatomy of the entorhinal-hippocampal circuitry, we constructed a model of place and grid cells organized in a loop to investigate their mutual influence in the establishment of their codes for space. Using computer simulations, we first replicated experiments in rats that measured place and grid cell activity in different environments, and then assessed which features of the model account for different phenomena observed in neurophysiological data, such as pattern completion and pattern separation, global and rate remapping of place cells and realignment of grid cells...
July 12, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28694754/using-curcumin-to-prevent-structural-and-behavioral-changes-of-medial-prefrontal-cortex-induced-by-sleep-deprivation-in-rats
#20
Ali Noorafshan, Fatemeh Karimi, Saied Karbalay-Doust, Ali Mohammad Kamali
Sleep Deprivation (SD) is known to result in a range of neurological consequences in chronically-afflicted subjects. Curcumin, a natural substance, has neuroprotective properties. This study aimed to evaluate the effects of curcumin on the medial Prefrontal Cortex (mPFC) of SD rats. Male rats were arbitrarily assigned to nine groups, including control, curcumin (100 mg/kg/day), olive oil, SD, SD+curcumin, SD+olive oil, grid, grid+curcumin, and grid+olive oil groups. SD was induced by a multiplatform box containing water...
2017: EXCLI journal
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