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

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.

Grant Number: 1IK1RX005365-01A1
NIH Institute/Center: VA
Principal Investigator: Marianne Casilio