Sensorimotor processing of auditory feedback in aphasia

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PROJECT SUMMARY/ABSTRACT Stroke is a leading cause of disability in the United States, which in many cases can lead to speech impairment that creates barriers to participation in professional, social, and family settings. Aphasia is the most common type of post-stroke speech impairment that has profound consequences for the patients and results in diminished ability to comprehend, produce and control speech. While recovery can be promoted with speech treatment, improvement remains modest and typically requires a large amount of therapy which contributes to rising health care costs. A major shortcoming of currently existing treatment approaches is that they have focused on enhancing the outcome measures associated speech production, without taking into account that targeting deficits in sensory feedback processing of speech may significantly increase treatment efficiency and effectiveness. Therefore, a key step toward refining treatment strategies is to develop objective biomarkers that can probe the integrity of sensorimotor mechanisms of speech and identify their impaired function in patients with post-stroke aphasia. This proposed project is significant because it takes the first step toward exploring the behavioral and neuroanatomical biomarkers of impaired sensorimotor processing, with focus on understanding the critical role of auditory feedback mechanisms for speech production in aphasia. The career development plan combines the candidate's former research training with expertise of the mentoring team to meet the goals of the proposed project. The research and training plans provide an empirical foundation for the proposed project and will allow the candidate to establish a translational line of research as an independent investigator to study the behavioral and neural bases of speech sensorimotor impairment in stroke patients with aphasia. This project aims to use the behavioral biomarkers of altered auditory feedback (AAF) combined with neuroimaging data to identify the patterns of brain damage and diminished structural connectivity within the auditory-motor areas of the left hemisphere that predict impaired sensorimotor processing of speech in aphasia. The long-term goal of this research is to develop a model that relates patterns of brain damage to sensorimotor deficits causing speech impairment. The main objective of this proposal is to identify behavioral and neuroanatomical biomarkers that characterize deficits in sensorimotor mechanisms of speech. The central hypothesis is that damages to auditory-motor network will impair speakers' ability to detect and/or correct for AAF-induced speech errors. We also hypothesize that the patterns of damage will predict the degree of diminished speech error processing, as indexed by the AAF biomarkers. The rationale for the proposed research is that identifying the source of sensorimotor deficit will improve diagnosis and targeted treatment of speech disorders in aphasia. The proposed research is relevant to that part of NIH's mission that pertains to developing fundamental knowledge that will potentially help to reduce the burdens of human disability.