Date of Award

5-2012

Document Type

Dissertation

Degree Name

Doctor of Science (ScD)

College/School

College of Humanities and Social Sciences

Department/Program

Communication Sciences and Disorders

Thesis Sponsor/Dissertation Chair/Project Chair

Ilse J.A. Wambacq

Committee Member

Joan Besing

Committee Member

Martha Anne Ellis

Subject(s)

Auditory pathways, Ear--Physiology

Abstract

When a sound is heard, individuals intrinsically attempt to identify the sound and its location. This automatic and parallel processing is known as the auditory “what” and “where” pathways. The present study involved the neurophysiologic investigation of the auditory dual pathways in an attention and working memory task as a function of age. Using identical stimuli, event-related potentials were measured in young and middle-aged adults with normal hearing for both pitch identification (“what” pathway) and location (“where” pathway). Results showed differences in cortical processing of the “what” and “where” pathways as a function of age and task instruction. Although processing differences of the “what” and “where” pathways have been reported, this study investigated early age-related changes in the auditory dual pathways. In the attention task, young adults displayed increased P3 amplitude for the “what” compared to “where” pathway. On the contrary, middle-age participants displayed similar P3 amplitudes for both the “what” and “where” tasks. In the working memory task, middle-aged adults displayed greater reliance on working memory (as evidenced by increased sustained frontal negativity) in the “what” compared to “where” pathway while young adults showed equal processing effort. Our findings indicate the “what” pathway is more sensitive to age-related changes than the “where” pathway.

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