Network changes associated with right anterior temporal lobe atrophy: insight into unique symptoms

Area of Science:

• Neuroscience
• Cognitive Neurology
• Neuroimaging

Background:

• Semantic behavioural variant frontotemporal dementia (svFTD) is a right-sided syndrome characterized by temporal lobe atrophy and distinct behavioral/semantic changes.
• It shares mechanisms with semantic variant primary progressive aphasia but its network correlates are less understood.
• Understanding right-hemisphere network alterations is crucial for svFTD.

Purpose of the Study:

• Investigate functional connectivity in right-sided speech and language networks in svFTD.
• Examine the relationship between network connectivity and specific clinical symptoms like socioemotional deficits and hyper-focus.
• Test hypotheses linking ventral network connectivity to socioemotional deficits and dorsal network connectivity to behavioral rigidity.

Main Methods:

• Used functional MRI (fMRI) with seed-based intrinsic connectivity analyses.
• Analyzed data from 22 individuals with svFTD and 48 healthy controls.
• Correlated functional connectivity in right ventral and dorsal networks with cognitive/behavioral scores, controlling for atrophy.

Main Results:

• svFTD patients showed reduced functional connectivity in the right ventral semantic network compared to controls.
• This reduced ventral connectivity correlated with socioemotional-semantic deficits.
• Increased functional connectivity was found in the right dorsal network, associated with heightened hyper-focus behaviors.

Conclusions:

• Findings suggest distinct network alterations in svFTD: reduced ventral connectivity impacts socioemotional processing, while increased dorsal connectivity relates to behavioral rigidity.
• Altered functional dynamics in both damaged and spared networks contribute to svFTD's clinical presentation.
• This highlights the complex interplay of neural networks in svFTD.