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Resting-State Functional Connectivity and Network Analysis of Cerebellum with Respect to IQ and Gender
During the last years, it has been established that the prefrontal and posterior parietal brain lobes, which are mostly related to intelligence, have many connections to cerebellum. However, there is a limited research investigating cerebellum's relationship with cognitive processes. In this st...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Frontiers Media S.A.
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5405083/ https://www.ncbi.nlm.nih.gov/pubmed/28491028 http://dx.doi.org/10.3389/fnhum.2017.00189 |
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author | Pezoulas, Vasileios C. Zervakis, Michalis Michelogiannis, Sifis Klados, Manousos A. |
author_facet | Pezoulas, Vasileios C. Zervakis, Michalis Michelogiannis, Sifis Klados, Manousos A. |
author_sort | Pezoulas, Vasileios C. |
collection | PubMed |
description | During the last years, it has been established that the prefrontal and posterior parietal brain lobes, which are mostly related to intelligence, have many connections to cerebellum. However, there is a limited research investigating cerebellum's relationship with cognitive processes. In this study, the network of cerebellum was analyzed in order to investigate its overall organization in individuals with low and high fluid Intelligence Quotient (IQ). Functional magnetic resonance imaging (fMRI) data were selected from 136 subjects in resting-state from the Human Connectome Project (HCP) database and were further separated into two IQ groups composed of 69 low-IQ and 67 high-IQ subjects. Cerebellum was parcellated into 28 lobules/ROIs (per subject) using a standard cerebellum anatomical atlas. Thereafter, correlation matrices were constructed by computing Pearson's correlation coefficients between the average BOLD time-series for each pair of ROIs inside the cerebellum. By computing conventional graph metrics, small-world network properties were verified using the weighted clustering coefficient and the characteristic path length for estimating the trade-off between segregation and integration. In addition, a connectivity metric was computed for extracting the average cost per network. The concept of the Minimum Spanning Tree (MST) was adopted and implemented in order to avoid methodological biases in graph comparisons and retain only the strongest connections per network. Subsequently, six global and three local metrics were calculated in order to retrieve useful features concerning the characteristics of each MST. Moreover, the local metrics of degree and betweenness centrality were used to detect hubs, i.e., nodes with high importance. The computed set of metrics gave rise to extensive statistical analysis in order to examine differences between low and high-IQ groups, as well as between all possible gender-based group combinations. Our results reveal that both male and female networks have small-world properties with differences in females (especially in higher IQ females) indicative of higher neural efficiency in cerebellum. There is a trend toward the same direction in men, but without significant differences. Finally, three lobules showed maximum correlation with the median response time in low-IQ individuals, implying that there is an increased effort dedicated locally by this population in cognitive tasks. |
format | Online Article Text |
id | pubmed-5405083 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-54050832017-05-10 Resting-State Functional Connectivity and Network Analysis of Cerebellum with Respect to IQ and Gender Pezoulas, Vasileios C. Zervakis, Michalis Michelogiannis, Sifis Klados, Manousos A. Front Hum Neurosci Neuroscience During the last years, it has been established that the prefrontal and posterior parietal brain lobes, which are mostly related to intelligence, have many connections to cerebellum. However, there is a limited research investigating cerebellum's relationship with cognitive processes. In this study, the network of cerebellum was analyzed in order to investigate its overall organization in individuals with low and high fluid Intelligence Quotient (IQ). Functional magnetic resonance imaging (fMRI) data were selected from 136 subjects in resting-state from the Human Connectome Project (HCP) database and were further separated into two IQ groups composed of 69 low-IQ and 67 high-IQ subjects. Cerebellum was parcellated into 28 lobules/ROIs (per subject) using a standard cerebellum anatomical atlas. Thereafter, correlation matrices were constructed by computing Pearson's correlation coefficients between the average BOLD time-series for each pair of ROIs inside the cerebellum. By computing conventional graph metrics, small-world network properties were verified using the weighted clustering coefficient and the characteristic path length for estimating the trade-off between segregation and integration. In addition, a connectivity metric was computed for extracting the average cost per network. The concept of the Minimum Spanning Tree (MST) was adopted and implemented in order to avoid methodological biases in graph comparisons and retain only the strongest connections per network. Subsequently, six global and three local metrics were calculated in order to retrieve useful features concerning the characteristics of each MST. Moreover, the local metrics of degree and betweenness centrality were used to detect hubs, i.e., nodes with high importance. The computed set of metrics gave rise to extensive statistical analysis in order to examine differences between low and high-IQ groups, as well as between all possible gender-based group combinations. Our results reveal that both male and female networks have small-world properties with differences in females (especially in higher IQ females) indicative of higher neural efficiency in cerebellum. There is a trend toward the same direction in men, but without significant differences. Finally, three lobules showed maximum correlation with the median response time in low-IQ individuals, implying that there is an increased effort dedicated locally by this population in cognitive tasks. Frontiers Media S.A. 2017-04-26 /pmc/articles/PMC5405083/ /pubmed/28491028 http://dx.doi.org/10.3389/fnhum.2017.00189 Text en Copyright © 2017 Pezoulas, Zervakis, Michelogiannis and Klados. http://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) or licensor 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 Pezoulas, Vasileios C. Zervakis, Michalis Michelogiannis, Sifis Klados, Manousos A. Resting-State Functional Connectivity and Network Analysis of Cerebellum with Respect to IQ and Gender |
title | Resting-State Functional Connectivity and Network Analysis of Cerebellum with Respect to IQ and Gender |
title_full | Resting-State Functional Connectivity and Network Analysis of Cerebellum with Respect to IQ and Gender |
title_fullStr | Resting-State Functional Connectivity and Network Analysis of Cerebellum with Respect to IQ and Gender |
title_full_unstemmed | Resting-State Functional Connectivity and Network Analysis of Cerebellum with Respect to IQ and Gender |
title_short | Resting-State Functional Connectivity and Network Analysis of Cerebellum with Respect to IQ and Gender |
title_sort | resting-state functional connectivity and network analysis of cerebellum with respect to iq and gender |
topic | Neuroscience |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5405083/ https://www.ncbi.nlm.nih.gov/pubmed/28491028 http://dx.doi.org/10.3389/fnhum.2017.00189 |
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