Brain changes within the visuo-spatial attentional network in posterior cortical atrophy

Area of Science:

• Neuroimaging
• Neurology
• Neurodegeneration

Background:

• Posterior cortical atrophy (PCA) is a neurodegenerative syndrome primarily affecting visual and visuospatial processing.
• Understanding the full extent of brain network involvement in PCA is crucial for explaining its diverse clinical manifestations.

Purpose of the Study:

• To investigate long-distance deafferentation processes within the frontal-parietal-occipital network in Posterior Cortical Atrophy (PCA) patients.
• To correlate metabolic changes with microstructural integrity in white matter tracts.

Main Methods:

• Utilized a combined Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) approach in ten PCA patients.
• Objective voxel-based [18F]FDG-PET imaging assessed metabolic changes.
• Diffusion Tensor Imaging (DTI) metrics and voxel-based morphometry analyzed white matter integrity and grey matter density in a subgroup.

Main Results:

• Confirmed predominant occipital-temporal and occipital-parietal degeneration in PCA.
• [18F]FDG-PET revealed bilateral hypometabolism in posterior cortical regions and frontal eye fields.
• Fractional anisotropy in the superior longitudinal fasciculus correlated with metabolic changes in the inferior parietal and frontal eye field regions, indicating widespread deafferentation.

Conclusions:

• Combined [18F]FDG-PET and DTI-MRI reveal neurodegeneration extending beyond classical posterior cortical areas in PCA.
• Deafferentation processes within the occipital-parietal-frontal network likely underlie visuospatial and attentional deficits in PCA.
• This study highlights the importance of a network-based approach to understanding PCA pathology.