Introducing axonal myelination in connectomics: a preliminary analysis of g-ratio distribution in healthy subjects

Mancini, Matteo, Giulietti, Giovanni, Dowell, Nicholas, Spanò, Barbara, Harrison, Neil, Bozzali, Marco and Cercignani, Mara (2017) Introducing axonal myelination in connectomics: a preliminary analysis of g-ratio distribution in healthy subjects. NeuroImage. ISSN 1053-8119

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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 characterise 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.

Item Type: Article
Keywords: g-ratio: connectome; myelin; graph theory; microstructure; structural connectivity; diffusion weighted imaging.
Schools and Departments: Brighton and Sussex Medical School > Neuroscience
Subjects: R Medicine
R Medicine > RC Internal medicine > RC0321 Neurosciences. Biological psychiatry. Neuropsychiatry
Depositing User: Alexei Fisk
Date Deposited: 19 Sep 2017 11:42
Last Modified: 19 Sep 2017 11:42
URI: http://sro.sussex.ac.uk/id/eprint/70231

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