Topology of whole-brain functional MRI networks: Improving the truncated scale-free model

2014 ◽  
Vol 405 ◽  
pp. 151-158 ◽  
Author(s):  
E. Ruiz Vargas ◽  
D.G.V. Mitchell ◽  
S.G. Greening ◽  
L.M. Wahl
Keyword(s):  
Functional Mri ◽  
Whole Brain ◽  
Scale Free ◽  
Free Model

Interactive whole brain functional MRI

NeuroImage ◽  
1996 ◽  
Vol 3 (3) ◽  
pp. S602
Author(s):  
R.W. Cox ◽  
A. Jesmanowicz ◽  
J.S. Hyde
Keyword(s):  
Functional Mri ◽  
Whole Brain

Scale-Free Networks Based on the Value of Interest

2013 ◽  
Vol 753-755 ◽  
pp. 2959-2962
Author(s):  
Jun Tao Yang ◽  
Hui Wen Deng
Keyword(s):  
Network Model ◽  
Power Law ◽  
Scale Free Network ◽  
Power Law Distribution ◽  
Scale Free ◽  
Distribution Property ◽  
Scale Free Networks ◽  
Free Model ◽  
Free Network ◽  
Interest Model

Assigning the value of interest to each node in the network, we give a scale-free network model. The value of interest is related to the fitness and the degree of the node. Experimental results show that the interest model not only has the characteristics of the BA scale-free model but also has the characteristics of fitness model, and the network has a power-law distribution property.

scholarly journals Whole-brain connectivity analysis and classification of spinocerebellar ataxia type 7 by functional MRI

2014 ◽  
Vol 1 (1) ◽  
pp. 2 ◽  
Author(s):  
Carlos R Hernandez-Castillo ◽  
Víctor Galvez ◽  
Consuelo Morgado-Valle ◽  
Juan Fernandez-Ruiz
Keyword(s):  
Functional Mri ◽  
Spinocerebellar Ataxia ◽  
Brain Connectivity ◽  
Spinocerebellar Ataxia Type ◽  
Connectivity Analysis ◽  
Whole Brain ◽  
Spinocerebellar Ataxia Type 7

scholarly journals Betweenness centrality of fractal and nonfractal scale-free model networks and tests on real networks

2007 ◽  
Vol 75 (5) ◽  
Author(s):  
Maksim Kitsak ◽  
Shlomo Havlin ◽  
Gerald Paul ◽  
Massimo Riccaboni ◽  
Fabio Pammolli ◽  
...  
Keyword(s):  
Betweenness Centrality ◽  
Scale Free ◽  
Free Model ◽  
Model Networks

scholarly journals Tumor location and reduction in functional MRI estimates of language laterality

2021 ◽  
pp. 1-11
Author(s):  
Monika M. Połczyńska ◽  
Lilian Beck ◽  
Taylor Kuhn ◽  
Christopher F. Benjamin ◽  
Timothy K. Ly ◽  
...  
Keyword(s):  
Functional Mri ◽  
Left Hemisphere ◽  
Right Hemisphere ◽  
Tumor Location ◽  
Broca’S Area ◽  
Broca's Area ◽  
Whole Brain ◽  
Language Dominance ◽  
Left Posterior ◽  
Language Laterality

OBJECTIVE Brain tumors located close to the language cortex may distort functional MRI (fMRI)–based estimates of language dominance. The nature of this distortion, and whether this is an artifact of numerous confounders, remains unknown. The authors hypothesized tumor bias based on laterality estimates independent of confounders and that the effects are the greatest for tumors proximal to Broca's area. METHODS To answer this question, the authors reviewed more than 1113 patients who underwent preoperative fMRI to match samples on 11 known confounders (tumor location, size, type, and grade; seizure history; prior neurosurgery; aphasia presence and severity; and patient age, sex, and handedness). The samples included 30 patients with left hemisphere tumors (15 anterior and 15 posterior) and 30 with right hemisphere tumors (15 anterior and 15 posterior), thus totaling 60 patients (25 women; 18 left-handed and 4 ambidextrous; mean age 47 [SD 14.1] years). Importantly, the authors matched not only patients with left and right hemisphere tumors but also those with anterior and posterior tumors. Standard fMRI laterality indices (LIs) were calculated using whole-brain and region of interest (ROI) approaches (Broca's and Wernicke's areas). RESULTS Tumors close to Broca's area in the left hemisphere decreased LIs independently of known confounders. At the whole-brain level, this appeared to reflect a decrease in LI values in patients with left anterior tumors compared with patients with right anterior tumors. ROI analysis replicated these findings. Broca's area LIs were significantly lower (p = 0.02) in patients with left anterior tumors (mean LI 0.28) when compared with patients with right anterior tumors (mean LI 0.70). Changes in Wernicke's area–based LIs did not differ as a function of the tumor hemisphere. Therefore, in patients with left anterior tumors, it is essential to assess language laterality using left posterior ROIs. In all remaining tumor groups (left posterior tumors and right hemisphere tumors), language laterality derived from the anterior language ROI was the most robust measure of language dominance. CONCLUSIONS Patients with tumors close to Broca's area showed more bilateral fMRI language maps independent of known confounders. The authors caution against the assumption that this reduced language laterality suggests no or little risk to language function following tumor resection in the left inferior frontal gyrus. Their results address how to interpret fMRI data for neurosurgical purposes, along with theoretical questions of contralesional functional compensation and disinhibition.

scholarly journals Redes Colaborativas nos Estudos Métricos de Ciência e Tecnologia │ Collaborative Networks in Metric Studies of Science and Technology

2013 ◽  
Vol 9 (1) ◽  
Author(s):  
Samile Andréa de Souza Vanz
Keyword(s):  
Network Theory ◽  
Scientific Collaboration ◽  
Preferential Attachment ◽  
Collaborative Networks ◽  
Centrality Measures ◽  
Cluster Property ◽  
Scale Free ◽  
Free Model ◽  
History Of ◽  
The Subject

Resumo A teoria de redes passou a ser muito utilizada pela Bibliometria e Cientometria porque auxilia na interpretação e no entendimento dos dados resultantes das pesquisas realizadas na área. O artigo aborda um breve histórico das redes comentando desde o modelo aleatório de Erdós e Rényi aos modelos mais atuais. Apresenta as medidas mais importantes para redes de coautoria, como densidade e medidas de centralidade. Descreve pesquisas empíricas aplicadas em redes de coautoria e suas descobertas, como a propriedade de conexão preferencial, o nível de agrupamento e o modelo sem escala. Conclui que o entendimento da teoria de redes é fundamental para o estudo do fenômeno da coautoria e que os pesquisadores interessados na temática devem ampliar o uso da mesma em suas pesquisas.Palavras-chave Redes de coautoria, colaboração científica. Abstract The network theory became widely used for Bibliometrics and Scientometrics because it helps in the understanding and interpretation of data resulting from these studies. This article covers a brief history of networks and comments from the random model of Erdós and Rényi to most current models. It presents the most important measures for co-author networks, such as density and centrality measures. It also describes applied empirical research on networks of co-authorship and its findings, as the preferential attachment, cluster property and scale free model. The article concludes that the understanding of the network theory is crucial to the study of the phenomenon of co-authorship and that researchers interested in the subject should expand the use of this theory in their research.Keywords Co-author network, scientific collaboration.

scholarly journals Cingulo-Opercular Control Network Supports Disused Motor Circuits in Standby Mode

2020 ◽  
Author(s):  
Dillan J. Newbold ◽  
Evan M. Gordon ◽  
Timothy O. Laumann ◽  
Nicole A. Seider ◽  
David F. Montez ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Spontaneous Activity ◽  
Functional Mri ◽  
Executive Control ◽  
Resting State ◽  
Control Network ◽  
Whole Brain ◽  
Motor Circuits ◽  
Standby Mode ◽  
Control Regions

AbstractWhole-brain resting-state functional MRI (rs-fMRI) during two weeks of limb constraint revealed that disused motor regions became more strongly connected to the cingulo-opercular network (CON), an executive control network that includes regions of the dorsal anterior cingulate cortex (dACC) and insula (1). Disuse-driven increases in functional connectivity (FC) were specific to the CON and somatomotor networks and did not involve any other networks, such as the salience, frontoparietal, or default mode networks. Censoring and modeling analyses showed that FC increases during casting were mediated by large, spontaneous activity pulses that appeared in the disused motor regions and CON control regions. During limb constraint, disused motor circuits appear to enter a standby mode characterized by spontaneous activity pulses and strengthened connectivity to CON executive control regions.SignificanceMany studies have examined plasticity in the primary somatosensory and motor cortex during disuse, but little is known about how disuse impacts the brain outside of primary cortical areas. We leveraged the whole-brain coverage of resting-state functional MRI (rs-fMRI) to discover that disuse drives plasticity of distant executive control regions in the cingulo-opercular network (CON). Two complementary analyses, pulse censoring and pulse addition, demonstrated that increased functional connectivity between the CON and disused motor regions was driven by large, spontaneous pulses of activity in the CON and disused motor regions. These results point to a previously unknown role for the CON in supporting motor plasticity and reveal spontaneous activity pulses as a novel mechanism for reorganizing the brain’s functional connections.

SMALL WORLD AND SCALE FREE MODEL OF TRANSMISSION OF SARS

2005 ◽  
Vol 15 (05) ◽  
pp. 1745-1755 ◽  
Author(s):  
MICHAEL SMALL ◽  
CHI K. TSE
Keyword(s):  
Hong Kong ◽  
Severe Acute Respiratory Syndrome ◽  
Infection Control ◽  
Random Number ◽  
Small World ◽  
Small World Network ◽  
Computational Simulations ◽  
Scale Free ◽  
Free Model ◽  
Analytic Expression

We model transmission of the Severe Acute Respiratory Syndrome (SARS) associated coronavirus (SARS-CoV) in Hong Kong with a complex small world network. Each node in the network is connected to its immediate neighbors and a random number of geographically isolated nodes. Transmission can only occur along these links. We find that this model exhibits dynamics very similar to those observed during the SARS outbreak in 2003. We derive an analytic expression for the rate of infection and confirm this expression with computational simulations. An immediate consequence of this quantity is that the severity of the SARS epidemic in Hong Kong in 2003 was due to ineffectual infection control in hospitals (i.e. nosocomial transmission). If all infectious individuals were isolated as rapidly as they were identified the severity of the outbreak would have been minimal.

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