Resting state functional brain networks associated with emotion processing in frontotemporal lobar degeneration

Area of Science:

• Neuroscience
• Neurology
• Brain Imaging

Background:

• Frontotemporal lobar degeneration (FTLD) encompasses a group of neurodegenerative diseases affecting behavior, language, and motor function.
• Emotion processing deficits are a common but poorly understood symptom across various FTLD subtypes.
• Resting-state functional connectivity (rs-FC) offers insights into intrinsic brain network organization and its relation to cognitive functions.

Purpose of the Study:

• To investigate the relationship between emotion processing abilities and resting-state functional connectivity (rs-FC) in the brain networks of FTLD patients.
• To compare these relationships between FTLD patients and healthy controls.
• To explore whether rs-FC alterations in emotion processing are consistent across different FTLD subtypes.

Main Methods:

• Eighty FTLD patients (including behavioral variant frontotemporal dementia, primary progressive aphasia, progressive supranuclear palsy syndrome, motor neuron disease) and 65 healthy controls underwent resting-state functional magnetic resonance imaging (rs-fMRI).
• Emotion processing was assessed using the Comprehensive Affect Testing System (CATS).
• Correlations between CATS scores and rs-FC within critical brain networks were analyzed, with mean rs-FC compared across FTLD groups.

Main Results:

• FTLD patients exhibited significantly poorer performance on emotion processing tasks (CATS) compared to controls.
• In controls, rs-FC in cerebellar, visuo-associative, and visuo-spatial networks correlated with specific emotion processing skills.
• In FTLD, associations between rs-FC and emotion processing involved a broader range of brain regions, including orbitofrontal cortex, parietal regions, and basal ganglia, suggesting widespread network alterations.

Conclusions:

• FTLD is associated with significant deficits in emotion processing and altered brain network connectivity.
• The pattern of rs-FC alterations related to emotion processing in FTLD involves more brain regions than in controls, potentially due to loss of functional specificity and compensatory mechanisms.
• The similar rs-FC patterns across all FTLD groups suggest a common underlying mechanism for emotion processing dysfunction, irrespective of the specific clinical presentation or atrophy pattern.