Gamma band pitch responses in human auditory cortex measured with magnetoencephalography

William Sedley,Timothy D Griffiths,Sukhbinder Kumar,Gareth R Barnes,Sundeep Teki,Tobias Overath

doi:10.1016/j.neuroimage.2011.08.098

Abstract

We have previously used direct electrode recordings in two human subjects to identify neural correlates of the perception of pitch (Griffiths, Kumar, Sedley et al., Direct recordings of pitch responses from human auditory cortex, Curr. Biol. 22 (2010), pp. 1128–1132). The present study was carried out to assess virtual-electrode measures of pitch perception based on non-invasive magnetoencephalography (MEG). We recorded pitch responses in 13 healthy volunteers using a passive listening paradigm and the same pitch-evoking stimuli (regular interval noise; RIN) as in the previous study. Source activity was reconstructed using a beamformer approach, which was used to place virtual electrodes in auditory cortex. Time-frequency decomposition of these data revealed oscillatory responses to pitch in the gamma frequency band to occur, in Heschl's gyrus, from 60 Hz upwards. Direct comparison of these pitch responses to the previous depth electrode recordings shows a striking congruence in terms of spectrotemporal profile and anatomical distribution. These findings provide further support that auditory high gamma oscillations occur in association with RIN pitch stimuli, and validate the use of MEG to assess neural correlates of normal and abnormal pitch perception.

Highlights

Pitch is a perceptual property of sound that has a complex relationship to the temporal and spectral properties of acoustic stimuli (de Cheveigné, 2005)
Non-invasive recording of human brain activity using magnetoencephalography (MEG; Krumbholz et al, 2003) has shown evoked activity during the presentation of regular stimuli associated with pitch; source localisation of this activity implicates similar areas in the medial part of Heschl's gyrus (HG) to those from which the direct recordings were made (Griffiths et al, 2010)
Most Equivalent current dipoles (ECDs) were located in auditory cortex, either HG or PT, the group means were at the border of mid HG and PT, and no consistent difference was seen between the noise onset and regular interval noise (RIN) transition dipole locations

Summary

Introduction

Pitch is a perceptual property of sound that has a complex relationship to the temporal and spectral properties of acoustic stimuli (de Cheveigné, 2005). Studies of animal and human cortex have examined temporal and spectral sensory representation relevant to pitch and neural correlates of the pitch percept itself. With respect to the latter, these studies have examined the possible existence of a ‘pitch centre’ in auditory cortex where neural activity corresponds to the perceived pitch irrespective of the stimulus with which it is associated, analogous to the concept of a ‘colour centre’ in the visual system (Zeki, 1980). Non-invasive recording of human brain activity using magnetoencephalography (MEG; Krumbholz et al, 2003) has shown evoked activity during the presentation of regular stimuli associated with pitch; source localisation of this activity implicates similar areas in the medial part of Heschl's gyrus (HG) to those from which the direct recordings were made (Griffiths et al, 2010)

Objectives

Methods

Results

Conclusion