Exploring the Role of Central Auditory Processing in Spoken Language Comprehension in Aphasia after Stroke

About This Grant

Two million Americans—100,000 of whom are Veterans—are living with aphasia, a debilitating communication disorder most commonly caused by stroke. Impaired spoken language comprehension in aphasia has a negative impact on functional outcomes, yet deficits are difficult to treat and there are few efficacious therapy options. One key challenge to rehabilitating spoken language comprehension in aphasia is lack of a mechanistic framework to explain performance. In particular, the role of central auditory processing— a skill critical for spoken language comprehension in other neurological conditions—remains unclear. The goal of this career development award (CDA-1) is to elucidate the role of central auditory processing in spoken language comprehension in aphasia after stroke. We will assess 30 people with chronic aphasia and 30 matched controls using an extensive battery of behavioral and electrophysiological tests. Clinical neuroimaging will also be obtained. Findings will be analyzed using Bayesian multiple linear regression to quantify between-group differences and investigate within-group variation at both behavioral and neural levels. In Aim 1, we will evaluate the unique effect of central auditory processing on spoken language comprehension in aphasia. First, we will quantify differences in performance on a range of speech perception tests in people with aphasia and matched controls. Then, we will evaluate the extent to which performance on the speech perception tests uniquely predicts spoken language comprehension in the aphasia group. Critically, behavioral performance on language and cognitive testing will be included as controlling covariates to account for their known contributions to spoken language comprehension in aphasia. In Aim 2, we will characterize the neural correlates of central auditory processing in aphasia. First, we will quantify differences in latencies and amplitudes from two auditory event-related potentials (N200, P300) in people with aphasia and matched controls. Then, we will evaluate the extent to which performance on the speech perception tests are associated with N200/P300 amplitudes and latencies, and structural damage to key left hemisphere regions in the aphasia group. As with Aim 1, behavioral performance on language and cognitive testing will be controlled for in our analyses. The impact of this CDA-1 will be a brain-behavior framework of spoken language comprehension in aphasia that considers all relevant processes (cognitive, linguistic, central auditory). This framework will allow us to develop novel clinical diagnostic tools and behavioral interventions, the latter of which will be targeted in a CDA-2 proposal. Moreover, this award will support the applicant—a speech-language pathologist with expertise in aphasia and neuroscience—in obtaining auditory research training at the Veterans Affairs National Center for Rehabilitative Auditory Research and developing an independent research program there.