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Gene expression; Histology; Neurodegeneration; Ultra-high field MRI
Abstract:
Ultra-high field MRI across the depth of the cortex has the potential to provide ana-
tomically precise biomarkers and mechanistic insights into neurodegenerative disease
like Huntington's disease that show layer-selective vulnerability. Here we compare
multi-parametric mapping (MPM) measures across cortical depths for a 7T 500 m
whole brain acquisition to (a) layer-specific cell measures from the von Economo his-
tology atlas, (b) layer-specific gene expression, using the Allen Human Brain atlas and
(c) white matter connections using high-fidelity diffusion tractography, at a 1.3 mm
isotropic voxel resolution, from a 300mT/m Connectom MRI system. We show that
R2*, but not R1, across cortical depths is highly correlated with layer-specific cell
number and layer-specific gene expression. R1- and R2*-weighted connectivity
strength of cortico-striatal and intra-hemispheric cortical white matter connections
was highly correlated with grey matter R1 and R2* across cortical depths. Limitations
of the layer-specific relationships demonstrated are at least in part related to the high
cross-correlations of von Economo atlas cell counts and layer-specific gene expres-
sion across cortical layers. These findings demonstrate the potential and limitations
of combining 7T MPMs, gene expression and white matter connections to provide an
anatomically precise framework for tracking neurodegenerative disease.
