Amount Of Spatial Information Research Articles

Distal CA1 Maintains a More Coherent Spatial Representation than Proximal CA1 When Local and Global Cues Conflict.

Entorhinal cortical projections show segregation along the transverse axis of CA1, with the medial entorhinal cortex (MEC) sending denser projections to proximal CA1 (pCA1) and the lateral entorhinal cortex (LEC) sending denser projections to distal CA1 (dCA1). Previous studies have reported functional segregation along the transverse axis of CA1 correlated with the functional differences in MEC and LEC. pCA1 shows higher spatial selectivity than dCA1 in these studies. We employ a double rotation protocol, which creates an explicit conflict between the local and the global cues, to understand the differential contributions of these reference frames to the spatial code in pCA1 and dCA1 in male Long-Evans rats. We show that pCA1 and dCA1 respond differently to this local-global cue conflict. pCA1 representation splits as predicted from the strong conflicting inputs it receives from MEC and dCA3. In contrast, dCA1 rotates more in concert with the global cues. In addition, pCA1 and dCA1 display comparable levels of spatial selectivity in this study. This finding differs from the previous studies, perhaps because of richer sensory information available in our behavior arena. Together, these observations indicate that the functional segregation along proximodistal axis of CA1 is not of the amount of spatial selectivity but that of the nature of the different inputs used to create and anchor spatial representations.SIGNIFICANCE STATEMENT Subregions of the hippocampus are thought to play different roles in spatial navigation and episodic memory. It was previously thought that the distal part of area CA1 of the hippocampus carries lesser information about space than proximal CA1 (pCA1). We report that distal CA1 (dCA1) spatial representation moves more in concert with the global cues than pCA1 when the local and the global cues conflict. We also show that spatial selectivity is comparable along the proximodistal axis in this experimental protocol. Thus, different parts of the brain receiving differential outputs from pCA1 and dCA1 receive spatial information in different spatial reference frames encoded using different sets of inputs, rather than different amounts of spatial information as thought earlier.

Shedding light on the prefrontal correlates of mental workload in simulated driving: a functional near-infrared spectroscopy study

Optimal mental workload plays a key role in driving performance. Thus, driver-assisting systems that automatically adapt to a drivers current mental workload via brain–computer interfacing might greatly contribute to traffic safety. To design economic brain computer interfaces that do not compromise driver comfort, it is necessary to identify brain areas that are most sensitive to mental workload changes. In this study, we used functional near-infrared spectroscopy and subjective ratings to measure mental workload in two virtual driving environments with distinct demands. We found that demanding city environments induced both higher subjective workload ratings as well as higher bilateral middle frontal gyrus activation than less demanding country environments. A further analysis with higher spatial resolution revealed a center of activation in the right anterior dorsolateral prefrontal cortex. The area is highly involved in spatial working memory processing. Thus, a main component of drivers’ mental workload in complex surroundings might stem from the fact that large amounts of spatial information about the course of the road as well as other road users has to constantly be upheld, processed and updated. We propose that the right middle frontal gyrus might be a suitable region for the application of powerful small-area brain computer interfaces.

Análisis espacio temporal (1981-2010) de la precipitación en la ciudad de Bogotá: avances en la generación de índices extremos

La investigación analizó los escenarios espaciales y temporales de eventos extremos de precipitación en Bogotá, Colombia, a partir del desarrollo de los índices de extremos climáticos avalados por el Panel Intergubernamental del Cambio Climático (IPCC) y por su capacidad de predicción de tendencias climáticas. Se trabajaron datos de frecuencia diaria y registros de treinta años de 23 estaciones meteorológicas distribuidas ampliamente en la ciudad, con el fin de brindar la mayor cantidad de información espacial. Se controló la calidad y ausencia de datos. El perfil climatológico reveló dos regímenes pluviométricos mensuales en el área de estudio con valores de hasta 87.2 mm/día de precipitación, además se encontraron dos amplias zonas de convergencia de precipitación. Los índices evidenciaron una tendencia positiva regional salvo en el sur de la ciudad que se presentaron tendencias negativas, lo que proyectó notables cambios en la intensidad, duración y frecuencia de eventos extremos, de igual manera el análisis geoestadístico detalló la zona oriental con un amplio matiz en la dinámica hidrológica, apropiada para explorarse en futuras investigaciones. En última instancia, esta investigación se orienta en ampliar y divulgar información clave en la planeación y ordenación del territorio, así como también en la prevención y gestión del riesgo frente a escenarios de extremos climáticos como deslizamientos de tierra, inundaciones o sequias en ciudades situadas por encima de los 2000 m.s.n.m. y de esta manera ayudar a tomadores de decisiones, investigadores, profesores y estudiantes universitarios en emplear una metodología aprobada internacionalmente que unifica criterios para el cotejo de información climática.

Development of GIS Interface Tool for GAMES Model and Its Application to an Agricultural Watershed in Southern Ontario

Soil erosion is an important economic and environmental concern throughout the world. In order to assess soil erosion risk and conserve soil and water resources, soil erosion modeling at the watershed scale is imperative. The Guelph model for evaluating effects of Agricultural Management System on Erosion and Sedimentation (GAMES) is tailor-made for such applications; it, however, requires a significant amount of spatial information which needs to be pre-processed using a Geographic Information System (GIS). The GAMES model currently lacks any such automated tools. As such, the GAMES was loosely coupled to a GIS interface to manage the large spatial input data and to produce efficient cartographic representations of model output results. The developed interface tool was tested to simulate the Kettle Creek paired watershed in Southern Ontario, Canada. Result demonstrated that the GIS-assisted procedure increased the ability of the GAMES model in simulating such a spatially varied watershed and made the process more efficient and user-friendly. Furthermore, the quality of reporting and displaying resultant spatial output was also significantly improved. The developed GAMES interface could be applied to any watershed, and the enhancement could be used to assess soil erosion risk and conserve soil and water resources in an effective way.

Adaptive time-variant adjustment for the positioning errors of a mobile mapping platform in GNSS-hostile areas

A mobile mapping system (MMS) utilizes global navigation satellite system (GNSS) and inertial navigation system (INS) techniques and thus makes possible a direct geo-referencing solution everywhere along its surveyed path. It is capable of acquiring a vast amount of spatial information in an efficient manner and is adopted in a wide variety of applications. However, when the GNSS signal is obstructed, its positioning solution can only rely on the INS observables, which acquire significant and cumulative errors over time. In this study, an adaptive time-variant adjustment model is proposed to compensate for the MMS positioning error in a GNSS-hostile area using ground calibration points. Based on the results from a case study, it illustrates that the positioning error of a mobile mapping platform in an urban area for a long time could reach a level of several metres because of GNSS signal obstructions. However, this error can be properly modelled and significantly reduced to a centimetre-level when the proposed approach is applied. Consequently, both the efficiency and reliability of the MMS applications in a GNSS hostile environment can be further guaranteed.

Maps of fire occurrence – spatially explicit reconstruction of recent fire history using satellite remote sensing

Maps depicting the spatially explicit fire history of an area, including variables such as fire frequency and fire return interval, are important tools promoting the understanding of processes associated with wildfires (fire ignition and spread), the assessment of the impacts of wildland fires on landscape dynamics, and decisions on appropriate management practices. Remote sensing is a cost- and time-effective alternative to automatically assess a vast amount of spatial information and produce various thematic maps. The aim of this study was to reconstruct the recent fire history of Attica region (Greece), in a spatially explicit mode by means of remote sensing techniques using a series of Landsat images acquired from 1984 to 2011. The results show that the fire scar perimeters were captured with high accuracy. Regression modelling shows that the differences between the area burned estimated from satellite data and that recorded by the forest service can be explained (86.3% of the variance) by the number of satellite images used (standardized coefficient 0.752) followed by the date of the first image (standardized coefficient 0.705). The use of satellite data as the basic source of information alongside automated classification methods should be promoted for the creation of fire history maps. The latter is further supported when considering the long history of data capture from Landsat satellites, which provide a huge, global historical archive of repeat images of the Earth's surface.

A Spatially Autocorrelated Weights of Evidence Model

One of the most important features of spatial datasets is that they often exhibit spatial autocorrelation, where locational similarities are observed jointly with similarities in values. Both logistic regression (LR) modelling and weights of evidence (WE) modelling are methods commonly applied in binary pattern recognition. While a spatially autocorrelated variant of the LR model, the so-called autologistic regression (ALR) model, exists in the literature, a spatially autocorrelated variant of the WE model does not exist. In this paper, a spatially autocorrelated weights of evidence (SACWE) model will be proposed. It will be demonstrated that the new model contains the same amount of spatial information as does an ALR model, and it is easy to program and implement. Via a simulation study, it will be shown that, in the presence of spatial autocorrelation, both in terms of in-sample fit and out-of-sample predictions the SACWE model is on par with the ALR model, while significantly outperforming the conventional WE model.

Stability of Hippocampal Place Cells Activity After Peripheral Nerve Injury: A Study Based on Chronic Extracellular Multichannel Recordings

Event Abstract Back to Event Stability of Hippocampal Place Cells Activity After Peripheral Nerve Injury: A Study Based on Chronic Extracellular Multichannel Recordings Helder Cardoso-Cruz1, 2*, Deolinda Lima1, 3 and Vasco Galhardo1, 2 1 Universidade do Porto, Instituto de Biologia Molecular e Celular (IBMC), Unidade de Morfofisiologia do Sistema Somato-sensitivo, Portugal 2 Faculdade de Medicina, Universidade do Porto, Instituto de Histologia e Embriologia, Portugal 3 Faculdade de Medicina, Universidade do Porto, Laboratorio de Biologia Celular, Portugal The hippocampus is important for processing the spatial layout and configural representation of an environment. In addition, it has been shown that the rat hippocampal CA1 pyramidal complex-spike “place” cells respond to persistent noxious activation. The aim of the present study was to evaluate the effects of a peripheral neuropathic pain condition on the properties of spatial CA1 hippocampal place cells. Our results include extracelluar single-unit data from 6 adult male Sprague-Dawley rats trained to alternate on a U- shaped runway for food reinforcement. A total of 54 place cells were recorded from CA1 in 4 SNI (n=36) and 2 SHAM (n=18) animals. Spatial firing and place field characteristics of the cells were examined before (10 days) and after (21 days) peripheral nerve injury (SNI). The findings showed an increase of the number of place fields encoded per cell and an increase of the place field size (expansion) after nerve injury. In addition, the infield coherence increases for the SNI-group and amount of spatial information (specificity) content that a single spike conveyed about the animal location decrease over time. However, other measures of spatial tuning (e. g. infield firing rate, firing peak and number of spikes) were unchanged between the two experimental groups. The current study suggests that there is a relative instability of hippocampal place cells across the installation of the peripheral pain condition in a well-trained task.Supported by FCT Grant- SFRH/BD/42500/2007 and BIAL Project-126/08. Conference: 11th Meeting of the Portuguese Society for Neuroscience, Braga, Portugal, 4 Jun - 6 Jun, 2009. Presentation Type: Poster Presentation Citation: Cardoso-Cruz H, Lima D and Galhardo V (2009). Stability of Hippocampal Place Cells Activity After Peripheral Nerve Injury: A Study Based on Chronic Extracellular Multichannel Recordings. Front. Neurosci. Conference Abstract: 11th Meeting of the Portuguese Society for Neuroscience. doi: 10.3389/conf.neuro.01.2009.11.058 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 07 Aug 2009; Published Online: 07 Aug 2009. * Correspondence: Helder Cardoso-Cruz, Universidade do Porto, Instituto de Biologia Molecular e Celular (IBMC), Unidade de Morfofisiologia do Sistema Somato-sensitivo, Porto, Portugal, hcruz@ibmc.up.pt Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Helder Cardoso-Cruz Deolinda Lima Vasco Galhardo Google Helder Cardoso-Cruz Deolinda Lima Vasco Galhardo Google Scholar Helder Cardoso-Cruz Deolinda Lima Vasco Galhardo PubMed Helder Cardoso-Cruz Deolinda Lima Vasco Galhardo Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Joint spectral and spatial quality evaluation of pan-sharpening algorithms

This research study presents a novel global index based on harmonic mean theory to jointly evaluate the performance of pan-sharpening algorithms without using a reference image. The harmonic mean of relative spatial information gain and relative spectral information preservation provides a unique global index to compare the performance of different methods. The presented index also facilitates in assigning relevance to either the spectral or spatial quality of an image. The information divergence between the multispectral (MS) bands at lower resolutions and the pan-sharpened image provides a measure of the spectral fidelity and mean-shift. Mutual information between the original pan and the synthetic pan images generated from the MS and pan-sharpened images is used to calculate the relative gain. The relative gain helps to quantify the amount of spatial information injected by the method. A trend comparison of the presented approach with other quality indices using well-known pan-sharpening methods on high resolution and medium resolution datasets reveals that the new index can be used to evaluate the quality of pan-sharpened images at the resolution of the pan image without the availability of a reference image.

Enhancement of Infrared Spectral Images for Maximizing Chemical Information by Minimizing Baseline Interferences

The popularity of spectral images in many areas of analysis has greatly increased during the last decade due to the development of charge-coupled device (CCD) and infrared sensitive cameras. Large amounts of spatial information can be obtained in short periods of time. The general goal in analytical chemistry is to convert spectral images into chemical images, which show the spatial locations of various chemical components. Self-modeling multivariate curve resolution methods can be used to extract pure component spectra from the mixture spectra in images and produce chemical images. However, there is a difficulty in processing infrared spectral images due to large pixel-to-pixel baseline variations. Herein, a method for minimizing baseline interferences using fast Fourier transform (FFT) filtering in both the spectral and spatial domains is discussed. The methodology is demonstrated on a microscopic sample of butter contaminated with non-pathogenic E. coli and on a cross-sectional sample of rabbit aorta containing plaque. The processing to reduce baseline effects improved the spatial resolution without compromising the spectral resolution.

Temporal–spatial memory: retrieval of spatial information does not reduce recency

Factors influencing the shape of serial position curves in non-verbal serial short-term memory were examined, using a task testing memory for the position of dots. Similar recency slopes were found when both position and order were recalled (Experiment 1A) and when order only was required (Experiment 1B). This observation was confirmed and tested further in conditions requiring the same encoding but different amounts of spatial information at retrieval (Experiment 2). However, Experiment 2 also revealed an effect of spatial information retrieval on the overall level of memory for recency items. Overall, the results indicate that spatial items produce bow-shaped serial positions curves in tasks requiring the maintenance of order information and that recency is affected by the demand on spatial information retrieval in terms of the overall level of performance but not in terms of the recency slope. These findings are contrary to what is found in the literature on serial verbal recall when both item and order information are required.

Guest Editorial: Geocomputation and GIS

As computers become faster and more powerful, it is increasingly possible to provide better solutions to many geographical problems by developing new, computationally dependent tools for analysis and modelling. The term ‘geocomputation’ has been coined to describe the development and application of these tools. There are already indications of a significant increase in the number of research activities and funding opportunities that involve leading-edge computer-based tools and techniques, and geocomputational techniques are poised to provide novel solutions to a mix of old and new problems in spatial analysis. An increasingly important component of much geocomputational analysis is the use of GIs. These provide the platform for data storage, abstraction, analysis, and visualization. However, although GIS have successfully created an infrastructure for gathering, storing, and manipulating spatial information, these technologies are often deficient when it come to analysis and modelling. Geography needs to use, process, and add value to the massive amount of spatial information now available and researchers in GIS are well-poised to exploit the impact of new technologies for performing these tasks. The leading parallel supercomputers are today running at speeds a few thousand times faster than those provided by even the fastest personal computers and offer memory spaces soon expected to reach a Terabyte. The papers in this special issue of Tranructions in GZS demonstrate the link between computational power and GIs. They were presented at the First International Conference on Geocomputation held at the University of Leeds in 1996. The principal objective of the conference was to bring together various emergent, computer-oriented activities for the analysis and modelling of spatial data. The paper by Brookes, for example, examines the problem of identifying optimal locations of facilities on raster maps when the facilities are larger than the cell size used in the raster. A genetic algorithm is described which searches for optimal or near-optimal clusters of cells and then employs a raster GIS to evaluate the utility scores for these clusters. The results suggest that the genetic algorithm can find good solutions to locational problems when exhaustive search methods are impractical. Park and Wagner investigate a coupling of cellular automata and GIS in which the cellular automata act as an analytical engine for the GIs. Examples given on spatial diffusion and spatiotemporal processes show how dynamic spatial modelling can be handled within a GIs. Lilburne et al address the interesting issue of interoperability and GIs. As we demand more and more of GIs, particularly in the arena of spatial analysis, the question of where to draw the balance between one all-embracing GIS and the establishment of an increasing number of flexible interfaces to other systems arises. Interoperability is an attempt to recognize that some middle ground might provide the optimal future for GIs. In two very different papers, Takeyama describes his vision of Geo-Algebra to facilitate geocomputational modelling within a GIS while

A Century of Forest Management Mapping

Large scale, detailed maps have been produced and maintained by forestry agencies in many parts of central Europe since the mid nineteenth century. This paper describes a series of maps supporting the management of a forest area in Austria from 1872 until 1996. The last edition of this series marks the end of an era of forest mapping based on traditional to surveying and manual cartography. The historical development of this map series is examined in terms of the type and amount of spatial information. It was found that the locational accuracy of the various maps does not significantly vary. Historical forest maps provide a record of past management practice and may therefore be usefully incorporated into spatial information systems to support current management. Several approaches to converting the forest maps of various dates to digital form were tested and found to give some improvement in metric quality. The remaining relative locational disagreements hamper the incorporation of these historical data in a GIS database.

A Century of Forest Management Mapping

Large scale, detailed maps have been produced and maintained by forestry agencies in many parts of central Europe since the mid nineteenth century. This paper describes a series of maps supporting the management of a forest area in Austria from 1872 until 1996. The last edition of this series marks the end of an era of forest mapping based on traditional to surveying and manual cartography. The historical development of this map series is examined in terms of the type and amount of spatial information. It was found that the locational accuracy of the various maps does not significantly vary. Historical forest maps provide a record of past management practice and may therefore be usefully incorporated into spatial information systems to support current management. Several approaches to converting the forest maps of various dates to digital form were tested and found to give some improvement in metric quality. The remaining relative locational disagreements hamper the incorporation of these historical data in a GIS database.

Young children's ability to detect ambiguity in descriptions of location

Three experiments investigated 3- to 5-year-olds' ability to detect ambiguity in descriptions of location. In Experiments 1 and 2, children received ambiguous (e.g., “it's in one of the bags”) and nonambiguous (e.g., “it's in the bag by the chair”) descriptions. Four- and 5-year-olds' search latencies were longer for ambiguous than for nonambiguous descriptions, but 3-year-olds' latencies were longer for nonambiguous than for ambiguous descriptions. Experiment 3 revealed no difference in 3-year-olds' search latencies for ambiguous and nonambiguous descriptions when amount of spatial information in directions was equated. Five-year-olds' latencies again were longer for ambiguous than for nonambiguous descriptions. Discussion focuses on possible developmental factors contributing to changes in children's ability to detect spatial ambiguity.

Classifying graphical information

Abstract The research lays the groundwork for a taxonomy of visual representations by establishing a methodology for determining the kinds of knowledge conveyed by different graphical representations. In the first of two experiments, the basic categories and dimensions of a set of graphics were established using a sorting procedure. Five principal categories emerged: graphs/tables, maps, diagrams, networks, and icons. Furthermore, two principal dimensions characterize these groups: amount of spatial information and amount of cognitive processing effort. The second experiment validated and extended this understanding of the cognitive structure of visual representations. In that experiment, similarity among items was assessed using pairwise similarity judgements. The results confirmed the original categories and revealed distinct differences between subjects who did or did not have graphic arts training.