scholarly journals Structural and functional properties of a probabilistic model of neuronal connectivity in a simple locomotor network

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Andrea Ferrario ◽  
Robert Merrison-Hort ◽  
Stephen R Soffe ◽  
Roman Borisyuk
Keyword(s):  
Probabilistic Model ◽  
Structural Characteristics ◽  
Brain Connectivity ◽  
Rhythmic Activity ◽  
Neuronal Dynamics ◽  
Structural And Functional Properties ◽  
Network Properties ◽  
Functional Features ◽  
Experimental Findings ◽  
Spiking Model

Although, in most animals, brain connectivity varies between individuals, behaviour is often similar across a species. What fundamental structural properties are shared across individual networks that define this behaviour? We describe a probabilistic model of connectivity in the hatchling Xenopus tadpole spinal cord which, when combined with a spiking model, reliably produces rhythmic activity corresponding to swimming. The probabilistic model allows calculation of structural characteristics that reflect common network properties, independent of individual network realisations. We use the structural characteristics to study examples of neuronal dynamics, in the complete network and various sub-networks, and this allows us to explain the basis for key experimental findings, and make predictions for experiments. We also study how structural and functional features differ between detailed anatomical connectomes and those generated by our new, simpler, model (meta-model).

scholarly journals Resting-state brain network topological properties and the correlation with neuropsychological assessment in adolescent narcolepsy

SLEEP ◽  
2020 ◽  
Vol 43 (8) ◽  
Author(s):  
Xiao Fulong ◽  
Spruyt Karen ◽  
Lu Chao ◽  
Zhao Dianjiang ◽  
Zhang Jun ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Neuropsychological Assessment ◽  
Resting State ◽  
Brain Connectivity ◽  
Small World ◽  
Theoretical Method ◽  
Brain Network ◽  
Topological Properties ◽  
Depressive Feelings ◽  
Network Properties

Abstract Study Objectives To evaluate functional connectivity and topological properties of brain networks, and to investigate the association between brain topological properties and neuropsychiatric behaviors in adolescent narcolepsy. Methods Resting-state functional magnetic resonance imaging (fMRI) and neuropsychological assessment were applied in 26 adolescent narcolepsy patients and 30 healthy controls. fMRI data were analyzed in three ways: group independent component analysis and a graph theoretical method were applied to evaluate topological properties within the whole brain. Lastly, network-based statistics was utilized for group comparisons in region-to-region connectivity. The relationship between topological properties and neuropsychiatric behaviors was analyzed with correlation analyses. Results In addition to sleepiness, depressive symptoms and impulsivity were detected in adolescent narcolepsy. In adolescent narcolepsy, functional connectivity was decreased between regions of the limbic system and the default mode network (DMN), and increased in the visual network. Adolescent narcolepsy patients exhibited disrupted small-world network properties. Regional alterations in the caudate nucleus (CAU) and posterior cingulate gyrus were associated with subjective sleepiness and regional alterations in the CAU and inferior occipital gyrus were associated with impulsiveness. Remodeling within the salience network and the DMN was associated with sleepiness, depressive feelings, and impulsive behaviors in narcolepsy. Conclusions Alterations in brain connectivity and regional topological properties in narcoleptic adolescents were associated with their sleepiness, depressive feelings, and impulsive behaviors.

scholarly journals Heparan Sulfate Proteoglycan Signaling in Tumor Microenvironment

2020 ◽  
Vol 21 (18) ◽  
pp. 6588 ◽  
Author(s):  
Valeria De Pasquale ◽  
Luigi Michele Pavone
Keyword(s):  
Tumor Microenvironment ◽  
Heparan Sulfate ◽  
Cancer Progression ◽  
Structural Characteristics ◽  
Tumor Type ◽  
Wide Range ◽  
Functional Features ◽  
Complex Structural ◽  
Tumor Cell Behavior ◽  
Living Organisms

In the last few decades, heparan sulfate (HS) proteoglycans (HSPGs) have been an intriguing subject of study for their complex structural characteristics, their finely regulated biosynthetic machinery, and the wide range of functions they perform in living organisms from development to adulthood. From these studies, key roles of HSPGs in tumor initiation and progression have emerged, so that they are currently being explored as potential biomarkers and therapeutic targets for cancers. The multifaceted nature of HSPG structure/activity translates in their capacity to act either as inhibitors or promoters of tumor growth and invasion depending on the tumor type. Deregulation of HSPGs resulting in malignancy may be due to either their abnormal expression levels or changes in their structure and functions as a result of the altered activity of their biosynthetic or remodeling enzymes. Indeed, in the tumor microenvironment, HSPGs undergo structural alterations, through the shedding of proteoglycan ectodomain from the cell surface or the fragmentation and/or desulfation of HS chains, affecting HSPG function with significant impact on the molecular interactions between cancer cells and their microenvironment, and tumor cell behavior. Here, we overview the structural and functional features of HSPGs and their signaling in the tumor environment which contributes to tumorigenesis and cancer progression.

Fatigue Crack Growth Prediction Under Random Peaks and Sequence Loading

1989 ◽  
Vol 111 (4) ◽  
pp. 338-344 ◽  
Author(s):  
H. Alawi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Probabilistic Model ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Constant Amplitude ◽  
Random Loads ◽  
Prediction Techniques ◽  
Experimental Findings

Fatigue crack growth under random amplitude and sequence loading with peaks following the Rayleigh probability density function is simulated using the probabilistic model. Another attempt at fatigue life prediction under the above loads is made by converting random loads in to equivalent constant amplitude. Prediction results are compared with experimental findings. Empirical data for fatigue crack growth under random loads at different frequencies are compared with the results of prediction using the above techniques. Experimental results of three steels are used in this study to compare with the findings of the above prediction techniques. These steels are AISI 1018, AISI 4340 and stainless pH 17-7. It is seen that the probabilistic model produces reliable results. It conservatively predicts fatigue crack growth when no delay mechanism to retard crack growth is introduced.

scholarly journals Brain network dynamics codify heterogeneity in seizure propagation

2021 ◽  
Author(s):  
Nuttida Rungratsameetaweemana ◽  
Claudia Lainscsek ◽  
Sydney S Cash ◽  
Javier O Garcia ◽  
Terrence J Sejnowski ◽  
...  
Keyword(s):  
Neurological Disorders ◽  
Brain Connectivity ◽  
Clinical Manifestations ◽  
Treatment Strategies ◽  
Brain Network ◽  
Functional Brain ◽  
Graph Theoretical Approach ◽  
Network Properties ◽  
Adaptive Cognition ◽  
And Behavior

Dynamic functional brain connectivity facilitates adaptive cognition and behavior. Abnormal alterations within such connectivity could result in disrupted functions observed across various neurological conditions. As one of the most common neurological disorders, epilepsy is defined by the seemingly random occurrence of spontaneous seizures. A central but unresolved question concerns the mechanisms by which extraordinarily diverse dynamics of seizures emerge. Here, we apply a graph-theoretical approach to assess dynamic reconfigurations in the functional brain connectivity before, during, and after seizures that display heterogeneous propagation patterns despite sharing similar origins. We demonstrate unique reconfigurations in globally-defined network properties preceding seizure onset that predict propagation patterns of impending seizures, and in locally-defined network properties that differentiate post-onset dynamics. These results characterize quantitative network features underlying the heterogeneity of seizure dynamics and the accompanying clinical manifestations. Decoding these network properties could improve personalized preventative treatment strategies for epilepsy as well as other neurological disorders.

scholarly journals Brain connectivity-based prediction of real-life creativity is mediated by semantic memory structure

2021 ◽  
Author(s):  
Marcela Ovando-Tellez ◽  
Yoed Nissan Kenett ◽  
Mathias Benedek ◽  
Matthieu Bernard ◽  
Joan Belo ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Semantic Memory ◽  
Brain Connectivity ◽  
Real Life ◽  
Semantic Relatedness ◽  
Predictive Modelling ◽  
Judgment Task ◽  
Creative Cognition ◽  
Network Properties ◽  
Brain Functional Connectivity

Creative cognition relies on the ability to form remote associations between concepts, which allows to generate novel ideas or solve new problems. Such an ability is related to the organisation of semantic memory; yet whether real-life creative behaviour relies on semantic memory organisation and its neural substrates remains unclear. Therefore, this study explored associations between brain functional connectivity patterns, network properties of individual semantic memory, and real-life creativity. We acquired multi-echo functional MRI data while participants underwent a semantic relatedness judgment task. These ratings were used to estimate their individual semantic memory networks, whose properties significantly predicted their real-life creativity. Using a connectome-based predictive modelling approach, we identified patterns of task-based functional connectivity that predicted creativity-related semantic memory network properties. Furthermore, these properties mediated the relationship between functional connectivity and real-life creativity. These results provide new insights into how brain connectivity supports the associative mechanisms of creativity.

Functional and Structural Characteristics of Metallic Foams Produced by the SlipReactionFoamSintering (SRFS)-Process

2005 ◽  
Vol 492-493 ◽  
pp. 39-46 ◽  
Author(s):  
S. Angel ◽  
Wolfgang Bleck ◽  
S. Harksen ◽  
P.-F. Scholz
Keyword(s):  
Heat Exchangers ◽  
Alloy Powder ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Metallic Foams ◽  
Open Cell ◽  
Structural And Functional Properties ◽  
Wide Range ◽  
High Alloyed Steel ◽  
Highly Porous

Highly porous open- cell materials on the base of various metals and alloys are of increasing interest as they combine structural and functional properties. There is a wide range of possible applications for such materials, e.g. as heat exchangers, filters or catalysts. A new and promising method to produce open- cell metallic foams on base of iron powder, low and high alloyed steel powders as well as nickel alloy powder is the SlipReactionFoamSintering (SRFS)- process. In comparison to other production processes of metallic foams, the SRFS- process provides several advantages: foaming at room temperature, allowing a very good process control by various parameters, foams of a great variety of metals are possible and a broad spectrum of properties is achievable.

scholarly journals STRUCTURAL CHARACTERISTICS OF HEPATOCYTES IN WHITE RATS

2021 ◽  
Vol 21 (2) ◽  
pp. 146-150
Author(s):  
Н.M. Mustafina
Keyword(s):  
Liver Tissue ◽  
Structural Characteristics ◽  
Complex Structure ◽  
Liver Cells ◽  
Morphological Data ◽  
Ethical Framework ◽  
Control Group ◽  
Thin Sections ◽  
White Rats ◽  
Functional Features

At present the liver is known as a polyfunctional organ of a highly complex structure, and more than 80% of the liver cell population is hepatocytes, organ-specific cells involved in the absorption, synthesis and accumulation of various substances subsequently secreted into the blood or bile. The aim of the study is to obtain at the light-optical level a set of morphological data characterizing the structural features of hepatocytes in white rats. The study was carried out on 10 outbred white rats of both sexes weighing 204 ± 0.67 g. All studies were carried out within the bioethical and ethical framework when using experimental animals. Traditional paraffin blocks and semi-thin sections were made from liver preparations and then studied using a light microscope. The studies have demonstrated that in the liver tissue of intact white rats, hepatocytes predominate in quantitative terms. The dimensional characteristics of the latter are quite variable and range within transverse size from 15.38 - 19.41 μm, longitudinal size from 21.98 - 26.46 μm, and the average area of ​​hepatocytes, respectively varies from 432.50 ± 40.93 μm2. The average diameter of the nuclei is 7.61 ± 0.25 μm, and the area of ​​the nucleus is 45.46 ± 3.06 μm2. Considering the findings, the arithmetic mean of the area of ​​the cytoplasm is 387.03 ± 41.03 μm2, and the nuclear – cytoplasmic ratio of hepatocytes, respectively, averages 0.119 ± 0.01. The overwhelming number of hepatocytes has one nucleus, and the relative number of such cells makes up 79.41%. Accordingly, to 20.59% of hepatocytes contain two nuclei; tri-nuclear cells have not been found. The study has revealed that the liver tissue of the white rats of the control group is represented mainly by hepatocytes with the moderate number of evenly distributed glycogen granules, occupying mainly the intermediate parts of the hepatic lobules. The study of semi-thin sections has shown the polymorphism of the of hepatocytes, among which, on the basis of tinctorial properties of the nucleus and cytoplasm, four types can be distinguished, while hepatocytes with moderate basophilia of the cytoplasm and a dark nucleus predominate quantitatively. It is suggested that the morphological picture of hepatocytes on classical histological preparations is primarily due to the amount of glycogen in the cytoplasm, while on semi-thin sections, other functional features of individual liver cells are observed including the intensity of bile production, secretion of proteins, fats and others substances. Thus, the features of the structure of various types of hepatocytes must be considered in the differential diagnosis of the functional state of liver cells.

scholarly journals Predicting Empathy from Resting Brain Connectivity

2019 ◽  
Author(s):  
Leonardo Christov-Moore ◽  
Nicco Reggente ◽  
Pamela K. Douglas ◽  
Jamie D. Feusner ◽  
Marco Iacoboni
Keyword(s):  
Sex Differences ◽  
Visual System ◽  
Brain Connectivity ◽  
Network Connectivity ◽  
Task Demands ◽  
Empathic Concern ◽  
Control Networks ◽  
Biological Sex ◽  
Network Properties ◽  
And Control

AbstractRecent studies suggest that individual differences in empathic concern may be mediated by continuous interactions between self-other resonance and cognitive control networks. To test this hypothesis, we used machine learning to examine whether resting fMRI connectivity (i.e. the degree of synchronous BOLD activity across multiple cortical areas in the absence of task demands) of resonance and control networks could predict trait empathy (n=58). Indeed, resonance and control networks’ interconnectivity predicted empathic concern. Empathic concern was also predicted by connectivity within the somatomotor network. In light of numerous reported sex differences in empathy, we controlled for biological sex and also studied separately what aspect of these features could predict participants’ sex. Sex was best predicted by the interconnectivity of the visual system with the resonance, somatomotor, and cingulo-opercular network, as well as the somatomotor-control network connectivity. These findings confirm that variation in empathic responses to others reflects characteristic network properties detectable regardless of task demands. Furthermore, network properties of the visual system may be a locus of sex differences previously unaccounted for in empathy research. Finally, these findings suggest that it may be possible to assess empathic predispositions in individuals without needing to perform conventional empathy assessments.

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