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Thesis (M.S.)--East Carolina University, 2009. / Advisor: John Heilmann. Title from PDF t.p. (viewed July 1, 2010). Presented to the faculty of the Department of Communication Sciences and Disorders. Includes bibliographical references.

The current investigation examined perturbation and adaptation during language comprehension in young normal subjects. Using a dynamic system framework, induced instability was studied by increasing perceptual demand (compressed sentences), syntactic demand, or both. Two experiments were conducted, one behavioral and one using fMRI technology, to explore the relations between brain responses and behavior. This study examines if changes in rate of speech, syntax, or both induce an instability, or perturbation, with subsequent adaptation in which subjects regain a previous stable state. Dependent measures in the behavioral study were accuracy and reaction time based indices of perturbation, adaptation, and stability. Results of the behavioral study demonstrated that language comprehension can be perturbed by changes in syntactic complexity or syntactic + perceptual complexity. Further, it was found that subjects adapted to being perturbed. The more complex the stimulus, the longer it took for subjects to adapt. The second experiment used fMRI to measure brain activation associated with perturbation and adaptation of language. Several brain regions showed increases in activation with increasing complexity (i.e., perturbation). Some regions (e.g., the superior parietal lobule) appeared more active when the perturbation was perceptual and others (e.g., the left inferior frontal gyrus) more active when the perturbation was syntactic in nature. These regions either remained active during the adaptation process, or reduced in activation during adaptation suggesting a role specific role in perturbation. These results suggest that subjects develop and maintain a representation of either the syntactic frame (i.e., via priming), a conscious strategy for accommodating syntactic complexity, or rate normalization schema. Thus, the brain regions that remain active during adaptation may be used to maintain the linguistic or perceptual frame. Within a dynamic system framework, the development of these representations, which occurs over a few items, serves as an attractor to which subjects are drawn each time they are perturbed. Like other complex systems, once instability occurs, there needs to be a strong attractor state to pull subjects into stability that permits appropriate performance to continue.

The purpose of this study was to investigate the relationship between aphasia severity and cerebral perfusion and lesion size in stroke. Nine subjects with acute ischemic stroke were examined within 24 hours of symptom onset and six were reexamined at one-month post-stroke. Examination included aphasia testing, testing of face discrimination ability, administration of the National Institutes of Health Stroke Scale, and perfusion MRI (PI), diffusion MRI (DWI), and T2-weighted MRI (T2-MRI). Subjects with a variety of aphasia types and a large range of aphasia severity participated in the study. MR images were visually inspected to verify perfusion and diffusion abnormalities. Perfusion abnormality was quantified by calculating a perfusion signal ratio of the affected hemisphere over the whole image (left/whole = ratio). Lesion volume was calculated from the DWI and T2-MRI. A perfusion abnormality larger than a DWI lesion was observed in 8 of 9 subjects. Minimal lesions were observed on DWI in three of the subjects while their PI revealed significant perfusion abnormality. Correlation coefficients (Spearman) between aphasia severity and hypoperfusion were significant in the acute stage and again at one-month post-stroke. Five of six subjects that were reexamined at one-month post-stroke experienced significant aphasia recovery. Visual inspection of their PI scans suggests that aphasia recovery was accompanied by increase in cerebral perfusion. The correlation between aphasia severity and lesion size was not statistically significant in the acute stage or at one-month post-stroke. Consequently, it is probable that cerebral hypoperfusion is a better predictor of aphasia severity and recovery in early stroke than lesion volume.

This study investigated the fast-mapping ability of young children with normal language (NL) and specific language impairment (SLI). It compared their ability to fast-map semantic and lexical information in different conditions. Children had to fast map visual information only, visual plus non-linguistic auditory information, and visual plus linguistic auditory information. Children with SLI performed worse than children with NL overall. They showed specific deficits when the task did not meet their expectations and when they were asked to map phonologically infrequent linguistic information. A nonword repetition task was correlated with both semantic and lexical fast-mapping. The findings are discussed in light of their support for a limited capacity model of processing, and for the need to evaluate children with SLI for semantic deficits.

Purpose. The purpose of this study was to examine the influence of visual information on the intelligibility of dysarthric speech. The two research questions posed by this study were: (1) Does the presentation mode (auditory-only versus auditory-visual) influence the intelligibility of a homogeneous group of speakers with dysarthria? and (2) Does the experience of the listener (experienced versus inexperienced with dysarthric speech) influence the intelligibility scores of these speakers? Background. Investigations of speakers with hearing impairment and laryngectomy have indicated that intelligibility scores are higher in an auditory-visual mode compared to an auditory-only mode of presentation. Studies of speakers with dysarthria have resulted in mixed findings. Methodological issues such as heterogeneity of speaker groups and factors related to the stimuli may have contributed to these mixed findings. Method. Eight speakers with dysarthria related to Parkinson disease were audio and video tape-recorded reading sentences. Movie files were created in which an auditory-only condition containing the speaker's voice but no visual image of the speaker and an auditory-visual condition containing the speaker's voice and a view of his/her face. Two groups of listeners (experienced and inexperienced with dysarthric speech) completed listening sessions in which they listened to (auditory-only) and watched and listened to (auditory-visual) the movies and transcribed what they heard each speaker say. Results. Although auditory-visual scores were significantly higher than auditory-only intelligibility scores, the difference between these scores was influenced by the order in which the two conditions were presented. A speaker effect was found across presentation modes, with less intelligible speakers demonstrating greater benefit from the inclusion of visual information. No statistically significant difference was found between the two listener groups in this study. Conclusions. These findings suggest that clinicians should include assessment of both auditory-only and auditory-visual intelligibility measures in speakers with Parkinson disease. Management of intelligibility impairment in these individuals should consider whether visual information is beneficial to listeners.

The relationship between brain invaded by tumor and consequent word retrieval deficits was investigated. Performance scores from 10 individuals who underwent craniotomy for tumor resection were obtained using contexts of constrained naming, verbal fluency, and picture description during pre- and post-craniotomy. This study described qualitative and quantitative differences of impairment to elucidate the nature and extent of naming impairment in individuals with cerebral hemisphere tumors. For all tasks, independent of group, performance decrements were reported pre-operatively in relation to normative data, with subsequent post-operative decline. This was particularly true for the Left Hemisphere Group who exhibited poorer performance than the Right Hemisphere Group. It was expected that the Frontal Group would have greater difficulty on tasks requiring intact frontal lobe function (i.e. Verbal Fluency), but the Non-Frontal Group performed more poorly. Surprisingly, the Frontal Lobe Group showed the smallest decrement, and the Non-Frontal and Left Hemisphere Groups showed the worst performance overall. Pre- and post-operatively, all subjects exhibited greater word retrieval deficits than normal controls during verbal fluency tasks. The overall disruption of word retrieval across tasks was predictable for time of examination, but not for site of lesion. The results of this study suggest that the word retrieval deficits of brain tumor patients may differ from traditional aphasia profiles. This knowledge may contribute to a better understanding of language processing and production in tumor-related aphasia.

Aphasia has a significant negative impact on an individual's ability to communicate in his or her daily living environment. When this environment offers limited communication opportunities, as is generally believed to be the case in long-term care facilities such as nursing homes, aphasic individuals may suffer doubly. These individuals have to deal not only with limited communication abilities, but they also have few avenues to use spared abilities. This investigation characterized the communication environments of three severely aphasic nursing home residents by determining their interactants (i.e., people with whom they interacted), where interactions took place, what information content was communicated in these interactions, and why this communication occurred. Data collection relied on direct observation of the aphasic individuals in their daily living environments and semi-structured interviews with their interactants. Findings revealed that all three aphasic individuals interacted with a wide variety of people, from those one would expect, such as nurses, to those who are not so obvious, such as hairdressers and maintenance staff members. The majority of communication occurred with Certified Nursing Assistants (CNAs). With respect to communication locations, most communication occurred either in the aphasic individuals' own rooms, in their dining rooms, or in the hallways of their nursing homes. Communication content was categorized as either Social Communication, Activities of Daily Living (ADL) Communication, Medical and Physical Well-being Communication, and Facility Survival Skills Communication. For all three aphasic individuals, Social Communication and ADL Communication were the primary topic areas. To answer the question of why communication occurred, interactions were characterized as either instrumental (task-based) or affective (socially-based). The aphasic individuals varied in the ratios of these two types of communication. Possible contributing factors to the different profiles included the length of time each individual had to adapt to both the sequelae of his or her stroke and his or her nursing home environs, as well as individual personality characteristics. Clinical implications from the findings are suggested.

No description available.

Two experiments studied the effectiveness of Imitation and Listener Uncertainty as speech training techniques for profoundly hearing-impaired children. In the first study, a single-subject design was employed with two children who were trained on /$ int$/ and /r/ in words using alternating treatments. Results showed short term benefits for both treatments, but better retention and better generalization to spontaneous speech for the Listener Uncertainty approach. In the second study, 33 children were matched as closely as possible and randomly assigned to the Imitation Group, Listener Uncertainty Group or Control Group. Students in the treatment groups were trained on fricatives in words, phrases and sentences. Plosives were used as control phonemes. Results indicated significant improvement on production of trained and untrained words for both treatments, with higher scores for Listener Uncertainty. However, there was no difference between the treatment groups and control group on ability to generalize target sounds to spontaneous speech. Effects of context and phoneme position were also examined.