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Lesion-induced changes to the network controllability of the right pars triangularis in aphasia
Thesis   Open access

Lesion-induced changes to the network controllability of the right pars triangularis in aphasia

Harrison Stoll
Master of Science (M.S.), Drexel University
Dec 2023
DOI:
https://doi.org/10.17918/00002012
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Abstract

Aphasia Language disorders Neural networks (Neurobiology)
Left hemisphere stroke causes functional changes to the language network and may shift aspects of language processing to right hemisphere homotopes of perislyvian language regions. The result of language processing shifting to the right hemisphere activity is unclear. For example, several studies suggest the right pars triangularis (rPTr) engagement in language processing corresponds to higher dysfunction. As a result, the region is often a site for inhibitory neuromodulation, with evidence that inhibiting the region improves language function in persons with aphasia (PWA). However, studies have also found no relationship between rPTr functional activity and language performance in PWA. The mixed evidence regarding the rPTr suggests additional work is needed to understand the role of the region in language recovery. To clarify the role of this region, we sought to investigate if left hemisphere stroke leads to changes in the structural topological properties of the region. We used measures from network control theory (NCT) to compare the theoretical capacity of the rPTr to integrate communication across brain modules (i.e., boundary controllability, BC) in the brain, in 60 PWA and 62 controls. We also examined if BC corresponded to different aspects of language processing (i.e., semantic and phonological) in PWA. We found that PWA had a higher BC in the rPTr relative to controls. Higher BC was also associated with fewer phonological errors in a picture naming task but not semantic errors. These findings contribute to our broader understanding of structural language network reorganization in the right hemisphere regions and establishes a link with structural changes and language deficits.

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