The oscillatory entrainment of virtual pitch perception

Aleksandar Aksentijevic,Mark A Elliott,Anthony Northeast,Daniel Canty

doi:10.3389/fpsyg.2013.00210

Abstract

Evidence suggests that synchronized brain oscillations in the low gamma range (around 33 Hz) are involved in the perceptual integration of harmonic complex tones. This process involves the binding of harmonic components into “harmonic templates” – neural structures responsible for pitch coding in the brain. We investigated the hypothesis that oscillatory harmonic binding promotes a change in pitch perception style from spectral (frequency) to virtual (relational). Using oscillatory priming we asked 24 participants to judge as rapidly as possible, the direction of an ambiguous target with ascending spectral and descending virtual contour. They made significantly more virtual responses when primed at 29, 31, and 33 Hz and when the first target tone was harmonically related to the prime, suggesting that neural synchronization in the low gamma range could facilitate a shift toward virtual pitch processing.

Highlights

Processing the pitch of harmonic complex tones represents one of the most important research topics in auditory perception and cognitive neuroscience (e.g., Patterson et al, 2002; Penagos et al, 2004; Micheyl and Oxenham, 2007; McLachlan, 2011)
Anti-logs of the means of the log-transformed RT distributions were subject to a three-way repeated-measures ANOVA with factors inter-stimulus intervals (ISIs) (100, 400 ms), rate (29, 31, 33, 35, and 37 pps) and target direction (SDVU, SUVD)
The results indicate that Spectral down – virtual up targets (SDVU) targets were processed faster while producing www.frontiersin.org more virtual responses when primed in the low gamma range

Summary

Introduction

Processing the pitch of harmonic complex tones represents one of the most important research topics in auditory perception and cognitive neuroscience (e.g., Patterson et al, 2002; Penagos et al, 2004; Micheyl and Oxenham, 2007; McLachlan, 2011). The fact that a single stimulus can provide two mutually exclusive forms of pitch information (spectral and virtual) offers a convenient way of investigating the dynamics of harmonic pitch integration. Such stimuli consist of pairs of two-frequency tones (see Figure 1). The frequency distance between components increases in the second tone (Smoorenburg, 1970) producing two competing contours – a falling spectral (1A) and a rising virtual (1B) contour. The spectral mode relies on the computation of the frequency differences whereas the virtual mode involves abstraction of tonotopic relationships in the sense that harmonic distance becomes the new unit of information for the purposes of computation and comparison

Methods

Results

Discussion

Conclusion