scholarly journals Spatiotemporal dynamics of maximal and minimal EEG spectral power

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0253813
Author(s):  
Melisa Menceloglu ◽  
Marcia Grabowecky ◽  
Satoru Suzuki
Keyword(s):  
Large Scale ◽  
Stochastic Dynamics ◽  
Spectral Power ◽  
Spatiotemporal Dynamics ◽  
Small Scale ◽  
Neural Activities ◽  
Eeg Spectral Power ◽  
Neural Communication ◽  
Scale Network ◽  
Large Scale Networks

Oscillatory neural activities are prevalent in the brain with their phase realignment contributing to the coordination of neural communication. Phase realignments may have especially strong (or weak) impact when neural activities are strongly synchronized (or desynchronized) within the interacting populations. We report that the spatiotemporal dynamics of strong regional synchronization measured as maximal EEG spectral power—referred to as activation—and strong regional desynchronization measured as minimal EEG spectral power—referred to as suppression—are characterized by the spatial segregation of small-scale and large-scale networks. Specifically, small-scale spectral-power activations and suppressions involving only 2–7% (1–4 of 60) of EEG scalp sites were prolonged (relative to stochastic dynamics) and consistently co-localized in a frequency specific manner. For example, the small-scale networks for θ, α, β1, and β2 bands (4–30 Hz) consistently included frontal sites when the eyes were closed, whereas the small-scale network for γ band (31–55 Hz) consistently clustered in medial-central-posterior sites whether the eyes were open or closed. Large-scale activations and suppressions involving over 17–30% (10–18 of 60) of EEG sites were also prolonged and generally clustered in regions complementary to where small-scale activations and suppressions clustered. In contrast, intermediate-scale activations and suppressions (involving 7–17% of EEG sites) tended to follow stochastic dynamics and were less consistently localized. These results suggest that strong synchronizations and desynchronizations tend to occur in small-scale and large-scale networks that are spatially segregated and frequency specific. These synchronization networks may broadly segregate the relatively independent and highly cooperative oscillatory processes while phase realignments fine-tune the network configurations based on behavioral demands.

scholarly journals Spatiotemporal dynamics of maximal and minimal EEG spectral power

2021 ◽  
Author(s):  
Melisa Menceloglu ◽  
Marcia Grabowecky ◽  
Satoru Suzuki
Keyword(s):  
Large Scale ◽  
Stochastic Dynamics ◽  
Spectral Power ◽  
Spatiotemporal Dynamics ◽  
Small Scale ◽  
Neural Activities ◽  
Eeg Spectral Power ◽  
Neural Communication ◽  
Scale Network ◽  
Large Scale Networks

AbstractOscillatory neural activities are prevalent in the brain with their phase realignment contributing to the coordination of neural communication. Phase realignments would have especially strong (or weak) impact when neural activities are strongly synchronized (or desynchronized) within the interacting sub-populations. We report that the spatiotemporal dynamics of strong regional synchronization (reflected in maximal EEG spectral power)—activation—and strong regional desynchronization (reflected in minimal EEG spectral power)—suppression—are characterized by the spatial segregation of isolated small-scale networks and highly cooperative large-scale networks. Specifically, small-scale spectral-power activations and suppressions involving only 2%–7% of EEG scalp sites were prolonged (relative to stochastic dynamics) and consistently co-localized in a frequency specific manner. For example, the small-scale networks for θ, α, β1, and β2 bands (4–30 Hz) consistently included frontal sites when the eyes were closed, whereas the small-scale network for γ band (31–55 Hz) consistently clustered in medial-central-posterior sites whether the eyes were open or closed. Large-scale activations and suppressions involving over 30% of EEG sites were also prolonged and generally clustered in regions complementary to where small-scale activations and suppressions clustered. In contrast, intermediate-scale activations and suppressions tended to follow stochastic dynamics and were less consistently localized. These results suggest that strong synchronizations and desynchronizations occur in small-scale and large-scale networks that are spatially segregated and frequency specific. These synchronization networks may broadly segregate the relatively independent and highly cooperative oscillatory processes while phase realignments fine-tune the network configurations based on behavioral demands.

The power distribution between the symmetric and anti-symmetric components of the tropical wavenumber-frequency spectrum

2021 ◽  
Author(s):  
Ofer Shamir ◽  
Chen Schwartz ◽  
Chaim Garfinkel ◽  
Nathan Paldor
Keyword(s):  
Frequency Spectrum ◽  
Power Distribution ◽  
Large Scale ◽  
Spectral Power ◽  
Spatial Scales ◽  
Turbulent Energy ◽  
Heat Fluxes ◽  
Small Scale ◽  
Ample Evidence ◽  
Parity Distribution

<p>A yet unexplained feature of the tropical wavenumber-frequency spectrum is its parity distributions, i.e., the distribution of power between the meridionally symmetric and anti-symmetric components of the spectrum. Due to the linearity of the decomposition to symmetric and anti-symmetric components and the Fourier analysis, the total spectral power equals the sum of the power contained in each of these two components. However, the spectral power need not be evenly distributed between the two components. Satellite observations and reanalysis data provide ample evidence that the parity distribution of the tropical wavenumber-frequency spectrum is biased towards its symmetric component. Using an intermediate-complexity model of an idealized moist atmosphere, we find that the parity distribution of the tropical spectrum is nearly insensitive to large-scale forcing, including topography, ocean heat fluxes, and land-sea contrast. On the other hand, by adding a small-scale (stochastic) forcing, we find that the parity distribution of the tropical spectrum is sensitive to asymmetries on small spatial scales compared to the observed large-scale spectrum. Physically, such forcing can be thought of as small-scale convection, which is believed to trigger some of the Tropics' large-scale features via an upscale (inverse) turbulent energy cascade. These results are qualitatively explained by considering the effects of triad interactions on the parity distribution. According to the proposed mechanism, any small-scale asymmetry (symmetric or anti-symmetric) in the forcing leads to symmetric bias in the spectrum, regardless of the source of variability providing the forcing.</p>

Synchrony of Neuronal Oscillations Controlled by GABAergic Reversal Potentials

2007 ◽  
Vol 19 (3) ◽  
pp. 706-729 ◽  
Author(s):  
Ho Young Jeong ◽  
Boris Gutkin
Keyword(s):  
Large Scale ◽  
Reversal Potential ◽  
Type I ◽  
Gabaergic Synapse ◽  
Neural Oscillators ◽  
Large Scale Network ◽  
Weakly Coupled ◽  
Scale Network ◽  
Large Scale Networks

GABAergic synapse reversal potential is controlled by the concentration of chloride. This concentration can change significantly during development and as a function of neuronal activity. Thus, GABA inhibition can be hyperpolarizing, shunting, or partially depolarizing. Previous results pinpointed the conditions under which hyperpolarizing inhibition (or depolarizing excitation) can lead to synchrony of neural oscillators. Here we examine the role of the GABAergic reversal potential in generation of synchronous oscillations in circuits of neural oscillators. Using weakly coupled oscillator analysis, we show when shunting and partially depolarizing inhibition can produce synchrony, asynchrony, and coexistence of the two. In particular, we show that this depends critically on such factors as the firing rate, the speed of the synapse, spike frequency adaptation, and, most important, the dynamics of spike generation (type I versus type II). We back up our analysis with simulations of small circuits of conductance-based neurons, as well as large-scale networks of neural oscillators. The simulation results are compatible with the analysis: for example, when bistability is predicted analytically, the large-scale network shows clustered states.

scholarly journals Lightweight Label Propagation for Large-Scale Network Data

2018 ◽  
Author(s):  
De-Ming Liang ◽  
Yu-Feng Li
Keyword(s):  
Large Scale ◽  
Label Propagation ◽  
Stochastic Gradient Descent ◽  
Small Scale ◽  
Warm Start ◽  
Large Scale Data ◽  
Large Scale Network ◽  
Memory Overhead ◽  
Scale Network ◽  
Scale Data

Label propagation spreads the soft labels from few labeled data to a large amount of unlabeled data according to the intrinsic graph structure. Nonetheless, most label propagation solutions work under relatively small-scale data and fail to cope with many real applications, such as social network analysis, where graphs usually have millions of nodes. In this paper, we propose a novel algorithm named \algo to deal with large-scale data. A lightweight iterative process derived from the well-known stochastic gradient descent strategy is used to reduce memory overhead and accelerate the solving process. We also give a theoretical analysis on the necessity of the warm-start technique for label propagation. Experiments show that our algorithm can handle million-scale graphs in few seconds while achieving highly competitive performance with existing algorithms.

scholarly journals Brain network topology and personality traits: a source level magnetoencephalographic study

2021 ◽  
Author(s):  
Emahnuel Troisi Lopez ◽  
Valentina Colonnello ◽  
Marianna Liparoti ◽  
Mauro Castaldi ◽  
Paolo Maria Russo ◽  
...  
Keyword(s):  
Individual Differences ◽  
Personality Traits ◽  
Caudate Nucleus ◽  
Large Scale ◽  
Brain Network ◽  
Neural Communication ◽  
Character Inventory ◽  
Left Caudate ◽  
Source Level ◽  
Large Scale Networks

Abstract Personality neuroscience is focusing on the correlation between individual differences and the efficiency of large-scale networks from the perspective of the brain as an interconnected network. A suitable technique to explore this relationship is the magnetoencephalography (MEG), but little are MEG studies aimed at investigating topological properties correlated to personality traits. By using MEG, the present study is aimed at evaluating how individual differences described in Cloninger’s psychobiological model are correlated with specific cerebral structures. Fifty healthy individuals (20 males, 30 females, mean age: 27.4 ± 4.8 years) underwent Temperament and Character Inventory examination and MEG recording during a resting state condition. High harm avoidance scores were associated with a reduced centrality of the left caudate nucleus and this negative correlation was maintained in females when we analyzed gender differences. Our data suggest that the caudate nucleus plays a key role in adaptive behavior and could be a critical node in insular salience network. The clear difference between males and females allows us to suggest that topological organization correlated to personality is highly dependent on gender. Our findings provide new insights to evaluate the mutual influences of topological and functional connectivity in neural communication efficiency and disruption as biomarkers of psychopathological traits.

scholarly journals A Study on Comparison of Network Location Efficiency of Web Application Firewall

2018 ◽  
Vol 7 (3.33) ◽  
pp. 183
Author(s):  
Sung-Ho Cho ◽  
Sung-Uk Choi ◽  
. .
Keyword(s):  
Web Services ◽  
Web Application ◽  
Large Scale ◽  
Service Providers ◽  
Web Security ◽  
Small Scale ◽  
Internet Service ◽  
Large Scale Networks ◽  
The Web ◽  
Line Type

This paper proposes a method to optimize the performance of web application firewalls according to their positions in large scale networks. Since ports for web services are always open and vulnerable in security, the introduction of web application firewalls is essential. Methods to configure web application firewalls in existing networks are largely divided into two types. There is an in-line type where a web application firewall is located between the network and the web server to be protected. This is mostly used in small scale single networks and is vulnerable to the physical obstruction of web application firewalls. The port redirection type configured with the help of peripheral network equipment such as routers or L4 switches can maintain web services even when physical obstruction of the web application firewall occurs and is suitable for large scale networks where several web services are mixed. In this study, port redirection type web application firewalls were configured in large-scale networks and there was a problem in that the performance of routers was degraded due to the IP-based VLAN when a policy was set for the ports on the routers for web security. In order to solve this problem, only those agencies and enterprises that provide web services of networks were separated and in-line type web application firewalls were configured for them. Internet service providers (ISPs) or central line-concentration agencies can apply the foregoing to configure systems for web security for unit small enterprises or small scale agencies at low costs.  

scholarly journals A Hierarchical and Abstraction-Based Blockchain Model

2019 ◽  
Vol 9 (11) ◽  
pp. 2343 ◽  
Author(s):  
Swagatika Sahoo ◽  
Akshay M. Fajge ◽  
Raju Halder ◽  
Agostino Cortesi
Keyword(s):  
Large Scale ◽  
Abstract Interpretation ◽  
Organizational Structures ◽  
Network Size ◽  
Small Scale ◽  
Time Interval ◽  
Huge Number ◽  
Large Scale Network ◽  
Regular Time ◽  
Scale Network

In the nine years since its launch, amid intense research, scalability is always a serious concern in blockchain, especially in case of large-scale network generating huge number of transaction-records. In this paper, we propose a hierarchical blockchain model characterized by: (1) each level maintains multiple local blockchain networks, (2) each local blockchain records local transactional activities, and (3) partial views (tunable w.r.t. precision) of different subsets of local blockchain-records are maintained in the blockchains at next level of the hierarchy. To meet this objective, we apply abstractions on a set of transaction-records in a regular time interval by following the Abstract Interpretation framework, which provides a tunable precision in various abstract domain and guarantees the soundness of the system. While this model suitably fits to the real-worlds organizational structures, the proposal is powerful enough to scale when large number of nodes participate in a network resulting into an enormous growth of the network-size and the number of transaction-records. We discuss experimental results on a small-scale network with three sub networks at lower-level and by abstracting the transaction-records in the abstract domain of intervals. The results are encouraging and clearly indicate the effectiveness of this approach to control exponential growth of blockchain size w.r.t. the total number of participants in the network.

scholarly journals A Topology Visualization Early Warning Distribution Algorithm for Large-Scale Network Security Incidents

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Hui He ◽  
Guotao Fan ◽  
Jianwei Ye ◽  
Weizhe Zhang
Keyword(s):  
Network Security ◽  
Network Topology ◽  
Early Warning ◽  
Early Warning System ◽  
Large Scale ◽  
Warning System ◽  
Small Scale ◽  
Large Scale Network ◽  
Scale Network ◽  
Security Incidents

It is of great significance to research the early warning system for large-scale network security incidents. It can improve the network system’s emergency response capabilities, alleviate the cyber attacks’ damage, and strengthen the system’s counterattack ability. A comprehensive early warning system is presented in this paper, which combines active measurement and anomaly detection. The key visualization algorithm and technology of the system are mainly discussed. The large-scale network system’s plane visualization is realized based on the divide and conquer thought. First, the topology of the large-scale network is divided into some small-scale networks by the MLkP/CR algorithm. Second, the sub graph plane visualization algorithm is applied to each small-scale network. Finally, the small-scale networks’ topologies are combined into a topology based on the automatic distribution algorithm of force analysis. As the algorithm transforms the large-scale network topology plane visualization problem into a series of small-scale network topology plane visualization and distribution problems, it has higher parallelism and is able to handle the display of ultra-large-scale network topology.

scholarly journals The power distribution between symmetric and anti-symmetric components of the tropical wavenumber-frequency spectrum

2021 ◽  
Author(s):  
Ofer Shamir ◽  
Chen Schwartz ◽  
Chaim I. Garfinkel ◽  
Nathan Paldor
Keyword(s):  
Frequency Spectrum ◽  
Power Distribution ◽  
Large Scale ◽  
Spectral Power ◽  
Spatial Scales ◽  
Deep Convection ◽  
Heat Fluxes ◽  
Small Scale ◽  
Ample Evidence ◽  
Parity Distribution

AbstractA yet unexplained feature of the tropical wavenumber-frequency spectrum is its parity distributions, i.e., the distribution of power between the meridionally symmetric and anti-symmetric components of the spectrum. Due to the linearity of the decomposition to symmetric and anti-symmetric components and the Fourier analysis, the total spectral power equals the sum of the power contained in each of these two components. However, the spectral power need not be evenly distributed between the two components. Satellite observations and reanalysis data provide ample evidence that the parity distribution of the tropical wavenumber-frequency spectrum is biased towards its symmetric component. Using an intermediate-complexity model of an idealized moist atmosphere, we find that the parity distribution of the tropical spectrum is nearly insensitive to large-scale forcing, including topography, ocean heat fluxes, and land-sea contrast. On the other hand, we find that a small-scale (stochastic) forcing has the capacity to affect the parity distribution at large spatial scales via an upscale (inverse) turbulent energy cascade. These results are qualitatively explained by considering the effects of triad interactions on the parity distribution. According to the proposed mechanism, any bias in the small-scale forcing, symmetric or anti-symmetric, leads to symmetric bias in the large-scale spectrum regardless of the source of variability responsible for the onset of the asymmetry. As this process is also associated with the generation of large-scale features in the Tropics by small-scale convection, the present study demonstrates that the physical process associated with deep-convection leads to a symmetric bias in the tropical spectrum.

Intermittency and Changing Stability of Oxidative Activity of DNA in Chromosomes Inside Living Cells for Medical Diagnostics

2015 ◽  
Vol 10 (04) ◽  
pp. 187-199 ◽  
Author(s):  
N. E. Galich
Keyword(s):  
Gene Networks ◽  
Large Scale ◽  
Medical Diagnostics ◽  
High Order ◽  
Oxidative Activity ◽  
Small Scale ◽  
Central Moments ◽  
Large Scale Networks ◽  
Dna Complex ◽  
Fluctuations Intensity

We analyze the experimental data on fluorescence of DNA complexes inside neutrophils in flow cytometry with nanometer spatial resolution. Fluorescence visualizes oxidative activity of DNA and unusual statistics for DNA complex of full set of chromosomes. The exponential increasing of high-order central moments for fluctuations of fluorescence intensity characterizes the existence of intermittency in oxidative activity of DNA. Intermittency depends on the scales (on rank) of DNA networks in given cells. In the large-scale networks (with the scales[Formula: see text][Formula: see text][Formula: see text]12% size of the cells), here occurs the switching to the exponential decreasing of high-order central moments for fluctuations intensity, i.e. stable oxidative activity of DNA as it is assumed for small-scale gene networks. Distributions of Hölder’s averages and high-order moments for fluctuations intensity depend on the health status and can be used for high sensitive diagnostics of health. Intermittency of large-scale correlations reflects general natural property of DNA activity and immune response on various perturbations. Intermittency reflects the mutual actions of all large-scale correlations in dense fractal networks for DNA activity and synchronization of all excitations and correlations of all chromosomes in the cells.

Sign in / Sign up

Export Citation Format

Share Document