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Neural and Behavioral Dissociations in Aphasic Verb Retrieval

Dresang, Haley C. (2020) Neural and Behavioral Dissociations in Aphasic Verb Retrieval. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Verb-retrieval deficits are pervasive impairments that negatively impact communicative function for individuals living with aphasia, a language disorder caused by brain damage. Behavioral treatments can ameliorate these deficits, but the nature of the deficits remains controversial, and the neurocognitive mechanisms supporting treatment are poorly understood. Aphasia accounts traditionally follow cognitive-linguistic theories, which maintain language as a separate system from other cognitive processes and that aphasia results from distinct damage to language. However, recent cognitive neuroscience theories make contrasting predictions. Grounded cognition claims that language is accomplished by a general-purpose cognitive system that operates over distributed representations encoding both linguistic and non-linguistic knowledge. Rational adaptation predicts that people with aphasia adapt to their language impairments by relying more heavily on non-linguistic knowledge in order to communicate. This dissertation examines these predictions in patients with chronic aphasia due to left-hemisphere stroke and age-matched neurotypical controls. The first experiment examined the degree to which conceptual versus lexical action-processing abilities are impaired and may contribute to verb-retrieval deficits in adults with aphasia. The second experiment employed diffusion spectrum imaging and connectometry analyses to identify white-matter tracts associated with verb retrieval and to assess the involvement of conceptual-motor pathways not considered part of standard dual-stream neurocognitive models of language. The third experiment investigated the extent to which adults with aphasia rationally adapt to their language impairments by relying more on conceptual rather than lexical information during verb retrieval, as compared to controls. The results from these experiments indicate that conceptual processing can be impaired and contributes to verb-retrieval deficits in aphasia. However, relatively unimpaired conceptual processing can ameliorate the influence of lexical impairments on verb-retrieval deficits. Furthermore, the structural integrity of classical motor pathways strongly predicts verb retrieval ability. These findings are consistent with rational adaptation and grounded cognition accounts. This research is the first to systematically evaluate grounded cognition accounts of aphasic language impairments, white-matter connectivity contributions to verb retrieval in aphasia, and rational adaptation to rely on conceptual information. This work provides treatment-relevant evidence by assessing the underlying neurocognitive nature of aphasic impairments and cues that are facilitative of verb retrieval.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Dresang, Haley C.HaleyDresang@pitt.eduhcd80000-0002-8085-2662
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairDickey, Michael
Committee MemberHula, William
Committee MemberFiez,
Committee MemberWarren,
Committee MemberYeh,
Date: 8 September 2020
Date Type: Publication
Defense Date: 20 April 2020
Approval Date: 8 September 2020
Submission Date: 22 July 2020
Access Restriction: 1 year -- Restrict access to University of Pittsburgh for a period of 1 year.
Number of Pages: 214
Institution: University of Pittsburgh
Schools and Programs: School of Health and Rehabilitation Sciences > Communication Science and Disorders
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: aphasia stroke language disorder neuroimaging white matter tracts verb retrieval grounded cognition conceptual processing lexical processing
Date Deposited: 08 Sep 2020 14:26
Last Modified: 08 Sep 2021 05:15


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