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A Graphlet-Based Topological Characterization of the Resting-State Network in Healthy People

In this paper, we propose a graphlet-based topological algorithm for the investigation of the brain network at resting state (RS). To this aim, we model the brain as a graph, where (labeled) nodes correspond to specific cerebral areas and links are weighted connections determined by the intensity of...

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Autores principales: Finotelli, Paolo, Piccardi, Carlo, Miglio, Edie, Dulio, Paolo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8113409/
https://www.ncbi.nlm.nih.gov/pubmed/33994939
http://dx.doi.org/10.3389/fnins.2021.665544
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author Finotelli, Paolo
Piccardi, Carlo
Miglio, Edie
Dulio, Paolo
author_facet Finotelli, Paolo
Piccardi, Carlo
Miglio, Edie
Dulio, Paolo
author_sort Finotelli, Paolo
collection PubMed
description In this paper, we propose a graphlet-based topological algorithm for the investigation of the brain network at resting state (RS). To this aim, we model the brain as a graph, where (labeled) nodes correspond to specific cerebral areas and links are weighted connections determined by the intensity of the functional magnetic resonance imaging (fMRI). Then, we select a number of working graphlets, namely, connected and non-isomorphic induced subgraphs. We compute, for each labeled node, its Graphlet Degree Vector (GDV), which allows us to associate a GDV matrix to each one of the 133 subjects of the considered sample, reporting how many times each node of the atlas “touches” the independent orbits defined by the graphlet set. We focus on the 56 independent columns (i.e., non-redundant orbits) of the GDV matrices. By aggregating their count all over the 133 subjects and then by sorting each column independently, we obtain a sorted node table, whose top-level entries highlight the nodes (i.e., brain regions) most frequently touching each of the 56 independent graphlet orbits. Then, by pairwise comparing the columns of the sorted node table in the top-k entries for various values of k, we identify sets of nodes that are consistently involved with high frequency in the 56 independent graphlet orbits all over the 133 subjects. It turns out that these sets consist of labeled nodes directly belonging to the default mode network (DMN) or strongly interacting with it at the RS, indicating that graphlet analysis provides a viable tool for the topological characterization of such brain regions. We finally provide a validation of the graphlet approach by testing its power in catching network differences. To this aim, we encode in a Graphlet Correlation Matrix (GCM) the network information associated with each subject then construct a subject-to-subject Graphlet Correlation Distance (GCD) matrix based on the Euclidean distances between all possible pairs of GCM. The analysis of the clusters induced by the GCD matrix shows a clear separation of the subjects in two groups, whose relationship with the subject characteristics is investigated.
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spelling pubmed-81134092021-05-13 A Graphlet-Based Topological Characterization of the Resting-State Network in Healthy People Finotelli, Paolo Piccardi, Carlo Miglio, Edie Dulio, Paolo Front Neurosci Neuroscience In this paper, we propose a graphlet-based topological algorithm for the investigation of the brain network at resting state (RS). To this aim, we model the brain as a graph, where (labeled) nodes correspond to specific cerebral areas and links are weighted connections determined by the intensity of the functional magnetic resonance imaging (fMRI). Then, we select a number of working graphlets, namely, connected and non-isomorphic induced subgraphs. We compute, for each labeled node, its Graphlet Degree Vector (GDV), which allows us to associate a GDV matrix to each one of the 133 subjects of the considered sample, reporting how many times each node of the atlas “touches” the independent orbits defined by the graphlet set. We focus on the 56 independent columns (i.e., non-redundant orbits) of the GDV matrices. By aggregating their count all over the 133 subjects and then by sorting each column independently, we obtain a sorted node table, whose top-level entries highlight the nodes (i.e., brain regions) most frequently touching each of the 56 independent graphlet orbits. Then, by pairwise comparing the columns of the sorted node table in the top-k entries for various values of k, we identify sets of nodes that are consistently involved with high frequency in the 56 independent graphlet orbits all over the 133 subjects. It turns out that these sets consist of labeled nodes directly belonging to the default mode network (DMN) or strongly interacting with it at the RS, indicating that graphlet analysis provides a viable tool for the topological characterization of such brain regions. We finally provide a validation of the graphlet approach by testing its power in catching network differences. To this aim, we encode in a Graphlet Correlation Matrix (GCM) the network information associated with each subject then construct a subject-to-subject Graphlet Correlation Distance (GCD) matrix based on the Euclidean distances between all possible pairs of GCM. The analysis of the clusters induced by the GCD matrix shows a clear separation of the subjects in two groups, whose relationship with the subject characteristics is investigated. Frontiers Media S.A. 2021-04-28 /pmc/articles/PMC8113409/ /pubmed/33994939 http://dx.doi.org/10.3389/fnins.2021.665544 Text en Copyright © 2021 Finotelli, Piccardi, Miglio and Dulio. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Neuroscience
Finotelli, Paolo
Piccardi, Carlo
Miglio, Edie
Dulio, Paolo
A Graphlet-Based Topological Characterization of the Resting-State Network in Healthy People
title A Graphlet-Based Topological Characterization of the Resting-State Network in Healthy People
title_full A Graphlet-Based Topological Characterization of the Resting-State Network in Healthy People
title_fullStr A Graphlet-Based Topological Characterization of the Resting-State Network in Healthy People
title_full_unstemmed A Graphlet-Based Topological Characterization of the Resting-State Network in Healthy People
title_short A Graphlet-Based Topological Characterization of the Resting-State Network in Healthy People
title_sort graphlet-based topological characterization of the resting-state network in healthy people
topic Neuroscience
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8113409/
https://www.ncbi.nlm.nih.gov/pubmed/33994939
http://dx.doi.org/10.3389/fnins.2021.665544
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