Depth-dependent intracortical myelin organization in the living human brain determined by in vivo ultra-high field magnetic resonance imaging

Emma Sprooten, Rafael O'Halloran, Juliane Dinse, Won Hee Lee, Dominik Andreas Moser, Gaelle Eve Doucet, Morgan Goodman, Hannah Krinsky, Alejandro Paulino, Alexander Rasgon, Evan Leibu, Priti Balchandani, Matilde Inglese, Sophia Frangou

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Background: Intracortical myelin is a key determinant of neuronal synchrony and plasticity that underpin optimal brain function. Magnetic resonance imaging (MRI) facilitates the examination of intracortical myelin but presents with methodological challenges. Here we describe a whole-brain approach for the in vivo investigation of intracortical myelin in the human brain using ultra-high field MRI. Methods: Twenty-five healthy adults were imaged in a 7 Tesla MRI scanner using diffusion-weighted imaging and a T 1 -weighted sequence optimized for intracortical myelin contrast. Using an automated pipeline, T 1 values were extracted at 20 depth-levels from each of 148 cortical regions. In each cortical region, T 1 values were used to infer myelin concentration and to construct a non-linearity index as a measure the spatial distribution of myelin across the cortical ribbon. The relationship of myelin concentration and the non-linearity index with other neuroanatomical properties were investigated. Five patients with multiple sclerosis were also assessed using the same protocol as positive controls. Results: Intracortical T 1 values decreased between the outer brain surface and the gray-white matter boundary following a slope that showed a slight leveling between 50% and 75% of cortical depth. Higher-order regions in the prefrontal, cingulate and insular cortices, displayed higher non-linearity indices than sensorimotor regions. Across all regions, there was a positive association between T 1 values and non-linearity indices (P < 10 −5 ). Both T 1 values (P < 10 −5 ) and non-linearity indices (P < 10 −15 ) were associated with cortical thickness. Higher myelin concentration but only in the deepest cortical levels was associated with increased subcortical fractional anisotropy (P = 0.05). Conclusions: We demonstrate the usefulness of an automatic, whole-brain method to perform depth-dependent examination of intracortical myelin organization. The extracted metrics, T 1 values and the non-linearity index, have characteristic patterns across cortical regions, and are associated with thickness and underlying white matter microstructure.

Original languageEnglish (US)
Pages (from-to)27-34
Number of pages8
JournalNeuroImage
Volume185
DOIs
StatePublished - Jan 15 2019

Keywords

  • Cortical depth-levels
  • Myeloarchitecture
  • Neuroimaging
  • Ultra-high field

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience

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    Sprooten, E., O'Halloran, R., Dinse, J., Lee, W. H., Moser, D. A., Doucet, G. E., Goodman, M., Krinsky, H., Paulino, A., Rasgon, A., Leibu, E., Balchandani, P., Inglese, M., & Frangou, S. (2019). Depth-dependent intracortical myelin organization in the living human brain determined by in vivo ultra-high field magnetic resonance imaging. NeuroImage, 185, 27-34. https://doi.org/10.1016/j.neuroimage.2018.10.023