scholarly journals Is removal of weak connections necessary for graph-theoretical analysis of dense weighted structural connectomes?

2019 ◽  
Author(s):  
Oren Civier ◽  
Robert Elton Smith ◽  
Chun-Hung Yeh ◽  
Alan Connelly ◽  
Fernando Calamante
Keyword(s):  
Statistical Analysis ◽  
Theoretical Analysis ◽  
Threshold Level ◽  
Brain Organization ◽  
Graph Theoretical Analysis ◽  
Human Connectome Project ◽  
Significant Difference ◽  
Topological Measures ◽  
Using Data ◽  
The Stability

ABSTRACTRecent advances in diffusion MRI tractography permit the generation of dense weighted structural connectomes that offer greater insight into brain organization. However, these efforts are hampered by the lack of consensus on how to extract topological measures from the resulting graphs. Here we evaluate the common practice of removing the graphs’ weak connections, which is primarily intended to eliminate spurious connections and emphasize strong connections. Because this processing step requires arbitrary or heuristic-based choices (e.g., setting a threshold level below which connections are removed), and such choices might complicate statistical analysis and inter-study comparisons, in this work we test whether removing weak connections is indeed necessary. To this end, we systematically evaluated the effect of removing weak connections on a range of popular graph-theoretical metrics. Specifically, we investigated if (and at what extent) removal of weak connections introduces a statistically significant difference between two otherwise equal groups of healthy subjects when only applied to one of the groups. Using data from the Human Connectome Project, we found that removal of weak connections had no statistical effect even when removing the weakest~70-90% connections. Removing yet a larger extent of weak connections, thus reducing connectivity density even further, did produce a predictably significant effect. However, metric values became sensitive to the exact connectivity density, which has ramifications regarding the stability of the statistical analysis. This pattern persisted whether connections were removed by connection strength threshold or connectivity density, and for connectomes generated using parcellations at different resolutions. Finally, we showed that the same pattern also applies for data from a clinical-grade MRI scanner. In conclusion, our analysis revealed that removing weak connections is not necessary for graph-theoretical analysis of dense weighted connectomes. Because removal of weak connections provides no practical utility to offset the undesirable requirement for arbitrary or heuristic-based choices, we recommend that this step is avoided in future studies.Declarations of interestnone.

scholarly journals Mapping Brain Microstructure and Network Alterations in Depressive Patients with Suicide Attempts Using Generalized Q-Sampling MRI

2021 ◽  
Vol 11 (3) ◽  
pp. 174
Author(s):  
Vincent Chin-Hung Chen ◽  
Chun-Ju Kao ◽  
Yuan-Hsiung Tsai ◽  
Roger S. McIntyre ◽  
Jun-Cheng Weng
Keyword(s):  
Statistical Analysis ◽  
White Matter ◽  
Theoretical Analysis ◽  
Depressive Disorder ◽  
Suicide Attempts ◽  
Healthy Controls ◽  
Graph Theoretical Analysis ◽  
Depressed Patients ◽  
Structural Differences ◽  
History Of

Depressive disorder is one of the leading causes of disability worldwide, with a high prevalence and chronic course. Depressive disorder carries an increased risk of suicide. Alterations in brain structure and networks may play an important role in suicidality among depressed patients. Diffusion magnetic resonance imaging (MRI) is a noninvasive method to map white-matter fiber orientations and provide quantitative parameters. This study investigated the neurological structural differences and network alterations in depressed patients with suicide attempts by using generalized q-sampling imaging (GQI). Our study recruited 155 participants and assigned them into three groups: 44 depressed patients with a history of suicide attempts (SA), 56 depressed patients without a history of suicide attempts (D) and 55 healthy controls (HC). We used the GQI to analyze the generalized fractional anisotropy (GFA) and normalized quantitative anisotropy (NQA) values in voxel-based statistical analysis, topological parameters in graph theoretical analysis and subnetwork connectivity in network-based statistical analysis. GFA indicates the measurement of neural anisotropy and represents white-matter integrity; NQA indicates the amount of anisotropic spins that diffuse along fiber orientations and represents white-matter compactness. In the voxel-based statistical analysis, we found lower GFA and NQA values in the SA group than in the D and HC groups and lower GFA and NQA values in the D group than in the HC group. In the graph theoretical analysis, the SA group demonstrated higher local segregation and lower global integration among the three groups. In the network-based statistical analysis, the SA group showed stronger subnetwork connections in the frontal and parietal lobes, and the D group showed stronger subnetwork connections in the parietal lobe than the HC group. Alternations were found in the structural differences and network measurements in healthy controls and depressed patients with and without a history of suicide attempt.

scholarly journals Assessment of Disrupted Brain Structural Connectome in Depressive Patients With Suicidal Ideation Using Generalized Q-Sampling MRI

2021 ◽  
Vol 15 ◽  
Author(s):  
Vincent Chin-Hung Chen ◽  
Chun-Ju Kao ◽  
Yuan-Hsiung Tsai ◽  
Man Teng Cheok ◽  
Roger S. McIntyre ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Suicidal Ideation ◽  
Theoretical Analysis ◽  
Brain Structures ◽  
Healthy Controls ◽  
Global Integration ◽  
Structural Variations ◽  
Topological Parameters ◽  
Graph Theoretical Analysis ◽  
Depressed Patients

Suicide is one of the leading causes of mortality worldwide. Various factors could lead to suicidal ideation (SI), while depression is the predominant cause among all mental disorders. Studies have shown that alterations in brain structures and networks may be highly associated with suicidality. This study investigated both neurological structural variations and network alterations in depressed patients with suicidal ideation by using generalized q-sampling imaging (GQI) and Graph Theoretical Analysis (GTA). This study recruited 155 participants and divided them into three groups: 44 depressed patients with suicidal ideation (SI+; 20 males and 24 females with mean age = 42, SD = 12), 56 depressed patients without suicidal ideation (Depressed; 24 males and 32 females with mean age = 45, SD = 11) and 55 healthy controls (HC; nine males and 46 females with mean age = 39, SD = 11). Both the generalized fractional anisotropy (GFA) and normalized quantitative anisotropy (NQA) values were evaluated in a voxel-based statistical analysis by GQI. We analyzed different topological parameters in the graph theoretical analysis and the subnetwork interconnections in the Network-based Statistical (NBS) analysis. In the voxel-based statistical analysis, both the GFA and NQA values in the SI+ group were generally lower than those in the Depressed and HC groups in the corpus callosum and cingulate gyrus. Furthermore, we found that the SI+ group demonstrated higher global integration and lower local segregation among the three groups of participants. In the network-based statistical analysis, we discovered that the SI+ group had stronger connections of subnetworks in the frontal lobe than the HC group. We found significant structural differences in depressed patients with suicidal ideation compared to depressed patients without suicidal ideation and healthy controls and we also found several network alterations among these groups of participants, which indicated that white matter integrity and network alterations are associated with patients with depression as well as suicidal ideation.

scholarly journals Topological Characteristics Associated with Intraoperative Stimulation Related Epilepsy of Glioma Patients: A DTI Network Study

2021 ◽  
Author(s):  
Jianing Yang ◽  
Chunyao Zhou ◽  
Yuchao Liang ◽  
Yinyan Wang ◽  
Lei Wang
Keyword(s):  
Theoretical Analysis ◽  
Life Quality ◽  
Lower Efficiency ◽  
Graph Theoretical Analysis ◽  
Gender And Education ◽  
Significant Difference ◽  
Presurgical Assessment ◽  
Topological Characteristics ◽  
Intraoperative Electrical Stimulation ◽  
Centrality Analysis

Abstract Purpose Awake craniotomy with intraoperative stimulation has been utilized in glioma surgical resection to preserve life quality. While 5-20% of cases may occur epilepsy during the procedure which leads to severe consequences. The study aimed to discussing the mechanism of intraoperative stimulation-related epilepsy (ISE) with DTI based graph theoretical analysis.Methods 20 patients with motor-area glioma were enrolled and divided into 2 groups (Ep and nEp) according to whether there was ISE. Additionally, a group of 10 healthy participants matched by age, gender and education year were also involved. All participants underwent T1, T2 and DTI. Graph theoretical analysis was applied to reveal topological characteristics of the white matter networks. Results Three connections were found to be significantly lower in at least one weighting in Ep group. They are the connection between A1/2/3truL and A4ulL, A1/2/3truR and A4tR, and A6mL and A6mR. Global efficiency was found to be significantly decreased while the shortest path length increased in Ep group in at least one weighting. Ten nodes exhibited significant difference in the nodal efficiency and degree centrality analysis. The nodes A6mL and A6mR showed markable decrease in total four weightings in Ep group.Conclusion The hub nodes A6mL and A6mR, get disconnected in the patients with ISE, causing subsequent lower efficiency of global and regional network. The findings provide basis for presurgical assessment of ISE, for that caution should be taken when it involves hub nodes during intraoperative electrical stimulation.

scholarly journals Evaluation of the Effects of Different Surface Configurations on Stability of Miniscrews

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Tolga Topcuoglu ◽  
A. Altuğ Bicakci ◽  
M. Cihat Avunduk ◽  
Z. Deniz Sahin Inan
Keyword(s):  
Statistical Analysis ◽  
The Other ◽  
Immediate Loading ◽  
Screw Design ◽  
Force Application ◽  
Group I ◽  
Significant Difference ◽  
The Stability ◽  
Positive Effect ◽  
Surrounding Bone

Introduction. The aim of this study was to analyze the effects of screw design and force application on the stability of miniscrews, using RTT, SEM, and histomorphometric analyses.Materials and Methods. Eighty cylindrical, self-drilling, and Ti6Al4V alloy miniscrews (1,6 × 6 mm) were used. Four mini-screws were inserted in fibulas of each rabbit, and 115 Gof force was immediately applied. Four miniscrews were inserted in the other fibula, on which no force was applied. Eight weeks after insertion, osseointegration between miniscrew and the surrounding bone was evaluated by the histomorphometric analyses, SEM, and RTT. Kruskal-Wallis and the pairedt-tests were used for statistical analysis.Results. Values obtained from Group I were significantly higher than those of the other loaded groups (). There were no differences in RTT scores among Groups II, III, and IV. Similar findings were also observed for unloaded mini-screws. There was no significant difference between Groups I and , while the differences between loaded and unloaded controls for each miniscrew were statistically significant.Conclusions. Immediate loading of miniscrews does not impair screw stability. Also, the diameter of miniscrew and more frequent thread pitches have a positive effect on stability; however, length of miniscrews does not have a significant effect on the stability.

scholarly journals Functional connectome analyses reveal a highly optimized human olfactory network

2019 ◽  
Author(s):  
T. Campbell Arnold ◽  
Yuqi You ◽  
Mingzhou Ding ◽  
Xi-Nian Zuo ◽  
Ivan de Araujo ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Olfactory System ◽  
Topological Analysis ◽  
Anterior Insula ◽  
Connectivity Matrix ◽  
Functional Neuroanatomy ◽  
Graph Theoretical Analysis ◽  
Human Connectome Project ◽  
Local Circuits ◽  
Local Segregation

AbstractThe olfactory system is uniquely heterogeneous, performing multifaceted functions (beyond basic sensory processing) across diverse, widely distributed neural substrates. While knowledge of human olfaction continues to grow, it remains unclear how the olfactory network is organized to serve this unique set of functions. Leveraging a large and high-quality resting-state functional magnetic resonance imaging (rs-fMRI) dataset of nearly 900 participants from the Human Connectome Project (HCP), we identified a human olfactory network encompassing cortical and subcortical regions across the temporal and frontal lobes. Highlighting its reliability and generalizability, the connectivity matrix of this olfactory network mapped closely onto that extracted from an independent rs-fMRI dataset. Graph theoretical analysis further explicated the organizational principles of the network. The olfactory network exhibits a functionally advantageous modular composition of three (i.e., the sensory, limbic, and frontal) subnetworks and demonstrates strong small-world properties, high in both global integration and local segregation (i.e., circuit specialization). This network organization thus ensures the segregation of local circuits, which are nonetheless integrated via connecting hubs (i.e., amygdala and anterior insula), thereby enabling the specialized, yet integrative, functions of olfaction. In particular, the degree of local segregation positively predicted olfactory discrimination performance in the independent sample. In sum, an olfactory functional network has been identified through the large HCP dataset, affording a representative template of the human olfactory functional neuroanatomy. Importantly, the topological analysis of the olfactory network provides network-level insights into the remarkable functional specialization and spatial segregation of the olfactory system.Significance StatementOlfaction is an intriguing multifunctional system, playing key roles in regulating emotions, autonomic tone, and feeding, beyond basic sensory perception. However, it is unclear how the neuroanatomy of olfaction is organized in humans to subserve these functions. Functional connectivity analysis of the HCP dataset combined with graph theoretical analysis revealed an optimized large-scale network consisting of three subnetworks—the sensory, limbic, and frontal subnetworks. Distributed across frontal and temporal lobes in well segregated fashion, these olfactory structures are also highly integrated, linked through hub nodes of the amygdala and anterior insula. Our independent dataset replicated the HCP-derived olfactory network and, importantly, highlighted a direct association between the degree of network segregation and olfactory perception.

Graph theoretical analysis of tau burden and the functional connectome in Alzheimers disease

2019 ◽  
Author(s):  
A Weller ◽  
GN Bischof ◽  
P Schlüter ◽  
N Richter ◽  
J Kukolja ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Alzheimers Disease ◽  
Graph Theoretical Analysis ◽  
Functional Connectome

ESTIMATION OF TECHNICAL, SPECIALIZED AND ECONOMIC EFFICIENCY OF CULTIVATED POTATO VARIETIES USING DATA ENVELOPE ANALYSIS METHOD (DEA) IN IRAQ FOR SPRING LUG 2018

2020 ◽  
pp. 119-131
Keyword(s):  
Technical Efficiency ◽  
Economic Efficiency ◽  
Potato Crop ◽  
Economic Status ◽  
Analysis Method ◽  
Envelope Analysis ◽  
Variable Capacity ◽  
Data Envelope Analysis ◽  
Using Data ◽  
The Stability

Research highlights the importance of potato crop, which occupies a prominent food and economic status in food security besides rice, wheat and corn at the local and global level. Despite the expansion of the cultivation of potato crop in Iraq in general and Ameriyah district in particular However, potato productivity remains substandard, this may be due to a lack of knowledge of the most efficient varieties and not to use productive resources at the levels at which technical, specialized and economic efficiency is achieved. Therefore, the aim of the research is to determine the technical, specialized and economic efficiency according to the cultivated seed category. The data envelope analysis (DEA) method was used to estimate technical, specialized and economic efficiency, assuming constant and variable capacity returns. As a result of the study, the Safrana variety achieved the highest average technical efficiency according to the stability of the yield and capacity efficiency in addition to achieving the highest average specialized and economic efficiency, The Lapadia variety achieved the highest average technical efficiency, assuming that capacity returns have changed. Therefore, we recommend the adoption of items that achieve higher efficiency and the need to redistribute the elements of production better and Achieving the optimum levels at which technical, specialized and economic efficiency is achieved and saving what has been wasted.

scholarly journals The Role of Employment Protection during an Exogenous Shock to an Economy

2011 ◽  
Vol 11 (2) ◽  
pp. 1850225 ◽  
Author(s):  
Miki Malul ◽  
Mosi Rosenboim ◽  
Tal Shavit ◽  
Shlomo Yedidia Tarba
Keyword(s):  
Economic Crisis ◽  
Employment Protection ◽  
Exogenous Shock ◽  
Unemployment Rates ◽  
World Crisis ◽  
Automatic Stabilizer ◽  
Medium Level ◽  
Using Data ◽  
The Stability

This paper explores the role of employment protection when powerful external crises reduce demand for products. We first present a theoretical framework that shows that employment protection has a U-shaped effect on abnormal unemployment during a negative exogenous shock to an economy. Using data from the 33 OECD countries, we analyze how the level of employment protection affected the stability of unemployment rates during the recent global economic crisis. The results suggest that countries with an intermediate level of employment protection will have more stable unemployment rates during a world crisis. The policy implication of our paper is that countries should seek a medium level of employment protection that may act as an automatic stabilizer of the economy on the macro level.

Stability and mutual impact of perception of parental pressure and infants' social support – A study based on the difference between employment status and household income

2021 ◽  
pp. 002072092199705
Author(s):  
Yong Wang
Keyword(s):  
Household Income ◽  
Employment Status ◽  
Working Mothers ◽  
Social Research ◽  
Research Report ◽  
Parental Pressure ◽  
Income Levels ◽  
Significant Difference ◽  
The Difference ◽  
The Stability

The purpose of this study is to explore the stability and interaction between parental pressure and social research report, as well as the role of employment status and family income levels in this process. This study used a special study on Korean children (PSKC) 2–4 waves. Use t-test, correlation and autoregressive cross-delay modeling to analyze the data. The main findings of this study are: First, over time, parental pressure and mother’s social research report are consistent. Secondly, the pressure of motherhood and childcare has an obvious lagging effect on upbringing, and vice versa. Third, there is no significant difference between working mothers and non-working mothers in terms of the stability of working parents' pressure, social research report and social research report for children's pressure channels. However, parental pressure can only predict the social research report of working mothers. Fourth, there is no significant difference between the stability and interaction of these two structures in household income levels. In short, the results show that, over time, parental pressure is consistent with mother’s social research report. The results also show that there is a significant cross-lag effect between the mothers’ perceptions of mutual pressure analysis. In the process from parental pressure to social research report, I found the difference between working and non-working mothers. The advantage of this study is that the expected longitudinal design was adopted during infancy and the priority between the two structures can be considered. The results of this study can be used as a source of intervention plans to help parents withstand severe parenting pressure and lack of social research report.

scholarly journals Assessment of the Health Behaviours and Value-Based Health Analysis of People Aged 50+ Who Were Hospitalized Due to Cardiovascular Disease

2021 ◽  
Vol 18 (8) ◽  
pp. 4221
Author(s):  
Izabela Gąska ◽  
Katarzyna Sygit ◽  
Elżbieta Cipora ◽  
Marian Sygit ◽  
Anna Pacian ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Statistical Analysis ◽  
Eating Habits ◽  
Health Behaviours ◽  
Public Health Care ◽  
Health Practices ◽  
Body Parts ◽  
Significant Difference ◽  
Health Care Unit ◽  
Student’S T

Introduction: The basic determinant of healthy behaviour—among other human behaviours—is the fact that it consistently affects health. Nowadays, health behaviour studies are considered to be an important method of measuring the health of a population. Objective: To assess the health behaviours and value-based health analysis of people aged 50+ who were hospitalized due to cardiovascular disease, depending on the selected descriptive variables. Materials and methods: The study was conducted between April 2018 and December 2018 among 411 subjects aged 50+ who were hospitalized due to cardiovascular disease at the Independent Public Health Care Unit in Sanok (Podkarpackie voivodship in Poland). The method used in the study was a diagnostic survey. The study used the authors’ survey questionnaire and two standardized tests: Inventory of Health-Related Behaviour (IHB) and List of Health Criteria (LHC). A statistical analysis was carried out in the R program, version 3.5.1. The obtained results were subjected to thorough statistical analysis using the following tests: Student’s t, Mann–Whitney U, ANOVA, Kruskal–Wallis, Fisher’s Least Significant Difference (LSD), Pearson, and Spearman. Results: The strongest correlation between health status and health behaviours (according to the IHB questionnaire) was in the area of ‘health practices’, while the lowest correlation was found in the areas of ‘correct eating habits’ and ‘preventive behaviours’. Based on the LHC questionnaire, the most important health criteria according to the subjects were ‘not feeling any physical ailments’; ‘having all body parts functional’; ‘feeling well’; ‘eating properly’; and ‘infrequent need of going to the doctor’. A positive correlation was found in the group of respondents where the ‘preventive health behaviours’ were more intense; herein, the more important criterion for the respondents was ‘eating properly’. Conclusions: Respondents aged 50+ and hospitalized for cardiovascular diseases indicated (based on the IHB questionnaire) that health behaviours in the area of ‘health practices’ had the strongest correlation with their health, while the lowest correlation was found in the areas of ‘correct eating habits’ and ‘preventive behaviours’. According to the respondents, the most important criteria determining health (according to the LHC questionnaire) included ’not feeling any physical ailments’; ‘having all body parts functional’; ‘feeling well’; ‘eating properly’; and ‘infrequent need of going to the doctor’. Based on the information collected from the respondents, it was found that the most important criteria determining health depended on selected descriptive variables, such as age, gender, place of residence, education, and marital status.

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