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. 2020 Jul 28;22(8):826.
doi: 10.3390/e22080826.

Alteration of the Intra- and Inter-Lobe Connectivity of the Brain Structural Network in Normal Aging

Chi-Wen Jao  1   2 , Jiann-Horng Yeh  3   4 , Yu-Te Wu  1   5 , Li-Ming Lien  3   6 , Yuh-Feng Tsai  4   7 , Kuang-En Chu  8   9 , Chen-Yu Hsiao  7 , Po-Shan Wang  1   10 , Chi Ieong Lau  1   4   11   12   13
Affiliations

Alteration of the Intra- and Inter-Lobe Connectivity of the Brain Structural Network in Normal Aging

Chi-Wen Jao et al. Entropy (Basel). .

Abstract

The morphological changes in cortical parcellated regions during aging and whether these atrophies may cause brain structural network intra- and inter-lobe connectivity alterations are subjects that have been minimally explored. In this study, a novel fractal dimension-based structural network was proposed to measure atrophy of 68 parcellated cortical regions. Alterations of structural network parameters, including intra- and inter-lobe connectivity, were detected in a middle-aged group (30-45 years old) and an elderly group (50-65 years old). The elderly group exhibited significant lateralized atrophy in the left hemisphere, and most of these fractal dimension atrophied regions were included in the regions of the "last-in, first-out" model. Globally, the elderly group had lower modularity values, smaller component size modules, and fewer bilateral association fibers. They had lower intra-lobe connectivity in the frontal and parietal lobes, but higher intra-lobe connectivity in the temporal and occipital lobes. Both groups exhibited similar inter-lobe connecting pattern. The elderly group revealed separations, sparser long association fibers, commissural fibers, and lateral inter-lobe connectivity lost effect, mainly in the right hemisphere. New wiring and reconfiguring modules may have occurred within the brain structural network to compensate for connectivity, decreasing and preventing functional loss in cerebral intra- and inter-lobe connectivity.

Keywords: aging; brain structural network; inter-lobe connectivity; intra-lobe connectivity.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Locations of regions of interest of significantly different fractal dimension values between the middle-aged and elderly groups. The blue dots represent the significantly atrophied regions of interest (ROIs) in the elderly group, while the red dots represent the significantly increased ROIs in the elderly group.
Figure 2
Figure 2
Correlation map of the rearranged Desikan–Killiany atlas between different lobes in the middle-aged group and the elderly group: (a) middle-aged group; (b) elderly group.
Figure 3
Figure 3
Middle-aged group modules. Module 1, 22 nodes in red; module 2, 14 nodes in yellow; module 3, 13 nodes in green; module 4, 11 nodes in turquoise; module 5, 8 nodes in blue.
Figure 4
Figure 4
Elderly group modules. Module 1, 19 nodes in red; module 2, 17 nodes in yellow; module 3, 17 nodes in green; module 4, 8 nodes in turquoise; module 5, 7 nodes in blue.
Figure 5
Figure 5
Intra-modular connectivity of each lobe in the middle-aged group. (a–d) Middle-aged group: (a) frontal lobe; (b) temporal lobe; (c) parietal lobe; (d) occipital lobe. (e–h) Elderly group: (e) frontal lobe; (f) temporal lobe; (g) parietal lobe; (h) occipital lobe.
Figure 6
Figure 6
Inter-modular connectivity between lobes of the middle-age group and the elderly group: (a,c) the long association fiber of each lobe; (b,d) the commissural fibers (transverse fibers) crossing bilateral hemispheres.
Figure 6
Figure 6
Inter-modular connectivity between lobes of the middle-age group and the elderly group: (a,c) the long association fiber of each lobe; (b,d) the commissural fibers (transverse fibers) crossing bilateral hemispheres.
See this image and copyright information in PMC

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