scholarly journals Multi-Transition Systems: A theory for neural spatial navigation

2017 ◽  
Author(s):  
Nicolai Waniek
Keyword(s):  
Multiple Scales ◽  
Spatial Navigation ◽  
Formal Theory ◽  
Scale Space ◽  
Sampling Theorem ◽  
Grid Cells ◽  
Look Ahead ◽  
Dendritic Computation ◽  
Single Scale ◽  
Plausible Model

AbstractSpatial navigation is considered fundamental for animals and is attributed primarily to place and grid cells in the rodent brain. Commonly believed to either perform path integration or localization, the true objective of grid cells, their hexagonal grid fields, and especially their discrete scales remain puzzling. Here it is proposed that grid cells efficiently encode transitions in sequences. A biologically plausible model for dendritic computation in grid cells is presented. A network of competitive cells shows positive gridness scores early in simulations and realigns the orientation of all cells over time. Then, a scale-space model of grid cells is introduced. It improves behaviorally questionable run-times of a single scale significantly by look-ahead in multiple scales, and it is shown that the optimal scale-increment between consecutive scales is √2. Finally, a formal theory for sequences and transitions is stated. It is demonstrated that hexagonal transition encoders are optimal to encode transitions in Euclidean space and emerge due to the sampling theorem. The paper concludes with a discussion about the suggested purpose, makes testable predictions, and highlights relevant connections to computational neuroscience as well as computer science and robotics.

Spatial Causality in Bilateral Symmetry Detection

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 181-181
Author(s):  
J Hulleman ◽  
A H J Oomes
Keyword(s):  
Spatial Scale ◽  
Multiple Scales ◽  
Reaction Times ◽  
Bilateral Symmetry ◽  
Scale Space ◽  
Causality Principle ◽  
Circular Aperture ◽  
Fine Scale ◽  
Black And White ◽  
Random Patterns

We studied the influence of spatial scale on the detection of vertical and horizontal bilateral symmetry. The causality principle in scale - space theory states that increasing the spatial scale in a representation can only result in a decrease of structure. Consequently, a pattern can be random on the fine scale and symmetric on the coarse scale, never the reverse. Stimuli were bilaterally symmetric or random patterns, black-and-white on a grey background, with a circular aperture. The minimal scale was systematically varied and stimuli ranged from conventional noise patterns, through Dalmatian texture, to cow-like patterns. Observers had to judge whether a briefly presented pattern was ‘symmetric’ or ‘random’. Symmetric patterns resulted in a high accuracy (95%) with no influence of scale, and reaction times with a small linear decrease for increasing scale. Random patterns yielded an accuracy increasing from 70% at the smallest scale to 95% at the middle scales. Reaction times showed a similar pattern: largest at the smallest scales and decreasing to values equal to the symmetric condition at the middle scales. Results were similar for vertical and horizontal bilateral symmetry, though the effect for small scales in the random condition was more pronounced in the horizontal case. We conclude that bilateral symmetry is processed at multiple scales with coarse structures available slightly earlier than fine ones. The dramatic decrease of performance for fine-scale patterns is due to the causality effect; random patterns are judged as symmetric when the smallest scale information is not (yet) available.

scholarly journals Intelligent Fault Diagnosis of Rotating Machinery Using Hierarchical Lempel-Ziv Complexity

2020 ◽  
Vol 10 (12) ◽  
pp. 4221 ◽  
Author(s):  
Bing Han ◽  
Shun Wang ◽  
Qingqi Zhu ◽  
Xiaohui Yang ◽  
Yongbo Li
Keyword(s):  
Fault Diagnosis ◽  
Multiple Scales ◽  
Complexity Analysis ◽  
Low Frequency ◽  
Health Condition ◽  
Rotating Machinery ◽  
Vibrational Signal ◽  
Single Scale ◽  
Frequency Components ◽  
Fault Information

The health condition monitoring of rotating machinery can avoid the disastrous failure and guarantee the safe operation. The vibration-based fault diagnosis shows the most attractive character for fault diagnosis of rotating machinery (FDRM). Recently, Lempel-Ziv complexity (LZC) has been investigated as an effective tool for FDRM. However, the LZC only performs single-scale analysis, which is not suitable to extract the fault features embedded in vibrational signal over multiple scales. In this paper, a novel complexity analysis algorithm, called hierarchical Lempel-Ziv complexity (HLZC), was developed to extract the fault characteristics of rotating machinery. The proposed HLZC method considers the fault information hidden in both low-frequency and high-frequency components, resulting in a more accurate fault feature extraction. The superiority of the proposed HLZC method in detecting the periodical impulses was validated by using simulated signals. Meanwhile, two experimental signals were utilized to prove the effectiveness of the proposed HLZC method in extracting fault information. Results show that the proposed HLZC method had the best diagnosing performance compared with LZC and multi-scale Lempel-Ziv complexity methods.

How Does Collaborative Governance Scale?

2018 ◽  
Keyword(s):  
Multiple Scales ◽  
Collaborative Governance ◽  
Employment Policy ◽  
Humanitarian Relief ◽  
Single Scale ◽  
Wide Range ◽  
North And South America ◽  
North And South

Scale is an overlooked issue in the research on interactive governance. This book takes up the important task of investigating the scalar dimensions of collaborative governance in networks, partnerships, and other interactive arenas and explores the challenges of operating at a single scale, across or at multiple scales and of moving between scales. The introductory chapter presents a general framework for thinking about the scale of collaborative governance and for conceptualizing dynamic processes of scaling. These general ideas provide the basis for examining the role of scale and scaling in a wide range of policy areas, including employment policy, water management, transportation planning, public health, university governance, artistic markets, child welfare and humanitarian relief. Cases are drawn from Asia, Australia, Europe, and North and South America and span all levels from local to global. Together, the theoretical framework and the empirical case studies sensitize us to the tensions that arise between scales of governance and to the challenges of shifting from one scale of governance to another.

scholarly journals MSICA: multi-scale signal decomposition based on independent component analysis with application to denoising and reliable multi-channel

2020 ◽  
Vol 1 (1) ◽  
pp. 25-35
Author(s):  
Abolfazl Hajisami ◽  
Dario Pompili
Keyword(s):  
Independent Component Analysis ◽  
Multiple Scales ◽  
Digital Signal ◽  
Component Analysis ◽  
Scale Space ◽  
Independent Component ◽  
Signal Denoising ◽  
Multi Scale ◽  
Information Preservation ◽  
Bank Structure

Multi-scale decomposition is a signal description method in which the signal is decomposed into multiple scales, which has been shown to be a valuable method in information preservation. Much focus on multi-scale decomposition has been based on scale-space theory and wavelet transform. In this article, a new powerful method to perform multi-scale decomposition exploiting Independent Component Analysis (ICA), called MSICA, is proposed to translate an original signal into multiple statistically independent scales. It is proven that extracting the independent components of the even and odd samples of a digital signal results in the decomposition of the same into approximation and detail. It is also proven that the whitening procedure in ICA is equivalent to a filter bank structure. Performance results of MSICA in signal denoising are presented; also, the statistical independency of the approximation and detail is exploited to propose a novel signal-denoising strategy for multi-channel noisy transmissions aimed at improving communication reliability by exploiting channel diversity.

scholarly journals Local microcircuitry of parasubiculum shows distinct and common features of excitatory and inhibitory connectivity

2020 ◽  
Author(s):  
Rosanna P Sammons ◽  
Alexandra Tzilivaki ◽  
Dietmar Schmitz
Keyword(s):  
Random Network ◽  
Spatial Navigation ◽  
Border Cells ◽  
Head Direction ◽  
Grid Cells ◽  
Medial Entorhinal Cortex ◽  
Common Features ◽  
Layer 2 ◽  
Firing Properties ◽  
Local Circuitry

The parasubiculum is located within the parahippocampal region, where it is thought to be involved in the processing of spatial navigational information. It contains a number of functionally specialised neuron types including grid cells, head direction cells and border cells, and provides input into layer 2 of the medial entorhinal cortex where grid cells are abundantly located. The local circuitry within the parasubiculum remains so far undefined but may provide clues as to the emergence of spatially tuned firing properties of neurons in this region. We used simultaneous patch-clamp recordings to determine the connectivity rates between the three major groups of neurons found in the parasubiculum. We find high rates of interconnectivity between the pyramidal class and interneurons, as well as features of pyramid to pyramid interactions indicative of a non-random network. The microcircuit that we uncover shares both similarities and divergences to those from other parahippocampal regions also involved in spatial navigation.

scholarly journals Effects of Scale on Multimodal Deixis: Evidence From Quiahije Chatino

2021 ◽  
Vol 11 ◽  
Author(s):  
Kate Mesh ◽  
Emiliana Cruz ◽  
Joost van de Weijer ◽  
Niclas Burenhult ◽  
Marianne Gullberg
Keyword(s):  
Large Scale ◽  
Multiple Scales ◽  
Search Space ◽  
Scale Space ◽  
Hand Movements ◽  
Indigenous Language ◽  
San Juan ◽  
Dynamic Nature ◽  
Local Activity ◽  
The World

As humans interact in the world, they often orient one another's attention to objects through the use of spoken demonstrative expressions and head and/or hand movements to point to the objects. Although indicating behaviors have frequently been studied in lab settings, we know surprisingly little about how demonstratives and pointing are used to coordinate attention in large-scale space and in natural contexts. This study investigates how speakers of Quiahije Chatino, an indigenous language of Mexico, use demonstratives and pointing to give directions to named places in large-scale space across multiple scales (local activity, district, state). The results show that the use and coordination of demonstratives and pointing change as the scale of search space for the target grows. At larger scales, demonstratives and pointing are more likely to occur together, and the two signals appear to manage different aspects of the search for the target: demonstratives orient attention primarily to the gesturing body, while pointing provides cues for narrowing the search space. These findings underscore the distinct contributions of speech and gesture to the linguistic composite, while illustrating the dynamic nature of their interplay.Abstracts in Spanish and Quiahije Chatino are provided as appendices.Se incluyen como apéndices resúmenes en español y en el chatino de San Juan Quiahije. SonG ktyiC reC inH, ngyaqC skaE ktyiC noE ndaH sonB naF ngaJ noI ngyaqC loE ktyiC reC, ngyaqC ranF chaqE xlyaK qoE chaqF jnyaJ noA ndywiqA renqA KchinA KyqyaC.

Fundamental Aspects Of Incompressible And Compressible Turbulent Flows

1996 ◽  
Author(s):  
John L. Lumley ◽  
Gal Berkooz
Keyword(s):  
Boundary Layer ◽  
Strain Rate ◽  
Turbulent Flows ◽  
Turbulence Modeling ◽  
Multiple Scales ◽  
Initial Boundary ◽  
Length Scales ◽  
Boundary Layer Turbulence ◽  
Single Scale ◽  
Velocity Turbulence

Turbulence generally can be characterized by a number of length scales: at least one for the energy containing range, and one from the dissipative range; there may be others, but they can be expressed in terms of these. Whether a turbulence is simple or not depends on how many scales are necessary to describe the energy containing range. Certainly, if a turbulence involves more than one production mechanism (such as shear and buoyancy, for example, or shear and density differences in a centripetal field) there will be more than one length scale. Even if there is only one physical mechanism, say shear, a turbulence which was produced under one set of circumstances may be subjected to another set of circumstances. For example, a turbulence may be produced in a boundary layer, which is then subjected to a strain rate. For a while, such turbulence will have two length scales, one corresponding to the initial boundary layer turbulence, and the other associated with the strain rate to which the flow is subjected. Or, a turbulence may have different length scales in different directions. Ordinary turbulence modeling is restricted to situations that can be approximated as having a single scale of length and velocity. Turbulence with multiple scales is much more complicated to predict. Some progress can be made by applying rapid distortion theory, or one or another kind of stability theory, to the initial turbulence, and predicting the kinds of structures that are induced by the applied distortion. We will talk more about this later. For now, we will restrict ourselves to a turbulence that has a single scale of length in the energy containing range.

The Hippocampus

2020 ◽  
pp. 166-179
Author(s):  
Frederick L. Coolidge
Keyword(s):  
Spatial Navigation ◽  
Place Cells ◽  
Grid Cells ◽  
Stable Maps ◽  
Olfactory Bulbs ◽  
Additional Stimulation

All mammals have a well-developed hippocampus compared to that of fish, reptiles, and birds, although the latter still have homologous structures. The cells of the hippocampus have differentiated roles: place cells become active and rearrange themselves in new environments, which create new and stable maps of those environments. Grid cells are able to approximate distances, forming an additional neuronal basis for spatial navigation. The hippocampus and olfactory bulbs have intimately related functions. The story of patient H.M. revealed that declarative memories are consolidated by the hippocampus, but procedural memories can be established without hippocampal involvement. Declarative memories remain vulnerable to disruption and forgetting up to about 3 years after memorization. Memories consolidated during sleep are less prone to interference and more stable than memories followed by additional stimulation or learning.

Issues in specifying contrast in building elements for people with a visual disability

Work ◽  
2021 ◽  
pp. 1-9
Author(s):  
Stephen John Dain ◽  
Catherine Bridge ◽  
Mark Relf ◽  
Aldyfra Luhulima Lukman ◽  
Sarita Manandhar ◽  
...  
Keyword(s):  
Gold Standard ◽  
Multiple Scales ◽  
The Other ◽  
Measurement Scale ◽  
Measurement Scales ◽  
Visual Disability ◽  
Single Scale ◽  
Contrast Measure ◽  
System Objective ◽  
Building Elements

BACKGROUND: Standards writers, national and international, have used different contrast calculations to set requirements in building elements for people with visual impairments. On the other hand, they have typically set a single requirement (30%) for specifying the minimum contrast. The systems are not linearly related and 30%means something rather different in each system. OBJECTIVE: To provide a comparison of the various scales in order to illustrate the differences caused by multiple scales with a single compliance value, recommend a single scale for universal adoption and, if a new measure is problematic for implementation, to recommend the most perceptually uniform of the present methods. METHODS: We use the contrast between combinations of 205 paint colours to illustrate the relationships between the measures. We use an internationally accepted scale, with equal perceptual steps, as a “gold standard” to identify the most perceptually uniform measurement scale in the existing methods. RESULTS: We show that Michelson contrast is the most perceptually uniform of the existing measurement scales. We show the contrasts in the proposed method that equate to the various current requirements. CONCLUSIONS: We propose that CIE Metric Lightness could be used as the contrast measure. Alternatively, Michelson contrast is the most perceptually linear of the current measurement scales.

scholarly journals Transition Scale-Spaces: A Computational Theory for the Discretized Entorhinal Cortex

2020 ◽  
Vol 32 (2) ◽  
pp. 330-394
Author(s):  
Nicolai Waniek
Keyword(s):  
Data Structure ◽  
Theoretical Model ◽  
Entorhinal Cortex ◽  
Receptive Fields ◽  
Grid Cell ◽  
Scale Space ◽  
General Purpose ◽  
Single Scale ◽  
Scale Spaces ◽  
Space Data

Although hippocampal grid cells are thought to be crucial for spatial navigation, their computational purpose remains disputed. Recently, they were proposed to represent spatial transitions and convey this knowledge downstream to place cells. However, a single scale of transitions is insufficient to plan long goal-directed sequences in behaviorally acceptable time. Here, a scale-space data structure is suggested to optimally accelerate retrievals from transition systems, called transition scale-space (TSS). Remaining exclusively on an algorithmic level, the scale increment is proved to be ideally [Formula: see text] for biologically plausible receptive fields. It is then argued that temporal buffering is necessary to learn the scale-space online. Next, two modes for retrieval of sequences from the TSS are presented: top down and bottom up. The two modes are evaluated in symbolic simulations (i.e., without biologically plausible spiking neurons). Additionally, a TSS is used for short-cut discovery in a simulated Morris water maze. Finally, the results are discussed in depth with respect to biological plausibility, and several testable predictions are derived. Moreover, relations to other grid cell models, multiresolution path planning, and scale-space theory are highlighted. Summarized, reward-free transition encoding is shown here, in a theoretical model, to be compatible with the observed discretization along the dorso-ventral axis of the medial entorhinal cortex. Because the theoretical model generalizes beyond navigation, the TSS is suggested to be a general-purpose cortical data structure for fast retrieval of sequences and relational knowledge. Source code for all simulations presented in this paper can be found at https://github.com/rochus/transitionscalespace .

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