Noise Resilience of an RGNG-based Grid Cell Model

2016 ◽  
Author(s):  
Jochen Kerdels ◽  
Gabriele Peters
Keyword(s):  
Cell Model ◽  
Grid Cell ◽  
Noise Resilience

scholarly journals ARM-Cortex M3-Based Two-Wheel Robot for Assessing Grid Cell Model of Medial Entorhinal Cortex: Progress towards Building Robots with Biologically Inspired Navigation-Cognitive Maps

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
J. Cuneo ◽  
L. Barboni ◽  
N. Blanco ◽  
M. del Castillo ◽  
J. Quagliotti
Keyword(s):  
Embedded System ◽  
Entorhinal Cortex ◽  
Cell Model ◽  
Systems Design ◽  
Grid Cell ◽  
Network Models ◽  
Time Algorithm ◽  
Neural Network Models ◽  
Biologically Inspired ◽  
Medial Entorhinal Cortex

This article presents the implementation and use of a two-wheel autonomous robot and its effectiveness as a tool for studying the recently discovered use of grid cells as part of mammalian’s brains space-mapping circuitry (specifically the medial entorhinal cortex). A proposed discrete-time algorithm that emulates the medial entorhinal cortex is programed into the robot. The robot freely explores a limited laboratory area in the manner of a rat or mouse and reports information to a PC, thus enabling research without the use of live individuals. Position coordinate neural maps are achieved as mathematically predicted although for a reduced number of implemented neurons (i.e., 200 neurons). However, this type of computational embedded system (robot’s microcontroller) is found to be insufficient for simulating huge numbers of neurons in real time (as in the medial entorhinal cortex). It is considered that the results of this work provide an insight into achieving an enhanced embedded systems design for emulating and understanding mathematical neural network models to be used as biologically inspired navigation system for robots.

Bionic Multiscale Grid Cell Model for Robot Localization and Navigation

2021 ◽  
Author(s):  
Tao Geng ◽  
Bo Zhu ◽  
Xiaofei Sun ◽  
Jia Zhang
Keyword(s):  
Cell Model ◽  
Grid Cell ◽  
Robot Localization

scholarly journals Deforming the metric of cognitive maps distorts memory

2018 ◽  
Author(s):  
Jacob L. S. Bellmund ◽  
William de Cothi ◽  
Tom A. Ruiter ◽  
Matthias Nau ◽  
Caswell Barry ◽  
...  
Keyword(s):  
Spatial Memory ◽  
Cell Model ◽  
Cell Activity ◽  
Grid Cell ◽  
Cognitive Maps ◽  
Grid Cells ◽  
Boundary Geometry ◽  
Frequency Changes ◽  
Environmental Geometry ◽  
The Impact

AbstractEnvironmental boundaries anchor cognitive maps that support memory. However, trapezoidal boundary geometry distorts the regular firing patterns of entorhinal grid cells proposedly providing a metric for cognitive maps. Here, we test the impact of trapezoidal boundary geometry on human spatial memory using immersive virtual reality. Consistent with reduced regularity of grid patterns in rodents and a grid-cell model based on the eigenvectors of the successor representation, human positional memory was degraded in a trapezoid compared to a square environment; an effect particularly pronounced in the trapezoid’s narrow part. Congruent with spatial frequency changes of eigenvector grid patterns, distance estimates between remembered positions were persistently biased; revealing distorted memory maps that explained behavior better than the objective maps. Our findings demonstrate that environmental geometry affects human spatial memory similarly to rodent grid cell activity — thus strengthening the putative link between grid cells and behavior along with their cognitive functions beyond navigation.

scholarly journals Planning a high-frequency transfer-based bus network: How do we get there?

2021 ◽  
Vol 14 (1) ◽  
pp. 863-884
Author(s):  
Emily Grise ◽  
Anson Stewart ◽  
Ahmed El-Geneidy
Keyword(s):  
High Frequency ◽  
Urban Areas ◽  
Planning Process ◽  
Public Transit ◽  
Cell Model ◽  
Grid Cell ◽  
The United States ◽  
Performance Measure ◽  
Transit Ridership ◽  
Bus Network

As cities have grown more dispersed and auto-oriented, demand for travel has become increasingly difficult to meet via public transit. Public transit ridership, particularly bus ridership, has recently been on the decline in many urban areas in Canada and the United States, and many agencies have either undergone or are planning comprehensive bus network redesigns in response. While comprehensive bus network redesigns are not novel to public transit, network redesigns are commonly being considered in cities to optimize operational costs and reverse downward trends in transit ridership. For cities considering a comprehensive bus network redesign, there is currently no comprehensive easy-to-follow planning process available to guide cities through such a major undertaking. In light of that, this study presents a methodology to guide transport professionals through the planning process of a bus network redesign, using Longueuil, Quebec, as a case study. Currently, Longueuil operates a door-to-door network, and the goal is to move to a transfer-based, high-frequency service while keeping the existing number of buses constant. A variety of data sources that capture regional travel behavior and network performance are overlaid using a GIS-based grid-cell model to identify priority bus corridors. A series of analyses to measure and quantify anticipated and actual improvements from the proposed bus network redesign are conducted, including coverage analysis, change in accessibility to jobs, and travel time analysis. Accessibility to jobs was the key performance measure used in this analysis and is presented as a useful tool for planners and transit agencies to obtain buy-in for the proposed plan. This methodology provides transport professionals with a flexible and reproducible guide to consider when conducting a bus network redesign, while ensuring that such a network overhaul maximizes the number of opportunities that residents can access by transit and does not add an additional burden to an agency’s operating budget.

scholarly journals AutonomousWalking over Obstacles by Means of LRF for Hexapod Robot COMET-IV

2012 ◽  
Vol 24 (1) ◽  
pp. 55-63 ◽  
Author(s):  
Mohd Razali Daud ◽  
◽  
Kenzo Nonami ◽  
Keyword(s):  
Autonomous Navigation ◽  
Point Cloud ◽  
Cell Model ◽  
Search Algorithm ◽  
Grid Cell ◽  
Point Cloud Data ◽  
Hexapod Robot ◽  
Cloud Data ◽  
Grid Based

This paper presents an autonomous navigation system for a hydraulically driven hexapod robot (COMETIV) based on point cloud data acquired using a rotating Laser Range Finder (LRF). The size of the robot would prohibit its movement in a stochastic terrain environment if we only consider letting it avoid obstacles. However, the robot has a unique ability to walk over obstacles. We thus proposed the so-called Grid-based Walking Trajectory for Legged Robot (GWTLR) method. The method is developed on the basis of the geometric representation of a stochastic terrain in terms of grid cell characteristics. We also introduced the “Grid-cell model for COMET-IV” to assess the characteristics of the grid cells and to determine whether each of the cells is traversable or not. Finally, the shortest safe walking trajectory is generated using a search algorithm, A*. The performance of the proposed method is verified by the experimental results of the successful determination of a walking trajectory path and by completely walking over obstacles in various arrangements.

Endogenous hydrogen sulfide sulfhydrates IKKβ at cysteine 179 to control pulmonary artery endothelial cell inflammation

2019 ◽  
Vol 133 (20) ◽  
pp. 2045-2059 ◽  
Author(s):  
Da Zhang ◽  
Xiuli Wang ◽  
Siyao Chen ◽  
Selena Chen ◽  
Wen Yu ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Endothelial Cell ◽  
Pulmonary Artery ◽  
Cell Model ◽  
Site Directed Mutagenesis ◽  
Critical Event ◽  
Hypertensive Rats ◽  
Pulmonary Artery Endothelial Cell

Abstract Background: Pulmonary artery endothelial cell (PAEC) inflammation is a critical event in the development of pulmonary arterial hypertension (PAH). However, the pathogenesis of PAEC inflammation remains unclear. Methods: Purified recombinant human inhibitor of κB kinase subunit β (IKKβ) protein, human PAECs and monocrotaline-induced pulmonary hypertensive rats were employed in the study. Site-directed mutagenesis, gene knockdown or overexpression were conducted to manipulate the expression or activity of a target protein. Results: We showed that hydrogen sulfide (H2S) inhibited IKKβ activation in the cell model of human PAEC inflammation induced by monocrotaline pyrrole-stimulation or knockdown of cystathionine γ-lyase (CSE), an H2S generating enzyme. Mechanistically, H2S was proved to inhibit IKKβ activity directly via sulfhydrating IKKβ at cysteinyl residue 179 (C179) in purified recombinant IKKβ protein in vitro, whereas thiol reductant dithiothreitol (DTT) reversed H2S-induced IKKβ inactivation. Furthermore, to demonstrate the significance of IKKβ sulfhydration by H2S in the development of PAEC inflammation, we mutated C179 to serine (C179S) in IKKβ. In purified IKKβ protein, C179S mutation of IKKβ abolished H2S-induced IKKβ sulfhydration and the subsequent IKKβ inactivation. In human PAECs, C179S mutation of IKKβ blocked H2S-inhibited IKKβ activation and PAEC inflammatory response. In pulmonary hypertensive rats, C179S mutation of IKKβ abolished the inhibitory effect of H2S on IKKβ activation and pulmonary vascular inflammation and remodeling. Conclusion: Collectively, our in vivo and in vitro findings demonstrated, for the first time, that endogenous H2S directly inactivated IKKβ via sulfhydrating IKKβ at Cys179 to inhibit nuclear factor-κB (NF-κB) pathway activation and thereby control PAEC inflammation in PAH.

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