Van Houten, E. E. W. | Search bioRxiv

bioRxiv2025

Mechanical Properties of the Developing Brain in a Model of Fetal Alcohol Spectrum Disorders and Relationships to Perineuronal Net Integrity

Neuroimaging is a useful tool for examining altered neurodevelopmental trajectories in fetal alcohol spectrum disorders (FASD). FASD affects 1 in 20 infants in the United States with higher prevalence in specific regions across the globe. Advanced neuroimaging methods, such as volumetric morphometry and diffusion-weighted imaging, are critical for determining the effectiveness of interventions that support neurodevelopment in FASD. In this study, we introduce the use of magnetic resonance elastography (MRE), a cutting-edge neuroimaging technique used to measure the mechanical properties of brain tissue, to assess the impact of alcohol exposure and combined exercise and environmental complexity intervention on neurodevelopment in a rat model of FASD. Our results indicate that brain stiffness is reduced in juvenile alcohol-exposed rats which is recovered to baseline by adulthood, and damping ratio increases in all rats with age. Additionally, we quantified cortical perineuronal net (PNN) density which follows similar trends to shear stiffness and damping ratio, suggesting MRE may be an effective method for noninvasively monitoring FASD progression related to extracellular matrix integrity.

neuroscience↗

bioRxiv2024

Mechanical Properties of White Matter Tracts in Aging Assessed via Anisotropic MR Elastography

Magnetic resonance elastography (MRE) is a promising neuroimaging technique to probe tissue microstructure, which has revealed widespread softening with loss of structural integrity in the aging brain. Traditional MRE approaches assume mechanical isotropy. However, white matter is known to be anisotropic from aligned, myelinated axonal bundles, which can lead to uncertainty in mechanical property estimates in these areas when using isotropic MRE. Recent advances in anisotropic MRE now allow for estimation of shear and tensile anisotropy, along with substrate shear modulus, in white matter tracts. The objective of this study was to investigate age-related differences in anisotropic mechanical properties in human brain white matter tracts for the first time. Anisotropic mechanical properties in all tracts were found to be significantly lower in older adults compared to young adults, with average property differences ranging between 0.028-0.107 for shear anisotropy and between 0.139-0.347 for tensile anisotropy. Stiffness perpendicular to the axonal fiber direction was also significantly lower in older age, but only in certain tracts. When compared with fractional anisotropy measures from diffusion tensor imaging, we found that anisotropic MRE measures provided additional, complementary information in describing differences between the white matter integrity of young and older populations. Anisotropic MRE provides a new tool for studying white matter structural integrity in aging and neurodegeneration.

neuroscience↗