Dissertation
Aphasia as a network disorder: investigating deficits and treatment through a network-based framework
Doctor of Philosophy (Ph.D.), Drexel University
Jun 2026
DOI:
https://doi.org/10.17918/00011396
Abstract
Aphasia is one of the most prevalent and debilitating consequences of left hemisphere stroke, causing significant disruptions to communication, quality of life, and independence. While decades of research have established the brain regions and white-matter pathways critical for language processing, our ability to understand and treat aphasia has not kept pace with our theoretical understanding of the disorder. The evidence increasingly supports conceptualizing aphasia as a network disorder. Specifically, aphasia deficits arise not from damage to a single region, but from disruptions across a broader, interconnected system. However, the tools and frameworks used to study and treat aphasia have yet to fully embrace this perspective. This dissertation consists of three studies: 1) to examine how the network roles of left hemisphere language regions and their right hemisphere homotopes shift after stroke and relate to aphasia severity, 2) to directly test the interhemispheric inhibition hypothesis by characterizing directed functional connectivity of the right pars triangularis (rPTr) at the individual level, and 3) to identify the structural network properties of the rPTr that predict TMS-induced naming improvement. The findings indicate that 1) eigenvector centrality shows the most consistent network shifts after stroke, with right hemisphere regions showing increased centrality in persons with aphasia, 2) individual connectivity profiles of the rPTr are highly heterogeneous and do not support the interhemispheric inhibition hypothesis, and 3) structural paths from the rPTr to the right middle temporal gyrus predict naming improvement after TMS. This dissertation concludes by discussing how individual differences in network connectivity lay the foundation for personalized approaches to understanding aphasia severity and TMS efficacy and by considers how network science can advance the ability of the field to characterize and predict recovery at the individual level.
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Details
- Title
- Aphasia as a network disorder
- Creators
- Harrison M. Stoll
- Contributors
- John D. Medaglia (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University
- Number of pages
- viii, 175 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Psychological and Brain Sciences (Psychology); College of Arts and Sciences; Drexel University
- Other Identifier
- 991022185675004721