The overall goal of this project is to identify the neural correlates of treatment-induced recovery of phonology in individuals with chronic aphasia. Deficits in phonology (speech sound processing) are among the most common and persistent impairments in aphasia after left hemisphere stroke, and can have significant functional consequences for spoken and written language. These deficits are typically treated with behavioral therapy involving targeted activities that encourage brain reorganization to support relearning of language skills. While many individuals make considerable gains through treatment, the neural substrates supporting these improvements are poorly understood. Specifically, it is not clear how improved phonological skills are supported when highly specialized left-hemisphere persiylvian language regions are damaged. To address this question, I propose to study changes in regional brain activation associated with a phonological task (pseudoword reading) performed during functional magnetic resonance imaging (fMRI) before and after phonological treatment. Using a case series design across eight individuals who experienced left middle cerebral artery stroke, I will study response accuracy and fMRI activation during pseudoword reading over the course of four scanning sessions (2 before and 2 after treatment). Behavioral improvement in pseudoword reading will be validated by comparison with clinical data collected before, during, and after treatment. The evidence-based treatment protocol will be implemented as part of an ongoing research project (R01DC07646- 09 awarded to the faculty sponsor), lasting approximately fourteen weeks. Differences in pre-post treatment brain activation evoked by the pseudoword reading task will be considered an effect of therapy. It is hypothesized that improvements in pseudoword reading will be associated with reliance on the undamaged (i.e. residual) left persiylvian regions of the language network and perilesional tissue. It is also predicted that a successful treatment response will require increased engagement of attentional resources to support task performance, and this should be evident by increased activation of a bi-hemispheric fronto-parietal network dorsal to the perisylvian language region. The findings from this study are expected to provide a better understanding of the neural mechanisms that support language recovery, and have the potential to inform treatment approaches for aphasia. 1
With one million Americans currently living with aphasia and 80,000 new cases each year, aphasia is one of the most common and debilitating results of left-hemisphere stroke. Aphasia severely impacts quality of life and emotional well-being by limiting social engagement, family involvement, occupational livelihood, and other areas of life participation. Research that clarifies how the brain supports improved language function through speech-language therapy will lead to a better understanding of how neural factors relate to success in treatment and in the long-term assist in the development and evaluation of treatments to maximize language recovery. 1
| DeMarco, Andrew T; Wilson, Stephen M; Rising, Kindle et al. (2018) The neural substrates of improved phonological processing following successful treatment in a case of phonological alexia and agraphia. Neurocase 24:31-40 |
| DeMarco, Andrew T; Wilson, Stephen M; Rising, Kindle et al. (2017) Neural substrates of sublexical processing for spelling. Brain Lang 164:118-128 |
| Bonakdarpour, B; Beeson, P M; DeMarco, A T et al. (2015) Variability in blood oxygen level dependent (BOLD) signal in patients with stroke-induced and primary progressive aphasia. Neuroimage Clin 8:87-94 |
