A Beamformer Analysis of MEG Data Reveals Frontal Generators of the Musically Elicited Mismatch Negativity

Claudia Lappe,Christo Pantev,Olaf Steinsträter,Trevor Bruce Penney

doi:10.1371/journal.pone.0061296

Claudia Lappe, Christo Pantev + Show 2 more

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https://doi.org/10.1371/journal.pone.0061296

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Abstract

To localize the neural generators of the musically elicited mismatch negativity with high temporal resolution we conducted a beamformer analysis (Synthetic Aperture Magnetometry, SAM) on magnetoencephalography (MEG) data from a previous musical mismatch study. The stimuli consisted of a six-tone melodic sequence comprising broken chords in C- and G-major. The musical sequence was presented within an oddball paradigm in which the last tone was lowered occasionally (20%) by a minor third. The beamforming analysis revealed significant right hemispheric neural activation in the superior temporal (STC), inferior frontal (IFC), superior frontal (SFC) and orbitofrontal (OFC) cortices within a time window of 100–200 ms after the occurrence of a deviant tone. IFC and SFC activation was also observed in the left hemisphere. The pronounced early right inferior frontal activation of the auditory mismatch negativity has not been shown in MEG studies so far. The activation in STC and IFC is consistent with earlier electroencephalography (EEG), optical imaging and functional magnetic resonance imaging (fMRI) studies that reveal the auditory and inferior frontal cortices as main generators of the auditory MMN. The observed right hemispheric IFC is also in line with some previous music studies showing similar activation patterns after harmonic syntactic violations. The results demonstrate that a deviant tone within a musical sequence recruits immediately a distributed neural network in frontal and prefrontal areas suggesting that top-down processes are involved when expectation violation occurs within well-known stimuli.

Highlights

The auditory mismatch negativity is an event-related brain response elicited after an acoustic change within a repetitive regular auditory stimulation
We addressed the MMN localization problem by analyzing a dataset from a previous event related potential (ERP) musical mismatch study [12] in which participants, who had no prior formal musical training, received 2 weeks of piano training while their musical mismatch negativity was tested before and after the training
Significant neural activation was found in both time intervals and in both hemispheres

Summary

Introduction

The auditory mismatch negativity is an event-related brain response elicited after an acoustic change within a repetitive regular auditory stimulation. Since the MMN is elicited even in the absence of attention to the sound stimuli, it is assumed that it reflects a preattentive mechanism for auditory change detection [2,3] It is, a widely adopted model that the presentation of a standard auditory stimulus leads to a learned regularity which serves as a top-down cue which is used to predict and evaluate bottom-up auditory inputs [4,5,6]. Improvement in tone discrimination ability resulting from systematic learning leads to an increment of the MMN component. This phenomenon is illustrated by short musical melodies that elicit an MMN after an infrequently occurring deviant musical tone. Expectancy violation within a musical context may occur because representations of musical structure and tonal progression already exist in our long-term memory [15]

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