Neural responses to sounds presented on and off the beat of ecologically valid music

Adam Tierney,Nina Kraus

doi:10.3389/fnsys.2013.00014

Abstract

The tracking of rhythmic structure is a vital component of speech and music perception. It is known that sequences of identical sounds can give rise to the percept of alternating strong and weak sounds, and that this percept is linked to enhanced cortical and oscillatory responses. The neural correlates of the perception of rhythm elicited by ecologically valid, complex stimuli, however, remain unexplored. Here we report the effects of a stimulus' alignment with the beat on the brain's processing of sound. Human subjects listened to short popular music pieces while simultaneously hearing a target sound. Cortical and brainstem electrophysiological onset responses to the sound were enhanced when it was presented on the beat of the music, as opposed to shifted away from it. Moreover, the size of the effect of alignment with the beat on the cortical response correlated strongly with the ability to tap to a beat, suggesting that the ability to synchronize to the beat of simple isochronous stimuli and the ability to track the beat of complex, ecologically valid stimuli may rely on overlapping neural resources. These results suggest that the perception of musical rhythm may have robust effects on processing throughout the auditory system.

Highlights

One of the fundamental characteristics underlying speech and music is organization in time
We found that onset responses to the target sound in both the cortex and the brainstem were enhanced by alignment with the musical beat
This enhancement may stem from phase-locking of ongoing oscillations within auditory cortex and the brainstem to the beat of the music (Large, 2008), decreasing the threshold for firing at beat onsets

Summary

Introduction

One of the fundamental characteristics underlying speech and music is organization in time. Phase-locking of neuronal oscillations to slow rhythms in speech and music may lead to alternating periods of greater and lesser salience (Large and Jones, 1999), as the phase of neural oscillations within the 2–6 Hz range has been linked to acoustic target detection (Ng et al, 2012) and both auditory and visual perceptual processing are enhanced when stimuli are aligned with musical beats (Jones et al, 2002; Escoffier et al, 2010). Stimuli presented at times aligned with a perceived musical beat may, lead to greater firing rates and evoked electrophysiological potentials. Difficulty tracking slow temporal patterns has been suggested as a potential cause underlying language impairment (Abrams et al, 2009; Goswami, 2011)

Objectives

Methods

Results

Conclusion