Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Doctor of Philosophy

Program

Psychology

Supervisor

Grahn, Jessica A.

2nd Supervisor

Owen, Adrian M.

Co-Supervisor

Abstract

Memory for music can be preserved in the presence of neurodegenerative disorders even when other memories are forgotten. However, understanding how the brain remembers music has proven difficult despite decades of research. The central goal of this thesis was to elucidate the neural correlates of musical memory by exploring how the presence of language and music information affect the way young and older adults remember music. To that end, I 1) used a controlled training paradigm to familiarize participants with novel stimuli that manipulated the presence of language and music, and 2) collected functional magnetic resonance imaging data to compare brain activity in response to stimuli that were identical except for their level of familiarity. First, I compared differences in neural activation based on familiarity in young adults using general linear model (GLM) and multivariate pattern analyses (Chapter 2). Contrary to the results of previous studies, there were no differences in the areas involved in processing novel and familiar music. Next, I used an intersubject synchrony analysis to assess the effect of familiarity on neural synchrony (Chapters 3 and 5). Synchrony is a new technique in the musical memory literature that correlates neural activation timecourses to a stimulus across individuals. Familiarity reduced synchrony in both young and older adults. Synchrony reduction is associated with increased idiosyncratic processing across participants. This reduction occurred after a single listen suggesting that each participant had a unique experience of the stimuli after only a single exposure. Finally, I used GLM and synchrony analyses together to characterize how musical stimuli with and without language are processed by healthy young and older adults (Chapter 4). Brain areas involved in processing music and language stimuli differed based on age group and stimuli, but in both groups language information induced more synchrony than stimuli without language. Altogether, these results suggest that 1) similarities in stimulus processing across individuals are directly related to the presence of language, and 2) the lack of clearly defined neural correlates of musical memory across previous studies may stem from the idiosyncrasies in processing that arise as individuals become familiar with musical stimuli.

Summary for Lay Audience

Memory for music is unique in that it may be preserved in the presence of disorders such as dementia even when other memories are forgotten. However, the processes involved in musical memory are not completely understood. In this thesis, I aimed to gain a deeper understanding of how the brain stores musical memories. Specifically, I was interested in how the presence of language affects the way the brain remembers music and whether the mechanisms are similar in young and older adults. To that end, novel musical stimuli with and without language were used in these studies. Participants repeatedly listened to the novel stimuli to become familiar with the music. I used functional magnetic resonance imaging to collect brain activity data while young and older adults listened to the novel and familiar music. I then compared how brain activity changed when listening to identical pieces of music that differed only in their level of familiarity. A variety of analyses were used to investigate the brain areas involved in processing the novel and familiar music as well as the patterns of the fluctuations of the neural activation within those brain areas. Specifically, I characterized the similarity in the patterns of activation in response to the music across participants. The primary findings of this thesis were: 1) in contrast with previous studies, there were no differences in the brain areas involved in processing novel and familiar stimuli in young adults, 2) novel stimuli were processed more similarly than were familiar stimuli by both young and older adults, and 3) music with language was processed more similarly than music without language by participants in both age groups. Overall, the findings of this thesis contribute to the literature on musical memory by expanding existing knowledge on how young and older adults process novel and familiar music. Understanding how the brain processes music has potential implications for the development of therapeutic and clinical interventions that could improve the quality of life for individuals living with dementia.

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