Neural correlates of musical and linguistic pitch as revealed in the auditory brainstem

Gavin M Bidelman, Purdue University

Abstract

Despite notable diversities, all cultures of the world share two unique human faculties: the ability to produce and appreciate aspects of both music and language. To date, studies examining the cognitive neuroscience of these two domains have been restricted primarily to cortical processing and have ignored the potential contribution of subcortical structures to the encoding of musically- and linguistically relevant sound. This dissertation attempts to illuminate these issues by examining three key topics: (1) the neurobiological basis of music; (2) the effects of musical training on subcortical neurophysiological processing; (3) the putative connections between music and language in the brain. Such topics are explored in depth by examining a fundamental auditory attribute common to both the domains of music and language, namely, pitch. Important properties of tonal music (e.g., hierarchical pitch structure, musical key) are appreciated in the absence of rigorous musical experience by both humans and non-humans alike. But is there a neurobiological basis for the architecture of music? In the first part of this dissertation, evidence from evoked potentials, computational modeling, and psychoacoustics is presented which supports the notion that the organizational principles governing musical pitch are rooted in innate, preattentive auditory processing. The question then emerges how long-term experience alters the neural representations for complex acoustic signals (e.g., speech and music). Subcortical brain potentials are compared between musicians and non-musician listeners to examine the effects of musical experience on the neural transcription of music and speech. It is shown that spectro-temporal aspects of these complex signals are enhanced in musically trained individuals thus providing a neurobiological correlate for musicians' perceptual benefits observed in many psychoacoustic tasks. In addition, results indicate that the positive effects of musical training extend beyond the domain of music, tuning brain-behavior mechanisms implicated in language-specific listening. Lastly, connections between music and language processing are examined in an attempt to reveal not only how these two human universals interact but whether or not there are commonalties in their neural representations. Comparisons in perceptual and neurophysiological processing are made between tone language speakers (experienced with linguistic uses of pitch) and musicians (experienced with musical uses of pitch). Results show that pitch encoding enhancements gained from one domain of expertise may transfer to another as long as the latter exhibits acoustic features overlapping those with which an individual has been exposed to through long-term experience or training. Results of this work ultimately suggest that music- and language-dependent operations begin well before the auditory signal reaches cerebral cortex, and moreover, that the auditory pathway is shaped dependent on one's specific auditory experience. Contrary to conventional thought, this work demonstrates that perceptually salient features necessary for high fidelity music and speech perception begin to emerge at preattentive stages of audition.

Degree

Ph.D.

Advisors

Gandour, Purdue University.

Subject Area

Audiology|Neurosciences|Music

COinS