Introducing Axonal Myelination in Connectomics: a Preliminary Analysis of G-ratio Distribution in Healthy Subjects

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Introducing Axonal Myelination in Connectomics: a Preliminary Analysis of G-ratio Distribution in Healthy Subjects

Mancini, M; Giulietti, G; Dowell, N; Spano, B; Harrison, N; Bozzali, M; Cercignani, M; (2018) Introducing Axonal Myelination in Connectomics: a Preliminary Analysis of G-ratio Distribution in Healthy Subjects. NeuroImage , 182 pp. 351-359. 10.1016/j.neuroimage.2017.09.018. Green open access

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Abstract

Microstructural imaging and connectomics are two research areas that hold great potential for investigating brain structure and function. Combining these two approaches can lead to a better and more complete characterization of the brain as a network. The aim of this work is characterizing the connectome from a novel perspective using the myelination measure given by the g-ratio. The g-ratio is the ratio of the inner to the outer diameters of a myelinated axon, whose aggregated value can now be estimated in vivo using MRI. In two different datasets of healthy subjects, we reconstructed the structural connectome and then used the g-ratio estimated from diffusion and magnetization transfer data to characterize the network structure. Significant characteristics of g-ratio weighted graphs emerged. First, the g-ratio distribution across the edges of the graph did not show the power-law distribution observed using the number of streamlines as a weight. Second, connections involving regions related to motor and sensory functions were the highest in myelin content. We also observed significant differences in terms of the hub structure and the rich-club organization suggesting that connections involving hub regions present higher myelination than peripheral connections. Taken together, these findings offer a characterization of g-ratio distribution across the connectome in healthy subjects and lay the foundations for further investigating plasticity and pathology using a similar approach.

Type:	Article
Title:	Introducing Axonal Myelination in Connectomics: a Preliminary Analysis of G-ratio Distribution in Healthy Subjects
Location:	Montreal, CANADA
Open access status:	An open access version is available from UCL Discovery
DOI:	10.1016/j.neuroimage.2017.09.018
Publisher version:	https://doi.org/10.1016/j.neuroimage.2017.09.018
Language:	English
Additional information:	This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords:	g-ratio, connectome, myelin, graph theory, microstructure, structural connectivity, diffusion weighted imaging.
UCL classification:	UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng
URI:	https://discovery.ucl.ac.uk/id/eprint/10060430