Investigations into the role of early visual cortex in expertise reading musical notation

This dissertation aims at investigating the role of early visual cortex in music reading expertise. This work was motivated by the surprising finding of neural selectivity for musical notes in early visual cortex with music reading expertise, which is not predicted by current theories about the role of early visual cortex in object recognition or in perceptual expertise. In this dissertation, I investigated the mechanisms underlying the recruitment of early visual cortex for musical notes by examining the temporal dynamics of the neural selectivity for musical notation using scalp electrophysiological recordings. I found that expertise effects for musical notes could be observed as early as 40--60ms after stimulus onset, suggesting that the initial visual processes for notes have been altered with experience in music reading. This early selectivity for notes is predicted by degrees of crowding and holistic processing within music reading experts, supporting the functional significance of this early effect. These results imply that the recruitment of the early visual cortex is, at least partially, a feedforward effect, and suggest that early visual cells become selective for musical notes with the acquisition of music reading expertise.;This dissertation begins (CHAPTER I) with a review of perceptual expertise studies and my previous work in music reading that motivated this dissertation work. Then I discuss current views on the role of early visual cortex in object recognition and perceptual expertise, followed by describing two possible mechanisms underlying the recruitment of early visual cortex for musical notes, and how temporal dynamics of the neural selectivity for notes can help to tease apart these two possibilities. After that, I briefly review the literature on crowding, which served as behavioral correlates for the ERP effects.;CHAPTER II reports the methods and results of the ERP experiment. Music reading experts and novices were recruited and performed a simple one-back task with musical notes, letters or pseudo-letters, with a design following that of the prior fMRI study. I observed ERP expertise effects for musical notation with various ERP components, including the C1 component bilaterally (40--60ms), the N170 component bilaterally (120--200ms), and the CNV component (-200--0ms).;Next, I describe the study on crowding and music reading expertise (CHAPTER III). I found that experts experienced less crowding for musical stimuli but not for non-musical novel stimuli (Landolt C). Correlation analyses in CHAPTER IV revealed the behavioral significance of the expertise effects obtained with the C1, N170 and CNV components. Both the C1 and N170 expertise effects were predicted by all behavioral measures, including music reading ability (measured by perceptual fluency), crowding and holistic processing, while the CNV expertise effect was predicted by perceptual fluency and crowding.;I conclude my dissertation with CHAPTER V, in which I discuss the implications of the expertise effects obtained with various ERP components and crowding, including the role of early visual cortex in music reading expertise, and general implications on studies in perceptual expertise, object recognition and visual crowding.