scholarly journals Neural decoding of visual stimuli varies with fluctuations in global network efficiency

2017 ◽  
Author(s):  
Luca Cocchi ◽  
Yang Zhengyi ◽  
Zalesky Andrew ◽  
Stelzer Johannes ◽  
Luke Hearne ◽  
...  
Keyword(s):  
Neural Activity ◽  
Global Network ◽  
Network Efficiency ◽  
Time Resolved ◽  
Sensory Stimuli ◽  
Global Efficiency ◽  
Low Efficiency ◽  
Cortical Regions ◽  
Visual Cortical ◽  
The Impact

AbstractFunctional magnetic resonance imaging (fMRI) studies have shown that neural activity fluctuates spontaneously between different states of global synchronization over a timescale of several seconds. Such fluctuations generate transient states of high and low correlation across distributed cortical areas. It has been hypothesized that such fluctuations in global efficiency might alter patterns of activity in local neuronal populations elicited by changes in incoming sensory stimuli. To test this prediction, we used a linear decoder to discriminate patterns of neural activity elicited by face and motion stimuli presented periodically while participants underwent time-resolved fMRI. As predicted, decoding was reliably higher during states of high global efficiency than during states of low efficiency, and this difference was evident across both visual and non-visual cortical regions. The results indicate that slow fluctuations in global network efficiency are associated with variations in the pattern of activity across widespread cortical regions responsible for representing distinct categories of visual stimulus. More broadly, the findings highlight the importance of understanding the impact of global fluctuations in functional connectivity on specialised, stimulus driven neural processes.

scholarly journals Conflicts in Routing and UAV Autonomy

2018 ◽  
Vol 6 (4) ◽  
pp. 96-108 ◽  
Author(s):  
Ogbonnaya Anicho ◽  
Philip B Charlesworth ◽  
Gurvinder S Baicher ◽  
Atulya Nagar
Keyword(s):  
Network Architecture ◽  
Ad Hoc ◽  
Area Coverage ◽  
Global Network ◽  
Network Efficiency ◽  
Aerial Vehicle ◽  
Routing Techniques ◽  
Stability Issues ◽  
Link Availability ◽  
The Impact

Routing is very fundamental to the implementation of any networking or communications infrastructure. This paper, therefore, examines the conflicts and relevant considerations for implementing autonomous or self-organising unmanned aerial vehicles (UAVs) for communications area coverage, with particular emphasis on the impact of aerial vehicle autonomy algorithms on routing techniques for such networks. UAV networks can be deployed either as ad-hoc or infrastructure-based solutions. The mobility of UAVs introduces periodic topology changes, impacting link availability and routing paths. This work examines the implications of autonomous coordination of multiple UAVs on routing techniques and network architecture stability. The paper proposes a solution where routing techniques and UAV autonomy algorithms are integrated for improved global network efficiency for both ad-hoc and infrastructure-based scenarios. Integrating UAV autonomy algorithms with routing schemes may be an efficient method to mitigate link/topology stability issues and improve inter-UAV communication and network throughput, a key requirement for UAV networks. The implementation of inter-UAV links using optical, microwave or mmWave transmission is examined in the context of this work. The proposed integration may be crucial for communications coverage, where UAVs provide communications area coverage of a community of mobile or fixed users in either ad-hoc or infrastructure-based modes.

scholarly journals Network Path Convergence Shapes Low-Level Processing in the Visual Cortex

2021 ◽  
Vol 15 ◽  
Author(s):  
Bálint Varga ◽  
Bettina Soós ◽  
Balázs Jákli ◽  
Eszter Bálint ◽  
Zoltán Somogyvári ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Large Scale ◽  
Global Network ◽  
Network Efficiency ◽  
Beta Band ◽  
Low Level ◽  
Cortical Areas ◽  
Edge Betweenness ◽  
Highly Correlated ◽  
Visual Cortical

Hierarchical counterstream via feedforward and feedback interactions is a major organizing principle of the cerebral cortex. The counterstream, as a topological feature of the network of cortical areas, is captured by the convergence and divergence of paths through directed links. So defined, the convergence degree (CD) reveals the reciprocal nature of forward and backward connections, and also hierarchically relevant integrative properties of areas through their inward and outward connections. We asked if topology shapes large-scale cortical functioning by studying the role of CD in network resilience and Granger causal coupling in a model of hierarchical network dynamics. Our results indicate that topological synchronizability is highly vulnerable to attacking edges based on CD, while global network efficiency depends mostly on edge betweenness, a measure of the connectedness of a link. Furthermore, similar to anatomical hierarchy determined by the laminar distribution of connections, CD highly correlated with causal coupling in feedforward gamma, and feedback alpha-beta band synchronizations in a well-studied subnetwork, including low-level visual cortical areas. In contrast, causal coupling did not correlate with edge betweenness. Considering the entire network, the CD-based hierarchy correlated well with both the anatomical and functional hierarchy for low-level areas that are far apart in the hierarchy. Conversely, in a large part of the anatomical network where hierarchical distances are small between the areas, the correlations were not significant. These findings suggest that CD-based and functional hierarchies are interrelated in low-level processing in the visual cortex. Our results are consistent with the idea that the interplay of multiple hierarchical features forms the basis of flexible functional cortical interactions.

scholarly journals Conflicts in Routing and UAV Autonomy

2018 ◽  
Vol 6 (4) ◽  
pp. 96-108
Author(s):  
Ogbonnaya Anicho ◽  
Philip B Charlesworth ◽  
Gurvinder S Baicher ◽  
Atulya Nagar
Keyword(s):  
Network Architecture ◽  
Ad Hoc ◽  
Area Coverage ◽  
Global Network ◽  
Network Efficiency ◽  
Aerial Vehicle ◽  
Routing Techniques ◽  
Stability Issues ◽  
Link Availability ◽  
The Impact

Routing is very fundamental to the implementation of any networking or communications infrastructure. This paper, therefore, examines the conflicts and relevant considerations for implementing autonomous or self-organising unmanned aerial vehicles (UAVs) for communications area coverage, with particular emphasis on the impact of aerial vehicle autonomy algorithms on routing techniques for such networks. UAV networks can be deployed either as ad-hoc or infrastructure-based solutions. The mobility of UAVs introduces periodic topology changes, impacting link availability and routing paths. This work examines the implications of autonomous coordination of multiple UAVs on routing techniques and network architecture stability. The paper proposes a solution where routing techniques and UAV autonomy algorithms are integrated for improved global network efficiency for both ad-hoc and infrastructure-based scenarios. Integrating UAV autonomy algorithms with routing schemes may be an efficient method to mitigate link/topology stability issues and improve inter-UAV communication and network throughput, a key requirement for UAV networks. The implementation of inter-UAV links using optical, microwave or mmWave transmission is examined in the context of this work. The proposed integration may be crucial for communications coverage, where UAVs provide communications area coverage of a community of mobile or fixed users in either ad-hoc or infrastructure-based modes.

Cloud computing demand elasticity algorithm based on ant colony algorithm

2020 ◽  
Vol 13 ◽  
Author(s):  
Chunyu Liu ◽  
Fengrui Mu ◽  
Weilong Zhang
Keyword(s):  
Ant Colony Algorithm ◽  
Theory Of Elasticity ◽  
Ant Colony ◽  
Demand Elasticity ◽  
Network Efficiency ◽  
Elasticity Of Demand ◽  
Operating Profit ◽  
Network Load ◽  
Network Utilization ◽  
The Impact

Background: In recent era of technology, the traditional Ant Colony Algorithm (ACO) is insufficient in solving the problem of network congestion and load balance, and network utilization. Methods: This paper proposes an improved ant colony algorithm, which considers the price factor based on the theory of elasticity of demand. The price factor is denominated in the impact on the network load which means indirect control of network load, congestion or auxiliary solution to calculate the idle resources caused by the low network utilization and reduced profits. Results: Experimental results show that the improved algorithm can balance the overall network load, extend the life of path by nearly 3 hours, greatly reduce the risk of network paralysis, and increase the profit of the manufacturer by 300 million Yuan. Conclusion: Furthermore, results shows that the improved method has a great application value in improving the network efficiency, balancing network load, prolonging network life and increasing network operating profit.

scholarly journals The Role of Primate Prefrontal Cortex in Bias and Shift Between Visual Dimensions

2019 ◽  
Vol 30 (1) ◽  
pp. 85-99 ◽  
Author(s):  
Farshad A Mansouri ◽  
Mark J Buckley ◽  
Daniel J Fehring ◽  
Keiji Tanaka
Keyword(s):  
Prefrontal Cortex ◽  
Anterior Cingulate ◽  
Top Down ◽  
Attentional Processes ◽  
Prefrontal Cortical ◽  
Frontopolar Cortex ◽  
Dorsolateral Prefrontal ◽  
Cortical Regions ◽  
Visual Cortical ◽  
Bilateral Lesions

Abstract Imaging and neural activity recording studies have shown activation in the primate prefrontal cortex when shifting attention between visual dimensions is necessary to achieve goals. A fundamental unanswered question is whether representations of these dimensions emerge from top-down attentional processes mediated by prefrontal regions or from bottom-up processes within visual cortical regions. We hypothesized a causative link between prefrontal cortical regions and dimension-based behavior. In large cohorts of humans and macaque monkeys, performing the same attention shifting task, we found that both species successfully shifted between visual dimensions, but both species also showed a significant behavioral advantage/bias to a particular dimension; however, these biases were in opposite directions in humans (bias to color) versus monkeys (bias to shape). Monkeys’ bias remained after selective bilateral lesions within the anterior cingulate cortex (ACC), frontopolar cortex, dorsolateral prefrontal cortex (DLPFC), orbitofrontal cortex (OFC), or superior, lateral prefrontal cortex. However, lesions within certain regions (ACC, DLPFC, or OFC) impaired monkeys’ ability to shift between these dimensions. We conclude that goal-directed processing of a particular dimension for the executive control of behavior depends on the integrity of prefrontal cortex; however, representation of competing dimensions and bias toward them does not depend on top-down prefrontal-mediated processes.

scholarly journals The Impact of Energy Consumption on the Three Pillars of Sustainable Development

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1372
Author(s):  
Silviu Nate ◽  
Yuriy Bilan ◽  
Danylo Cherevatskyi ◽  
Ganna Kharlamova ◽  
Oleksandr Lyakh ◽  
...  
Keyword(s):  
Sustainable Development ◽  
Energy Consumption ◽  
Energy Density ◽  
Ecological Footprint ◽  
Policy Design ◽  
Disability Adjusted Life ◽  
The Social ◽  
Low Efficiency ◽  
Disability Adjusted Life Year ◽  
The Impact

The paper analyzes the impact of energy consumption on the three pillars of sustainable development in 74 countries. The main methodological challenge in this research is the choice of a single integral indicator for assessing the social component of sustainable development. Disability-adjusted life year (DALY), ecological footprint, and GDP (Gross domestic product) are used to characterize the social, ecological, and economical pillars. The concept of physics, namely the concept of density (specific gravity), is used. It characterizes the ratio of the mass of a substance to its volume, i.e., reflects the saturation of a certain volume with this substance. Thus, to assess the relationship between energy consumption and the three foundations of sustainable development, it is proposed to determine the energy density of the indicators DALY, the ecological footprint, and GDP. The reaction to changes in energy consumption is described by the elasticity of energy density functions, calculated for each of the abovementioned indicators. The state of the social pillar is mostly dependent on energy consumption. As for the changes in the ecological pillar, a 1% reduction in energy consumption per capita gives only a 0.6% ecological footprint reduction, which indicates a low efficiency of reducing energy consumption policy and its danger for the social pillar. The innovative aspect of the research is to apply a cross-disciplinary approach and a calculative technique to identify the impact that each of the pillars of sustainable development imposes on energy policy design. The policy of renewable energy expansion is preferable for all sustainable development pillars.

scholarly journals Reconfiguration of human evolving large-scale epileptic brain networks prior to seizures: an evaluation with node centralities

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Rieke Fruengel ◽  
Timo Bröhl ◽  
Thorsten Rings ◽  
Klaus Lehnertz
Keyword(s):  
Large Scale ◽  
Brain Networks ◽  
Brain Regions ◽  
Brain Network ◽  
Theoretical Concept ◽  
Global Network ◽  
Time Resolved ◽  
Functional Connections ◽  
Node Centrality ◽  
Network Mechanism

AbstractPrevious research has indicated that temporal changes of centrality of specific nodes in human evolving large-scale epileptic brain networks carry information predictive of impending seizures. Centrality is a fundamental network-theoretical concept that allows one to assess the role a node plays in a network. This concept allows for various interpretations, which is reflected in a number of centrality indices. Here we aim to achieve a more general understanding of local and global network reconfigurations during the pre-seizure period as indicated by changes of different node centrality indices. To this end, we investigate—in a time-resolved manner—evolving large-scale epileptic brain networks that we derived from multi-day, multi-electrode intracranial electroencephalograpic recordings from a large but inhomogeneous group of subjects with pharmacoresistant epilepsies with different anatomical origins. We estimate multiple centrality indices to assess the various roles the nodes play while the networks transit from the seizure-free to the pre-seizure period. Our findings allow us to formulate several major scenarios for the reconfiguration of an evolving epileptic brain network prior to seizures, which indicate that there is likely not a single network mechanism underlying seizure generation. Rather, local and global aspects of the pre-seizure network reconfiguration affect virtually all network constituents, from the various brain regions to the functional connections between them.

scholarly journals Impact of generalized brain arousal on sexual behavior

2010 ◽  
Vol 107 (5) ◽  
pp. 2265-2270 ◽  
Author(s):  
Zachary M. Weil ◽  
Qiuyu Zhang ◽  
Allison Hornung ◽  
David Blizard ◽  
Donald W. Pfaff
Keyword(s):  
Emotional Reactivity ◽  
Behavioral Arousal ◽  
Sensory Stimuli ◽  
Vertebrate Brain ◽  
Plus Maze ◽  
Initial Activation ◽  
High Level ◽  
Global Brain ◽  
Motivated Behaviors ◽  
The Impact

Although there is an extensive amount known about specific sensory and motor functions of the vertebrate brain, less is understood about the regulation of global brain states. We have recently proposed that a function termed generalized arousal (Ag) serves as the most elemental driving force in the nervous system, responsible for the initial activation of all behavioral responses. An animal with increased generalized CNS arousal is characterized by greater motor activity, increased responsivity to sensory stimuli, and greater emotional lability. Implicit in this theory was the prediction that increases in generalized arousal would augment specific motivated behaviors that depend on arousal. Here, we address the idea directly by testing two lines of mice bred for high or low levels of generalized arousal and assessing their responses in tests of specific forms of behavioral arousal, sex and anxiety/exploration. We report that animals selected for differential generalized arousal exhibit marked increases in sensory, motor, and emotional reactivity in our arousal assay. Furthermore, male mice selected for high levels of generalized arousal were excitable and showed more incomplete mounts before the first intromission (IN), but having achieved that IN, they exhibited far fewer IN before ejaculating, as well as ejaculating much sooner after the first IN, thus indicating a high level of sexual arousal. Additionally, high-arousal animals of both sexes exhibited greater levels of anxiety-like behaviors and reduced exploratory behavior in the elevated plus maze and light-dark box tasks. Taken together, these data illustrate the impact of Ag on motivated behaviors.

scholarly journals Identification and Quantification of Node Criticality through EWM–TOPSIS: A Study of Hong Kong’s MTR System

2021 ◽  
Author(s):  
Yifan Zhang ◽  
S. Thomas Ng
Keyword(s):  
Hong Kong ◽  
Public Transportation ◽  
Early Stage ◽  
Network Robustness ◽  
Global Network ◽  
Practical Significance ◽  
Topsis Method ◽  
Urban Resilience ◽  
Network Efficiency ◽  
Entropy Weight

AbstractPublic transport networks (PTNs) are critical in populated and rapidly densifying cities such as Hong Kong, Beijing, Shanghai, Mumbai, and Tokyo. Public transportation plays an indispensable role in urban resilience with an integrated, complex, and dynamically changeable network structure. Consequently, identifying and quantifying node criticality in complex PTNs is of great practical significance to improve network robustness from damage. Despite the proposition of various node criticality criteria to address this problem, few succeeded in more comprehensive aspects. Therefore, this paper presents an efficient and thorough ranking method, that is, entropy weight method (EWM)–technology for order preference by similarity to an ideal solution (TOPSIS), named EWM–TOPSIS, to evaluate node criticality by taking into account various node features in complex networks. Then we demonstrate it on the Mass Transit Railway (MTR) in Hong Kong by removing and recovering the top k critical nodes in descending order to compare the effectiveness of degree centrality (DC), betweenness centrality (BC), closeness centrality (CC), and the proposed EWM–TOPSIS method. Four evaluation indicators, that is, the frequency of nodes with the same ranking (F), the global network efficiency (E), the size of the largest connected component (LCC), and the average path length (APL), are computed to compare the performance of the four methods and measure network robustness under different designed attack and recovery strategies. The results demonstrate that the EWM–TOPSIS method has more obvious advantages than the others, especially in the early stage.

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