Spatio-temporal constraints of the tidal wave theory

1997 ◽  
Vol 20 (2) ◽  
pp. 264-265
Author(s):  
Cornelius Schwarz
Keyword(s):  
Purkinje Cell ◽  
Input Sequence ◽  
Wave Theory ◽  
Tidal Wave ◽  
Minimal Distance ◽  
Temporal Precision ◽  
Tidal Waves ◽  
Temporal And Spatial ◽  
Spatio Temporal ◽  
Cortical Inputs

The tidal-wave theory is inspired by the particular morphology of the cerebellar cortex. It elegantly attributes function to the anisotropy of the cerebellar wiring and the geometry of Purkinje cell dendrites. In this commentary, physiological considerations are used to elaborate temporal and spatial constraints of the tidal-wave theory. It is shown, first, that limitations of temporal precision in the cortical inputs to the mammalian cerebellum delimit the spatial resolution of an input sequence (i.e., the minimal distance along the parallel fibers which can detect sequential input) to the range of a millimeter at best. Second, temporal characteristics of Purkinje cell postsynaptic potentials are argued to predict a distance of at least several millimeters along the parallel fiber beam in order to generate a sequence in the cerebellar output. It is concluded that the implementation of tidal waves as a general principle of cerebellar function is questionable as there exist cerebelli too small to match these constraints.

Elucidating cyclic AMP signaling in subcellular domains with optogenetic tools and fluorescent biosensors

2019 ◽  
Vol 47 (6) ◽  
pp. 1733-1747 ◽  
Author(s):  
Christina Klausen ◽  
Fabian Kaiser ◽  
Birthe Stüven ◽  
Jan N. Hansen ◽  
Dagmar Wachten
Keyword(s):  
Cyclic Amp ◽  
Adenosine Monophosphate ◽  
Adenylyl Cyclases ◽  
Temporal Precision ◽  
Fluorescent Biosensors ◽  
Subcellular Domains ◽  
Spatio Temporal ◽  
Hydrolysis Of ◽  
Shed Light ◽  
Cyclic Amp Signaling

The second messenger 3′,5′-cyclic nucleoside adenosine monophosphate (cAMP) plays a key role in signal transduction across prokaryotes and eukaryotes. Cyclic AMP signaling is compartmentalized into microdomains to fulfil specific functions. To define the function of cAMP within these microdomains, signaling needs to be analyzed with spatio-temporal precision. To this end, optogenetic approaches and genetically encoded fluorescent biosensors are particularly well suited. Synthesis and hydrolysis of cAMP can be directly manipulated by photoactivated adenylyl cyclases (PACs) and light-regulated phosphodiesterases (PDEs), respectively. In addition, many biosensors have been designed to spatially and temporarily resolve cAMP dynamics in the cell. This review provides an overview about optogenetic tools and biosensors to shed light on the subcellular organization of cAMP signaling.

Is the cerebellum essentially a precise pattern matching device?

1997 ◽  
Vol 20 (2) ◽  
pp. 257-257
Author(s):  
Franz Mechsner ◽  
Günther Palm
Keyword(s):  
Pattern Matching ◽  
Cerebellar Cortex ◽  
Wave Theory ◽  
Tidal Wave ◽  
Cerebellar Function ◽  
Moving Stimuli ◽  
Theoretical Claim ◽  
The Common

(1) The “timing idea” is not the only interpretation of cerebellar histology worth considering. Therefore, it is not imperative to strive for a theory of cerebellar function which gives it a prominent rôle. (2) The experiments with “moving stimuli” cannot support the tidal wave theory. (3) The notion that only “moving stimuli” can excite the cerebellar cortex is burdened with many intrinsic difficulties. (4) The common theoretical claim that the accuracy of skilled movements is due to exact pattern-matching processes in the cerebellum may be most misleading.

VIDEO-SHOT TRANSITION DETECTION: A SPATIO-TEMPORAL SALIENCY APPROACH

2010 ◽  
Vol 24 (08) ◽  
pp. 1295-1309 ◽  
Author(s):  
XIAN WU ◽  
JIANHUANG LAI ◽  
PONG C. YUEN
Keyword(s):  
Error Probability ◽  
Spatial Information ◽  
Saliency Map ◽  
Detection Error ◽  
Novel Approach ◽  
Video Shot ◽  
Recent Method ◽  
Temporal And Spatial ◽  
Spatio Temporal ◽  
Shot Transitions

This paper proposes a novel approach for video-shot transition detection using spatio-temporal saliency. Both temporal and spatial information are combined to generate a saliency map, and features are available based on the change of saliency. Considering the context of shot changes, a statistical detector is constructed to determine all types of shot transitions by the minimization of the detection-error probability simultaneously under the same framework. The evaluation performed on videos of various content types demonstrates that the proposed approach outperforms a more recent method and two publicly available systems, namely VideoAnnex and VCM.

scholarly journals Iterated Local Search for Time-extended Multi-robot Task Allocation with Spatio-temporal and Capacity Constraints

2019 ◽  
Vol 28 (2) ◽  
pp. 347-360 ◽  
Author(s):  
Hakim Mitiche ◽  
Dalila Boughaci ◽  
Maria Gini
Keyword(s):  
Local Search ◽  
Task Allocation ◽  
Iterated Local Search ◽  
Spatial Constraints ◽  
Parameters Tuning ◽  
Temporal And Spatial ◽  
Spatio Temporal ◽  
Robot Task ◽  
Time Critical ◽  
Multi Robot

Abstract We propose a method for task allocation to multiple physical agents that works when tasks have temporal and spatial constraints and agents have different capacities. Assuming that the problem is over-constrained, we need to find allocations that maximize the number of tasks that can be done without violating any of the constraints. The contribution of this work is the study of a new multi-robot task allocation problem and the design and the experimental evaluation of our approach, an iterated local search that is suitable for time critical applications. We created test instances on which we experimentally show that our approach outperforms a state-of-the-art approach to a related problem. Our approach improves the baseline’s score on average by 2.35% and up to 10.53%, while responding in times shorter than the baseline’s, on average, 1.6 s and up to 5.5 s shorter. Furthermore, our approach is robust to run replication and is not very sensitive to parameters tuning.

scholarly journals Functionally distinct Purkinje cell types show temporal precision in encoding locomotion

2020 ◽  
Vol 117 (29) ◽  
pp. 17330-17337
Author(s):  
Weipang Chang ◽  
Andrea Pedroni ◽  
Victoria Hohendorf ◽  
Stefania Giacomello ◽  
Masahiko Hibi ◽  
...  
Keyword(s):  
Purkinje Cell ◽  
Purkinje Cells ◽  
Central Pattern Generators ◽  
Cell Types ◽  
Neuronal Population ◽  
Adult Zebrafish ◽  
Temporal Precision ◽  
Distinct Cell ◽  
Pattern Generators ◽  
Cell Networks

Purkinje cells, the principal neurons of cerebellar computations, are believed to comprise a uniform neuronal population of cells, each with similar functional properties. Here, we show an undiscovered heterogeneity of adult zebrafish Purkinje cells, revealing the existence of anatomically and functionally distinct cell types. Dual patch-clamp recordings showed that the cerebellar circuit contains all Purkinje cell types that cross-communicate extensively using chemical and electrical synapses. Further activation of spinal central pattern generators (CPGs) revealed unique phase-locked activity from each Purkinje cell type during the locomotor cycle. Thus, we show intricately organized Purkinje cell networks in the adult zebrafish cerebellum that encode the locomotion rhythm differentially, and we suggest that these organizational properties may also apply to other cerebellar functions.

Phonological disorders and spatio‐temporal precision of stop consonant gestures

1998 ◽  
Vol 104 (3) ◽  
pp. 1853-1853
Author(s):  
Jan Edwards ◽  
Marios Fourakis ◽  
Mary Beckman ◽  
Pauline Welby ◽  
Ying Xu
Keyword(s):  
Stop Consonant ◽  
Temporal Precision ◽  
Phonological Disorders ◽  
Spatio Temporal

scholarly journals Re-Arranging Space, Time and Scales in GIS: Alternative Models for Multi-Scale Spatio-Temporal Modeling and Analyses

2019 ◽  
Vol 8 (2) ◽  
pp. 72 ◽  
Author(s):  
Yi Qiang ◽  
Nico Van de Weghe
Keyword(s):  
Spatial Data ◽  
Spatial Scales ◽  
Space Time ◽  
Unified Framework ◽  
Temporal Modeling ◽  
Multi Scale ◽  
Space And Time ◽  
Pyramid Model ◽  
Temporal And Spatial ◽  
Spatio Temporal

The representations of space and time are fundamental issues in GIScience. In prevalent GIS and analytical systems, time is modeled as a linear stream of real numbers and space is represented as flat layers with timestamps. Despite their dominance in GIS and information visualization, these representations are inefficient for visualizing data with complex temporal and spatial extents and the variation of data at multiple temporal and spatial scales. This article presents alternative representations that incorporate the scale dimension into time and space. The article first reviews a series of work about the triangular model (TM), which is a multi-scale temporal model. Then, it introduces the pyramid model (PM), which is the extension of the TM for spatial data, and demonstrates the utility of the PM in visualizing multi-scale spatial patterns of land cover data. Finally, it discusses the potential of integrating the TM and the PM into a unified framework for multi-scale spatio-temporal modeling. This article systematically documents the models with alternative arrangements of space and time and their applications in analyzing different types of data. Additionally, this article aims to inspire the re-thinking of organizations of space, time, and scales in the future development of GIS and analytical tools to handle the increasing quantity and complexity of spatio-temporal data.

scholarly journals Uncovering Spatio-temporal Travel Patterns Using a Tensor-based Model from Metro Smart Card Data in Shenzhen, China

2020 ◽  
Vol 12 (4) ◽  
pp. 1475 ◽  
Author(s):  
Jinjun Tang ◽  
Xiaolu Wang ◽  
Fang Zong ◽  
Zheng Hu
Keyword(s):  
Temporal Distribution ◽  
Spatial Dimension ◽  
Urban Traffic ◽  
Travel Patterns ◽  
Mobility Patterns ◽  
Shenzhen City ◽  
Temporal And Spatial ◽  
Spatio Temporal ◽  
Temporal Dimensions ◽  
Metro Network

Individual mobility patterns are an important factor in urban traffic planning and traffic flow forecasting. How to understand the spatio-temporal distribution of passengers deeply and accurately, so as to provide theoretical support for the planning and operation of the metro network, is an urgent issue of wide concern. In this paper, we applied NCP decomposition to uncover the characteristics of travel patterns from temporal and spatial dimensions in the metro network of Shenzhen City. Utilizing matrix factorization and correlation analysis, we extracted several stable components from the collective mobility and find that the departure and arrival mobility patterns have different characteristics in both the temporal and spatial dimension. According to the point of interest (POI) data in the Shenzhen City, the function attributes of the station are identified and then we found that the spatial distribution characteristics of different patterns are different. We explored the distribution of travel time classified according to the spatio-temporal characteristics of stable patterns. The proposed method can decompose stable travel patterns from the collective mobility and the results in this study can help us to better understand different mobility patterns in both spatial and temporal dimensions.

scholarly journals Temporal and spatial variation in age-specific survival rates of a long-lived mammal, the Hawaiian monk seal

2006 ◽  
Vol 274 (1608) ◽  
pp. 407-415 ◽  
Author(s):  
Jason D Baker ◽  
Paul M Thompson
Keyword(s):  
Survival Rates ◽  
Adult Survival ◽  
Age Classes ◽  
Temporal And Spatial Variation ◽  
Monachus Schauinslandi ◽  
Breeding Sites ◽  
Capture Recapture ◽  
Temporal And Spatial ◽  
Spatio Temporal ◽  
Monk Seals

Estimates of variability in pinniped survival rates are generally based on observations at single sites, so it is not certain whether observed rates represent the whole population. Here, we provide a comprehensive analysis of spatio-temporal variation in age-specific survival rates for endangered Hawaiian monk seals ( Monachus schauinslandi ) based on capture–recapture analyses of more than 85% of the pups weaned in this population over the last two decades. Uniquely, these data have been collected from six subpopulations, encompassing all major breeding sites across its 1800 km long core range. Analyses of individual subpopulations revealed similar patterns in age-specific survival, characterized by the relatively low survival rates from weaning to 2 years of age, intermediate rates to 4 years of age, and then by relatively high ‘mature’ survival rates until 17 years of age, after which a senescent decline was observed. Juvenile, subadult and adult survival rates all varied significantly over time. Trends in survival among subpopulations were coherent with their relative geographical positions, suggesting regional structuring and connectedness within the archipelago. Survival rates for different age classes tended to be positively correlated, suggesting that similar factors may influence the survival for seals of all ages.

Finite tidal waves propagated without change of shape

1960 ◽  
Vol 9 (4) ◽  
pp. 506-512 ◽  
Author(s):  
F. K. Ball
Keyword(s):  
Classical Result ◽  
Tidal Wave ◽  
Tidal Waves

Coriolis terms are introduced into the equations governing the motion of a finite tidal wave. Various types of solution are found, all of which travel without change of shape and some which are periodic with sharp crests and broad troughs. The classical result that such waves cannot be propagated without change of shape is therefore untrue in these circumstances.

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