Changes in neural patterns in persons with aphasia following theory-based generative naming treatment
Sandberg, Chaleece Wyatt
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Aphasia is a language disorder that affects approximately 1 million Americans. Word-finding deficits are characteristic of aphasia and are often targeted in therapy. Generalization from trained to untrained items in word-finding therapy is becoming increasingly important in the development of more cost- and time-effective rehabilitation techniques. However, much remains unknown regarding the neural mechanisms underlying generalization. Thus, this dissertation systematically examined the neural mechanisms underlying successful word-finding treatment, paying particular attention to generalization. Experiment 1 explored the neural correlates of abstract and concrete word processing in three persons with aphasia and three age-matched controls. Experiment 2 examined behavioral outcomes of a theoretically based word generation treatment in 12 persons with aphasia in terms of direct training and generalization effects when abstract words in a particular context-category are trained. Experiment 3 examined neuroplastic changes in activation and functional connectivity associated with behavioral direct training and generalization effects of treatment in 10 persons with aphasia when abstract words are trained. Consistent with current theories of abstract and concrete word processmg, Experiment 1 showed that abstract and concrete words elicited different activation patterns m persons with aphasia, similar to neurologically healthy adults. Experiment 2 showed that training abstract words in a generative naming treatment is not only efficacious, but also efficient because it promotes generalization to concrete words in the same context-category for a majority of participants. Finally, Experiment 3 showed that direct training effects coincided with increased activation and functional connectivity for regions involved in abstract word processing and generalization effects coincided with increased activation and functional connectivity for regions involved in concrete word processing. Inferior frontal gyrus and middle temporal gyrus appear to be important for both direct training and generalization effects of treatment. These results suggest that this treatment is promoting reorganization of function to regions that normally process abstract and concrete words and that direct training and generalization may be subserved by similar neural mechanisms, supporting the notion that the generalization seen behaviorally is a true effect of treatment. The results help inform our understanding of the connection between neuroplasticity and behavioral improvement in treatment in aphasia.
Thesis (Ph.D.)--Boston University N.B.: page 167 appears to be missing from this dissertation. It is unclear whether this is a page numbering error on the author's part, or content is actually missing.