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Building an analysis pipeline to explore at ultra-high field (7T) MRI the laminar distribution of myelin in the human cortex in vivo
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The ventral occipital-temporal cortex (VOTC) is a high-level area in the visual cortex where specific regions are exclusively category-selective for certain visual stimuli. Some studies have demonstrated that absence of visual experience can reshape this functional architecture. In particular, they
demonstrated that crossmodal plasticity due to blindness causes a remodeling of the category topographic map in response to auditory stimuli, reflecting closely the visual category topographic map in
the sighted population. To our knowledge, it has not yet been investigated if this topographic map remodeling in the absence of bottom-up visual inputs during development is also reflected in the myelin
distribution laminar profile within VOTC regions. Nowadays, advancements in neuroimaging techniques allow the mesoscale (submillimeter) in vivo myelin profiling using quantitative markers and 7T
ultra-high field (UHF) magnetic resonance imaging (MRI). The aim of this dissertation is to select the
MRI sequence available in the 7T MRI at the Cyclotron Research Center (ULiège) that would best allow
the quantification of myelin density in the VOTC of sighted and blind individuals and to develop an
open-source pipeline to characterize the myelin laminar distribution in the regions of interest in both
groups. The assessment of noise and variability between scans demonstrated that compared to the multiparametric mapping sequences, MP2RAGE provides quantitative and reproducible high-resolution
myelin maps. The myelin laminar profiles obtained in the regions of interest are in line with previous
ex vivo and in vivo studies, demonstrating that MP2RAGE is a measure allowing myelin cortical profiling in VOTC with faster data acquisition. The pipeline here developed corresponds to the first stages
of the above-mentioned project and will allow in the future comparative studies of the cortical laminar
organization between the blind and sighted populations, improving our understanding about the role of
crossmodal plasticity in reshaping cortex microstructure.
Descrição
Tese de mestrado integrado, Engenharia Biomédica e Biofísica, 2022, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
pipeline plasticidade da mielina camadas corticais in vivo ressonância magnética de campo ultra-alto Teses de mestrado - 2023