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Semantic Complexity In Treatment Of Naming Deficits In Aphasia: Evidence From Well-Defined Categories
Full text linkPurpose: Our previous work on manipulating typicality of category exemplars during treatment of naming deficits has shown that training atypical examples generalizes to untrained typical examples but not vice versa. In contrast to natural categories that consist of fuzzy boundaries, well-defined categories (e.g., shapes) have rigid category boundaries. Whether these categories illustrate typicality effects similar to natural categories is under debate. The present study addressed this question in the context of treatment for naming deficits in aphasia. Methods: Using a single-subject experiment design, 3 participants with aphasia received a, semantic feature treatment to improve naming of either typical or atypical items of shapes, while generalization was tested to untrained items of the category. Results: For 2 of the 3 participants, training naming of atypical examples of shapes resulted in improved naming of untrained typical examples. Training typical examples in 1 participant did not improve naming of atypical examples. All 3 participants, however, showed weak acquisition trends. Conclusions: Results of the present study show equivocal support for manipulating typicality as a treatment variable within well-defined categories. Instead, these results indicate that acquisition and generalization effects within well-defined categories such as shapes are overshadowed by their inherent abstractness.Communication Sciences and Disorder
The influence of pre-stroke proficiency on post-stroke lexical semantic performance in bilingual aphasia
Full text linkThe objectives of this study were to examine if pre-stroke proficiency predicts post-stroke lexical semantic performance in Spanish-English bilingual persons with aphasia (PWA) and identify patterns of impairment in this population. A language use questionnaire was administered to 27 Spanish-English bilingual PWA to measure pre-stroke proficiency in both languages. Standardized language assessments in Spanish and English were administered to measure post-stroke lexical semantic performance in both languages. A principal component analysis was conducted on the language use questionnaire measures, revealing Daily Usage, Education, Exposure, and Language Ability Rating as factors that contribute to a person’s proficiency in their first language (L1), and Age of Acquisition, Daily Usage, Family Proficiency, Education, Exposure, Confidence and Language Ability Rating as factors that contribute to a person’s proficiency in their second language (L2). Regression analyses revealed that pre-stroke proficiency significantly predicted post-stroke lexical semantic performance, most strongly in English than in Spanish. Two distinct patterns of impairment emerged within the participants: parallel impairment and differential impairment. Overall, these results confirm that pre-stroke language proficiency is a key determiner of performance on standardized language assessments post-stroke, such that the higher proficiency pre-stroke, the higher performance on standardized tests post stroke. This pattern was more clear when English was L1 or L2 relative to when Spanish was L1 or L2. These results have important implications for assessment and diagnosis of aphasia in bilingual individuals particularly when clinicians need to select the language of assessment
Investigating the relationship between white matter integrity and linguistic and non-linguistic cognition in individuals with chronic aphasia
Full text linkOver time, the idea that specific brain regions underlie language processing has evolved to suggest additional importance of the white matter tracts that connect those regions; however, limited research has been done investigating the functional specialization of white matter tracts in the brain. The goal of this study was to investigate the relationship between white matter tract integrity, as measured by fractional anisotropy, and linguistic and non-linguistic cognition as measured by various behavioral assessments. 28 individuals with aphasia were included in the study, each of whom completed DTI scanning and a battery of linguistic and non-linguistic tasks. Regarding linguistic cognition, results suggested the importance of integrity in the left AF, IFOF, ILF, SLF, and UF across language production and comprehension tasks, with particular implications for left AF, IFOF, and ILF for semantics, and the left AF and SLF, and bilateral IFOF for naming. Interestingly, the right AF showed a negative correlation with naming, suggesting adverse effects of compensatory recruitment of this tract. When looking at non-linguistic cognition, we found significance of left AF and right IFOF, ILF, and SLF integrity for behavioral performance, such that greater integrity in these tracts was associated with greater behavioral performance on non-linguistic tasks. In conclusion, these findings support the importance of left hemisphere dorsal and ventral tracts on linguistic cognition, and reliance on bilateral tracts for non-linguistic cognition
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A single-subject design on the effects of an augmentative and alternative communication (AAC) voice output device on functional communication abilities of an adult with an acquired language disorder
No full textThis study examined the use of a voice output communication aid (VOCA) for a 29-year-old female with severe expressive deficits as a result of an acquired language disorder. The device was used in a clinical and community setting to train production of single words and phrases for requesting and commenting. Baseline measures were obtained prior to treatment and probes were administered weekly to determine learning of the trained items and generalization of the untrained items. Results did not indicate significant learning or generalization of targets. Severe deficits in memory, attention, visuospatial skills, and executive functions were postulated as possible hindrances to learning and generalization. Limited comprehension of the more abstract linguistic features and social aspects of discourse also may have impeded significant improvement post treatmentCommunication Sciences and Disorder
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Effect of typicality on lexical processing of feature-based and perceptually-based categories : a paradigm for isolating semantic feature processing
No full textIn this study, the effect of typicality on lexical access and semantic feature processing was examined by comparing performance on naming and category verification tasks between feature-based (bird, vegetable) and perceptually-based (color) categories. Results demonstrated faster processing of typical exemplars than atypical exemplars across tasks and category types. Naming latencies were similar between feature-based and perceptually-based categories, however verification times were faster for colors than for bird and vegetable stimuli. This is consistent with the theory that color judgments are made through a separate cognitive route that bypasses the semantic system. Results are discussed in relation to models of typicality and lexical processingCommunication Sciences and Disorder
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Verb production in fluent aphasia : a study of lexical organization
No full textThis study examined the nature of verb deficits in 5 individuals with fluent aphasia. Factors related to verb production in fluent aphasia were examined by comparing performance on naming, comprehension, sentence completion, and narrative tasks. Results demonstrated that fluent aphasic individuals showed impaired verb production that was influenced by the syntactic structure of the verbs as well as by semantic features. Fluent participants showed a pattern of progressively greater difficulty with verbs associated with more arguments. The semantic complexity of verbs affected the participants in the sentence completion tasks and narrative tasks.Communication Sciences and Disorder
Neuroplasticity mechanisms in post-stroke aphasia: investigating the differential role of the domain-general multiple demand and language networks
Full text linkLanguage recovery trajectories of people with post-stroke aphasia (PWA) vary widely and while some people reach complete recovery, others have to live with this chronic disability for years. Multiple neuroplasticity mechanisms have been proposed to explain inter-individual differences in language recovery after stroke. Previous literature suggests that spared parts of the language network reorganize over time and regain their language processing function. Furthermore, evidence from other studies indicates that domain-general cognitive control networks, particularly the multiple demand network (MD), could assist the language network in processing language post-stroke. This dissertation first introduces a new theoretical framework to investigate the different neuroplasticity mechanisms supporting language recovery after a stroke accounting for homeostatic plasticity, Hebbian learning plasticity and cognitive control mechanisms. Second, this dissertation examines 1) how the MD network is engaged during language processing in PWA using fMRI precision mapping and 2) how the engagement of the MD network during language processing relates to post-stroke language abilities and stroke damage.
The first study used subject-specific precision mapping to identify the language-specific and MD networks within each PWA and examined differences with age-matched controls in activity and connectivity patterns within and between these two networks during language processing. People with aphasia recruited mainly the spared parts of the language network during language comprehension tasks. Despite a widespread disruption of within-network and between-network connectivity, the language-specific and the MD networks remained functionally dissociated in PWA and the engagement of the MD network in PWA was minimal during language comprehension, similar to controls.
The second study investigated how activity and connectivity within and between the language and MD networks relate to linguistic and nonlinguistic cognitive abilities after a stroke causing aphasia. The findings indicated that the extent of recovered general linguistic abilities was mainly explained by the level of language activity in the language network, whereas verbal expression abilities were better explained by the degree of connectivity between the language and the MD networks. The study further revealed that nonlinguistic cognitive abilities in PWA were related to the strength of the MD network connectivity.
In the third study, we examined the influence of the extent and location of stroke damage in language regions on the compensatory potential of the MD network during language processing. Results suggest that the engagement of the MD network during language processing and its integration with the language network may be beneficial for individuals with extensive damage in the language regions, in particular in temporal regions, and detrimental for individuals with minimal damage in language regions.
The results of these studies suggest that the MD network maintains its domain-general support role in PWA, as it does in controls, when general language processing becomes difficult and neural language resources are reduced. Future studies should further investigate the engagement and interaction of the language and MD networks during language production and at various stages of recovery
Examining the relationship between theory of mind deficits, aphasia severity, and brain health in individuals with post-stroke aphasia
Full text link2025Theory of Mind (ToM) deficits are well-documented in right-hemisphere stroke but understudied in post-stroke aphasia. This study examined ToM impairments in 44 people with aphasia (PWA) using nonverbal belief reasoning tasks and explored links to aphasia severity and brain health. Participants completed two tasks assessing spontaneous inference of another’s perspective, and self-perspective inhibition through short video clips, requiring them to locate a green object. Linear regression models examined the relationship between ToM performance, aphasia severity, as measured by the Western Aphasia Battery-Revised Aphasia Quotient (WAB-R AQ), and brain health, measured by cerebral small vessel disease (CSVD) markers from MRI scans. Using validated visual rating scales, established CSVD markers were evaluated, including white matter hyperintensities, cerebral microbleeds, enlarged perivascular spaces in the basal ganglia and centrum semiovale, and lacunes. Results indicated that ToM deficits were found in 22–36% of participants and these deficits were unrelated to aphasia severity. However, increased enlarged perivascular spaces in the basal ganglia (EPVS-BG) correlated with poorer ToM performance. These findings suggest ToM deficits in PWA may result from broader cerebrovascular pathology rather than language impairment alone. Recognizing these deficits early could improve rehabilitation outcomes and aid clinicians in identifying at-risk individuals, emphasizing the need for a multifactorial approach to aphasia treatment
A novel eye tracking paradigm for detecting semantic and phonological activation in aphasia
Full text linkMany persons with aphasia (PWA), who have trouble communicating after a stroke, have difficulty naming objects, frequently producing speech errors. Picture (confrontation) naming tasks are commonly used to assess the presence and/or severity of naming difficulties, but these tests do not adequately capture the underlying cause of impairment. This project addresses the limitations of the standard picture naming paradigm by incorporating the measurement of eye movements, thereby providing a precise estimate of participants’ visual attention during the task. While prior studies have measured eye movements to distractor pictures when a spoken word is presented, to our knowledge no eye tracking studies have examined picture naming with written distractors in aphasia. Using a novel approach, we measured PWA’s and healthy controls’ eye movements as they selected the correct written word corresponding to the picture over other related words (semantically and sound-based distractors). The results of this project seek to: (1) indicate the feasibility of a novel eye tracking paradigm to study both intact and impaired lexical retrieval; (2) provide detailed information about the nature and time course of impaired naming; and (3) yield insight into the relative preservation of semantic and phonological representations in aphasia
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