Prenatal cerebral ischemia disrupts MRI-defined cortical microstructure through disturbances in neuronal arborization

Area of Science:

• Neuroscience
• Developmental Biology
• Medical Imaging

Background:

• Preterm birth survivors often experience cognitive and learning disabilities linked to abnormal cerebral cortical growth.
• The underlying mechanisms for these neurodevelopmental deficits remain poorly understood.

Purpose of the Study:

• To investigate the relationship between cerebral ischemia, cortical growth disturbances, and neuronal morphology in a preterm large-animal model.
• To explore the potential of diffusion magnetic resonance imaging (dMRI) fractional anisotropy (FA) as a biomarker for impaired cortical development.

Main Methods:

• Utilized ex vivo diffusion magnetic resonance imaging (dMRI) in a preterm large-animal model.
• Analyzed pyramidal neuron morphology, including dendritic arbor expansion and synaptic density.
• Measured dendritic branch orientation distribution and correlated it with cortical FA measurements.

Main Results:

• Cerebral ischemia in preterm models impaired cortical growth and the normal decrease in cortical fractional anisotropy (FA).
• Cortical deficits were associated with reduced dendritic arbor expansion and synaptic density in pyramidal neurons.
• Dendritic branch orientation corresponded with increased FA in affected areas, suggesting a link between FA and neuronal structure.

Conclusions:

• Impaired cortical growth in preterm birth survivors is linked to widespread disruptions in neuronal dendritic arbor and synapse formation.
• These neuronal disturbances may underlie the cognitive and learning disabilities observed in preterm survivors.
• Cortical FA measurement shows promise as a noninvasive method for detecting neurological disorders affecting brain development.