Abnormal network connections to early visual cortex in posterior cortical atrophy

Area of Science:

• Neuroscience
• Neuroimaging
• Alzheimer's Disease Research

Background:

• Posterior Cortical Atrophy (PCA) is a visual variant of Alzheimer's disease.
• PCA involves higher-order visual disorders and parieto/temporo-occipital atrophy.
• Previous research indicates remote functional impairments in brain networks and the calcarine sulcus (V1).

Purpose of the Study:

• To investigate retinotopic patterns of functional connectivity between large-scale brain networks and V1.
• To compare these patterns in PCA patients versus normally sighted individuals.

Main Methods:

• Resting-state fMRI and T1 anatomical scans were acquired from 11 PCA patients and 17 healthy controls.
• Default Mode Network (DMN) and Fronto Parietal Network (FPN) connectivity to V1 were analyzed.
• Differences in connectivity patterns were evaluated at the whole brain and V1 levels.

Main Results:

• While whole-brain network connectivity showed some differences, DMN and FPN connectivity patterns within V1 differed significantly between groups.
• Healthy controls exhibited expected retinotopic V1 connectivity (foveal with FPN, peripheral with DMN).
• PCA patients lacked this clear eccentric V1 connectivity pattern.

Conclusions:

• PCA patients demonstrate a loss of functional specialization along the calcarine sulcus (V1).
• This impairment, potentially affecting large-scale networks, may underlie visual disabilities in PCA.
• Understanding these V1 functional alterations is crucial for explaining PCA-related visual deficits.