Relationships between behavior, brainstem and cortical encoding of seen and heard speech in musicians and non-musicians

Abstract

Musicians have a variety of perceptual and cortical specializations compared to non-musicians. Recent studies have shown that potentials evoked from primarily brainstem structures are enhanced in musicians, compared to non-musicians. Specifically, musicians have more robust representations of pitch periodicity and faster neural timing to sound onset when listening to sounds or both listening to and viewing a speaker. However, it is not known whether musician-related enhancements at the subcortical level are correlated with specializations in the cortex. Does musical training shape the auditory system in a coordinated manner or in disparate ways at cortical and subcortical levels? To answer this question, we recorded simultaneous brainstem and cortical evoked responses in musician and non-musician subjects. Brainstem response periodicity was related to early cortical response timing across all subjects, and this relationship was stronger in musicians. Peaks of the brainstem response evoked by sound onset and timbre cues were also related to cortical timing. Neurophysiological measures at both levels correlated with musical skill scores across all subjects. In addition, brainstem and cortical measures correlated with the age musicians began their training and the years of musical practice. Taken together, these data imply that neural representations of pitch, timing and timbre cues and cortical response timing are shaped in a coordinated manner, and indicate corticofugal modulation of subcortical afferent circuitry.

Music training alters the course of adolescent auditory development

“…This process is not complete until young adulthood, by which time N1 has become the largest component in the cortical response to sound (17,18,(21)(22)(23). In adults, music training amplifies the N1 response (53)(54)(55)(56). Here, we find an increase in N1 amplitude relative to P1 amplitude only in the music group.…”

“…These enhancements extend to the subcortical auditory system, with musicians showing responses to sound that are faster (55,(57)(58)(59)(60)(61), are degraded less by background noise (32,61), represent speech formant structure more robustly (32,(62)(63)(64). differentiate speech sounds to a greater extent (65)(66)(67), track stimulus pitch more accurately (68,69), and are more consistent across trials (59,70).…”

Audiovisual Deficits in Older Adults with Hearing Loss: Biological Evidence

“…Auditory experts, such as musicians, lie on the opposite end of the perceptual spectrum from individuals with HL. Lifelong music training has been given to enhance both auditory and AV processing (Zatorre 1998;Gaser & Schlaug 2003;Wong et al 2007;Musacchia et al 2007Musacchia et al , 2008Zatorre et al 2007). In our previous study, auditory and AV speech tokens elicited larger and earlier P1 and N1 peaks in musicians than in nonmusician controls (Musacchia et al 2008).…”

“…Lifelong music training has been given to enhance both auditory and AV processing (Zatorre 1998;Gaser & Schlaug 2003;Wong et al 2007;Musacchia et al 2007Musacchia et al , 2008Zatorre et al 2007). In our previous study, auditory and AV speech tokens elicited larger and earlier P1 and N1 peaks in musicians than in nonmusician controls (Musacchia et al 2008). Although a direct continuum cannot be drawn between the integration mechanisms of "auditory expertise" and hearing impairment, it is interesting to note that the musicians in our previous study and HLs in the current one show effects at the same peaks.…”

“…The slope between peaks P1 and N1 was computed to create a composite measure of early response strength. As in our previous publications (Russo et al 2004;Musacchia et al 2008), this measure is used to assess the synchrony of positive to negative deflection in successive cortical peaks. …”