scholarly journals Connective Core Structures in Cognitive Networks: the Role of Hubs

Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 961 ◽  
Author(s):  
Carlos Arruda Arruda Baltazar ◽  
Maria Isabel Barros Guinle ◽  
Cora Jirschik Caron ◽  
Edson Amaro ◽  
Birajara Soares Machado
Keyword(s):  
Complex Network ◽  
Network Topology ◽  
Information Integration ◽  
Effective Connectivity ◽  
Cognitive Networks ◽  
Invariant Structure ◽  
Network Effectiveness ◽  
Efficient Information ◽  
Behavioral States

Complex network analysis applied to the resting brain has shown that sets of highly interconnected networks with coherent activity may support a default mode of brain function within a global workspace. Perceptual processing of environmental stimuli induces architectural changes in network topology with higher specialized modules. Evidence shows that during cognitive tasks, network topology is reconfigured and information is broadcast from modular processors to a connective core, promoting efficient information integration. In this paper, we explored how the brain adapts its effective connectivity within the connective core and across behavioral states. We used complex network metrics to identify hubs and proposed a method of classification based on the effective connectivity patterns of information flow. Finally, we interpreted the role of the connective core and each type of hub on the network effectiveness. We also calculated the complexity of electroencephalography microstate sequences across different tasks. We observed that divergent hubs contribute significantly to the network effectiveness and that part of this contribution persists across behavioral states, forming an invariant structure. Moreover, we found that a large quantity of multiple types of hubs may be associated with transitions of functional networks.

scholarly journals Self-organization of in vitro neuronal assemblies drives to complex network topology

2021 ◽  
Author(s):  
Priscila Corrêa Antonello ◽  
Thomas F Varley ◽  
John Beggs ◽  
Marimélia Porcionatto ◽  
Olaf Sporns ◽  
...  
Keyword(s):  
Complex Network ◽  
Network Topology ◽  
Effective Connectivity ◽  
Small World ◽  
Self Organization ◽  
Neuronal Cultures ◽  
Highly Active ◽  
Neuronal Interactions ◽  
Effective Network

Activity-dependent self-organization plays an important role in the formation of specific and stereotyped connectivity patterns in neural circuits. By combining neuronal cultures, tools with approaches from network neuroscience and information theory, we can study how complex network topology emerges from local neuronal interactions. We constructed effective connectivity networks using a transfer entropy analysis of electrophysiological signals recorded from rat embryo dissociated hippocampal neuron cultures between 6 and 35 days in vitro to investigate how the neuronal network topology evolves during maturation. The methodology for constructing the networks considered the synapse delay and addressed the influence of firing rate and population bursts as well as spurious effects on the inference of connections. We found that the number of links in the networks grew over the course of development, shifting from a segregated to a more integrated architecture. As part of this progression, three significant aspects of complex network topology emerged. In agreement with previous in silico and in vitro studies, a small-world architecture was detected, largely due to strong clustering among neurons. Additionally, the networks developed in a modular community topology, with most modules comprising nearby neurons. Finally, highly active neurons acquired topological characteristics that made them important nodes to the network and integrators of communities. These findings leverage new insights into how neuronal effective network topology relates to neuronal assembly self-organization mechanisms.

scholarly journals The Unique Cytoarchitecture and Wiring of the Human Default Mode Network

2021 ◽  
Author(s):  
Casey Paquola ◽  
Margaret Garber ◽  
Stefan Frässle ◽  
Jessica Royer ◽  
Shahin Tavakol ◽  
...  
Keyword(s):  
Default Mode Network ◽  
Information Integration ◽  
Effective Connectivity ◽  
Structural Heterogeneity ◽  
Unique Role ◽  
Default Mode ◽  
Internal Information ◽  
Internal Sources ◽  
Magnetic Resonance Imaging Mri

It is challenging to specify the role of the default mode network (DMN) in human behaviour. Contemporary theories, based on functional magnetic resonance imaging (MRI), suggest that the DMN is insulated from the external world, which allows it to support perceptually-decoupled states and to integrate external and internal information in the construction of abstract meanings. To date, the neuronal architecture of the DMN has received relatively little attention. Understanding the cytoarchitectural composition and connectional layout of the DMN will provide novel insights into its role in brain function. We mapped cytoarchitectural variation within the DMN using a cortical type atlas and a histological model of the entire human brain. Next, we used MRI acquired in healthy young adults to explicate structural wiring and effective connectivity. We discovered profound diversity of DMN cytoarchitecture. Connectivity is organised along the most dominant cytoarchitectural axis. One side of the axis is the prominent receiver, whereas the other side remains more insulated, especially from sensory areas. The structural heterogeneity of the DMN engenders a network-level balance in communication with external and internal sources, which is distinctive, relative to other functional communities. The neuronal architecture of the DMN suggests it is a protuberance from the core cortical processing hierarchy and holds a unique role in information integration.

Carbide precipitation and chromium depletion on coherent twin boundaries in deformed 304 stainless steels

1992 ◽  
Vol 50 (2) ◽  
pp. 1216-1217
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D.J. Matlock ◽  
W.W. Fisher ◽  
P.M. Tarin ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Stainless Steels ◽  
Interfacial Free Energy ◽  
Carbide Precipitation ◽  
Twin Boundaries ◽  
Invariant Structure ◽  
Heat Treated ◽  
Constant Structure ◽  
Cr Depletion

Coherent annealing-twin boundaries are constant structure and energy interfaces with an average interfacial free energy of ∼19mJ/m2 versus ∼210 and ∼835mJ/m2 for incoherent twins and “regular” grain boundaries respectively in 304 stainless steels (SS). Due to their low energy, coherent twins form carbides about a factor of 100 slower than grain boundaries, and limited work has also shown differences in Cr-depletion (sensitization) between twin versus grain boundaries. Plastic deformation, may, however, alter the kinetics and thermodynamics of twin-sensitization which is not well understood. The objective of this work was to understand the mechanisms of carbide precipitation and Cr-depletion on coherent twin boundaries in deformed SS. The research is directed toward using this invariant structure and energy interface to understand and model the role of interfacial characteristics on deformation-induced sensitization in SS. Carbides and Cr-depletion were examined on a 20%-strain, 0.051%C-304SS, heat treated to 625°C-4.5h, as described elsewhere.

scholarly journals Role of Matrix Gla Protein in the Complex Network of Coronary Artery Disease: A Comprehensive Review

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 737
Author(s):  
Marko Kumric ◽  
Josip A. Borovac ◽  
Tina Ticinovic Kurir ◽  
Dinko Martinovic ◽  
Ivan Frka Separovic ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Complex Network ◽  
Vascular Calcification ◽  
Vitamin K ◽  
Clinical Decision Making ◽  
Large Body ◽  
Matrix Gla Protein ◽  
Artery Disease

Coronary artery disease (CAD) is widely recognized as one of the most important clinical entities. In recent years, a large body of accumulated data suggest that coronary artery calcification, a process highly prevalent in patients with CAD, occurs via well-organized biologic processes, rather than passively, as previously regarded. Matrix Gla protein (MGP), a vitamin K-dependent protein, emerged as an important inhibitor of both intimal and medial vascular calcification. The functionality of MGP hinges on two post-translational modifications: phosphorylation and carboxylation. Depending on the above-noted modifications, various species of MGP may exist in circulation, each with their respective level of functionality. Emerging data suggest that dysfunctional species of MGP, markedly, dephosphorylated-uncarboxylated MGP, might find its application as biomarkers of microvascular health, and assist in clinical decision making with regard to initiation of vitamin K supplementation. Hence, in this review we summarized the current knowledge with respect to the role of MGP in the complex network of vascular calcification with concurrent inferences to CAD. In addition, we discussed the effects of warfarin use on MGP functionality, with concomitant implications to coronary plaque stability.

scholarly journals Loss of Calretinin in L5a impairs the formation of the barrel cortex leading to abnormal whisker-mediated behaviors

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Mingzhao Su ◽  
Junhua Liu ◽  
Baocong Yu ◽  
Kaixing Zhou ◽  
Congli Sun ◽  
...  
Keyword(s):  
Information Integration ◽  
Pyramidal Neurons ◽  
Barrel Cortex ◽  
Sensory Information ◽  
Membrane Excitability ◽  
Novelty Preference ◽  
Layer 4 ◽  
Dendritic Complexity ◽  
Cortex System

AbstractThe rodent whisker-barrel cortex system has been established as an ideal model for studying sensory information integration. The barrel cortex consists of barrel and septa columns that receive information input from the lemniscal and paralemniscal pathways, respectively. Layer 5a is involved in both barrel and septa circuits and play a key role in information integration. However, the role of layer 5a in the development of the barrel cortex remains unclear. Previously, we found that calretinin is dynamically expressed in layer 5a. In this study, we analyzed calretinin KO mice and found that the dendritic complexity and length of layer 5a pyramidal neurons were significantly decreased after calretinin ablation. The membrane excitability and excitatory synaptic transmission of layer 5a neurons were increased. Consequently, the organization of the barrels was impaired. Moreover, layer 4 spiny stellate cells were not able to properly gather, leading to abnormal formation of barrel walls as the ratio of barrel/septum size obviously decreased. Calretinin KO mice exhibited deficits in exploratory and whisker-associated tactile behaviors as well as social novelty preference. Our study expands our knowledge of layer 5a pyramidal neurons in the formation of barrel walls and deepens the understanding of the development of the whisker-barrel cortex system.

scholarly journals On Synchronizing Coupled Retinogeniculocortical Pathways: A Toy Model

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
B. L. Mayer ◽  
L. H. A. Monteiro
Keyword(s):  
Neural Network ◽  
Visual Cortex ◽  
Corpus Callosum ◽  
Neuronal Activity ◽  
Network Topology ◽  
Cerebral Hemisphere ◽  
State Transition ◽  
Regular Lattice ◽  
Visual Cortices

A Newman-Watts graph is formed by including random links in a regular lattice. Here, the emergence of synchronization in coupled Newman-Watts graphs is studied. The whole neural network is considered as a toy model of mammalian visual pathways. It is composed by four coupled graphs, in which a coupled pair represents the lateral geniculate nucleus and the visual cortex of a cerebral hemisphere. The hemispheres communicate with each other through a coupling between the graphs representing the visual cortices. This coupling makes the role of the corpus callosum. The state transition of neurons, supposed to be the nodes of the graphs, occurs in discrete time and it follows a set of deterministic rules. From periodic stimuli coming from the retina, the neuronal activity of the whole network is numerically computed. The goal is to find out how the values of the parameters related to the network topology affect the synchronization among the four graphs.

scholarly journals Loss of Calretinin in L5a Impairs the Formation of the Barrel Cortex Leading to Abnormal Behaviors

2021 ◽  
Author(s):  
Mingzhao Su ◽  
Junhua Liu ◽  
Baocong Yu ◽  
Kaixing Zhou ◽  
Congli Sun ◽  
...  
Keyword(s):  
Information Integration ◽  
Pyramidal Neurons ◽  
Barrel Cortex ◽  
Sensory Information ◽  
Membrane Excitability ◽  
Novelty Preference ◽  
Abnormal Behaviors ◽  
Dendritic Complexity ◽  
Cortex System

Abstract The rodent whisker-barrel cortex system has been established as an ideal model for studying sensory information integration. The barrel cortex consists of barrel and septa columns that receive information input from the lemniscal and paralemniscal pathways, respectively. L5a is involved in both barrel and septa circuits and play a key role in information integration. However, the role of L5a in the development of the barrel cortex remains unclear. Previously, we found that Calretinin is dynamically expressed in L5a. In this study, we analyzed Cr KO mice and found that the dendritic complexity and length of L5a pyramidal neurons were significantly decreased after Cr ablation. The membrane excitability and excitatory synaptic transmission of L5a neurons were increased. Consequently, the organization of the barrels was impaired. Moreover, L4 spiny stellate cells were not able to properly gather, leading to abnormal formation of barrel walls as the ratio of barrel/septum size obviously decreased. Cr KO mice exhibited deficits in exploratory and whisker-associated tactile behaviors as well as social novelty preference. Our study expands our knowledge of L5a pyramidal neurons in the formation of barrel walls and deepens the understanding of the development of the whisker-barrel cortex system.

scholarly journals Software Engineering and New Emerging Technologies

Economics ◽  
2015 ◽  
pp. 1541-1563
Author(s):  
Sergio Ricardo Mazini
Keyword(s):  
Software Engineering ◽  
Information Integration ◽  
Research Method ◽  
Emerging Technologies ◽  
Sales Force ◽  
Mobile Technologies ◽  
Sales Force Automation ◽  
Industrial Companies

This chapter presents an approach to the role of software engineering in developing solutions for new mobile technologies, like tablets. It discusses the importance of the new standards brought by emerging technologies such as engineering and how software must adapt to this new reality in order to identify the needs of data, information, integration, shares, and other issues that will contribute to the life cycle of these solutions. The chapter also discusses the contribution of users in the development process and improve these solutions. The research method is the case study conducted in industrial companies that use a digital catalog solution and sales force automation for tablets. This chapter presents a new approach based on commercial tablets which is supported by a platform of software and services called commercially Nimiam (www.nimiam.com.br).

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