Date of Award

Summer 2021

Document Type

Open Access Dissertation

Department

Communication Sciences and Disorders

First Advisor

Julius Fridriksson

Abstract

Neural synchrony across listeners during language processing has been found to be associated with successful comprehension in neurotypical adults. At initial presentation of auditory-visual stimuli, neural responses appear to oscillate in different rhythms across brain regions. As the stimulus progresses, the time course of neural activity synchronizes across listeners, particularly in primary auditory and visual processing regions. This phenomenon, which we refer to as ‘neural entrainment,’ has been observed in neurotypical individuals attending to the same stimulus. Neural synchrony occurs due to the inherent neural response elicited by a stimulus and has been shown to be consistent across participants in specific regions when attending to the same, time-locked stimulus. In persons with aphasia, language comprehension is often impaired, resulting in differing degrees of comprehension deficits depending on the size and location of one’s lesion. One way to explain such comprehension deficits may be a lack of neural coupling across language processing regions during naturalistic comprehension, likely caused by lesion damage.

The present study investigated neural synchrony among participants with aphasia compared to neurotypical controls attending to the same naturalistic stimulus. Regions that showed significant synchrony in the control group were selected as seed regions of interest and were examined further in participants with aphasia to investigate behavioral correlates. Results indicate that individuals with aphasia do not synchronize in in-tact brain regions, and there is evidence that region-specific synchrony is associated with comprehension scores particularly in right hemisphere ventral stream regions and left posterior temporal regions.

The present study provides evidence that naturalistic synchrony can explain some degree of the integrity of residual regions and regional synchrony is associated with off-line comprehension ability.

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