The Nature and Origins of Selectivity for Music in the Human Brain

Abstract

Music is uniquely and universally human, and arises early in development. Recent fMRI studies have revealed neural populations in non-primary auditory cortex that respond selectively to music, responding strongly to a wide variety of music sounds, but much less strongly to non-musical synthetic sounds with similar acoustic properties or to other real-world sounds. While these findings represent a significant advance, many fundamental questions about cortical music selectivity remain unanswered. What feature(s) of music elicit the observed music-selective neural responses? What stimulus timescales are music-selective responses sensitive to, and how do these compare to the timescales underlying speech-selective responses? Finally, how do these neural mechanisms for music arise, and what is the role of experience in their development? To address these questions, we measured participants’ fMRI responses to a large number of real-world sounds and used voxel decomposition methods to isolate a music-selective component of auditory cortical responses. We then estimated the component’s response to new stimulus conditions to test various aspects of music selectivity. We found that the music-selective component integrated information on the timescale of several hundreds of milliseconds, and that its response reflected both the pitch and temporal structure of music. This sensitivity to musical structure was specific to the music component, and was not present even in spatially overlapping response components with other selectivities. We also found that this music-selective component of auditory cortical responses was clearly present in people without musical training, demonstrating that it is a general property of human brains, not a consequence of formal training. The results of this thesis answer basic questions about how the brain processes musical sounds, and advance our understanding of the underlying computations and mechanisms at play in non-primary auditory cortex.