Musicians demonstrate experience-dependent brainstem enhancement of musical scale features within continuously gliding pitch

Abstract

In contrast to language, where pitch patterns consist of continuous and curvilinear contours, musical pitch consists of relatively discrete, stair-stepped sequences of notes. Behavioral and neurophysiological studies suggest that both tone-language and music experience enhance the representation of pitch cues associated with a listener's domain of expertise, e.g., curvilinear pitch in language, discrete scale steps in music. We compared brainstem frequency-following responses (FFRs) of English-speaking musicians (musical pitch experience) and native speakers of Mandarin Chinese (linguistic pitch experience) elicited by rising and falling tonal sweeps that are exemplary of Mandarin tonal contours but uncharacteristic of the pitch patterns typically found in music. In spite of musicians' unfamiliarity with such glides, we find that their brainstem FFRs show enhancement of the stimulus where the curvilinear sweep traverses discrete notes along the diatonic musical scale. This enhancement was note specific in that it was not observed immediately preceding or following the scale tone of interest (passing note). No such enhancements were observed in Chinese listeners. These findings suggest that the musician's brainstem may be differentially tuned by long-term exposure to the pitch patterns inherent to music, extracting pitch in relation to a fixed, hierarchical scale.

Figure 1

Fundamental frequency (F0) contours of the stimuli. Each condition represents a continuous pitch sweep uncharacteristic of prototypical musical pitch patterns, which are typically discrete and stair-stepped. Compared to the standard (STD) condition, UP is transposed upward by two semitones, whereas DOWN represents a mirrored version which descends in pitch. All three F0 contours span a major third in either the ascending (DO-RE-MI) or descending (MI-RE-DO) direction. Analysis segments of interest (Pre, On, Post) are demarcated along the trajectory of each contour.

Figure 2

Group comparisons of FFR response properties for the standard (STD) condition. (A) FFR waveforms of a representative subject from each group. Relative to Chinese, musician FFR time waveforms show more robust periodicity encoding of the tonal sweep during the musical passing tone (On segment) but not immediately preceding (Pre) or following (Post) this musical event. (B) Response spectra (FFTs) computed in each time segment per group. Note the selective enhancement of F0 (~110 Hz) for musicians, relative to Chinese, during the On segment (i.e., the passing tone). No group differences in F0 magnitude are observed immediately preceding (Pre) or following (Post) this musical event.

Figure 3

Group comparisons of brainstem “pitch” encoding computed from FFRs. F0 magnitudes are shown for segments within the response before (Pre), during (On), and after (Post) the location of the passing tone for the (A) standard (STD), (B) UP, and (C) DOWN tonal sweeps (see Fig. 1). Despite their continuous nature, musicians show enhanced encoding, relative to Chinese, in that portion of the stimulus contour localized to this prominent musical event (i.e., RE). Error bars = ±1 SE.