Limits...
Multi-Variate EEG Analysis as a Novel Tool to Examine Brain Responses to Naturalistic Music Stimuli.

Sturm I, Dähne S, Blankertz B, Curio G - PLoS ONE (2015)

Bottom Line: We demonstrate that a significant CACor (i) can be detected in an individual listener's EEG of a single presentation of a full-length complex naturalistic music stimulus, and (ii) it co-varies with the stimuli's average magnitudes of sharpness, spectral centroid, and rhythmic complexity.In particular, the subset of stimuli eliciting a strong CACor also produces strongly coordinated tension ratings obtained from an independent listener group in a separate behavioral experiment.Thus musical features that lead to a marked physiological reflection of tone onsets also contribute to perceived tension in music.

View Article: PubMed Central - PubMed

Affiliation: Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Berlin, Germany; Neurotechnology Group, Technische Universität Berlin, Berlin, Germany; Neurophysics Group, Department of Neurology, Charité University Medicine, Berlin, Germany.

ABSTRACT
Note onsets in music are acoustic landmarks providing auditory cues that underlie the perception of more complex phenomena such as beat, rhythm, and meter. For naturalistic ongoing sounds a detailed view on the neural representation of onset structure is hard to obtain, since, typically, stimulus-related EEG signatures are derived by averaging a high number of identical stimulus presentations. Here, we propose a novel multivariate regression-based method extracting onset-related brain responses from the ongoing EEG. We analyse EEG recordings of nine subjects who passively listened to stimuli from various sound categories encompassing simple tone sequences, full-length romantic piano pieces and natural (non-music) soundscapes. The regression approach reduces the 61-channel EEG to one time course optimally reflecting note onsets. The neural signatures derived by this procedure indeed resemble canonical onset-related ERPs, such as the N1-P2 complex. This EEG projection was then utilized to determine the Cortico-Acoustic Correlation (CACor), a measure of synchronization between EEG signal and stimulus. We demonstrate that a significant CACor (i) can be detected in an individual listener's EEG of a single presentation of a full-length complex naturalistic music stimulus, and (ii) it co-varies with the stimuli's average magnitudes of sharpness, spectral centroid, and rhythmic complexity. In particular, the subset of stimuli eliciting a strong CACor also produces strongly coordinated tension ratings obtained from an independent listener group in a separate behavioral experiment. Thus musical features that lead to a marked physiological reflection of tone onsets also contribute to perceived tension in music.

No MeSH data available.


Related in: MedlinePlus

Table of CACor coefficients.CACor coefficients for each single subject and each stimulus presentation; GA: Grand Average (N = 27). Pink shading indicates significant positive correlation between EEG projection and audio power slope. Significance was determined by applying permutation tests and subsequently performing Bonferroni-correction for N = 27 presentations per stimulus.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4624980&req=5

pone.0141281.g004: Table of CACor coefficients.CACor coefficients for each single subject and each stimulus presentation; GA: Grand Average (N = 27). Pink shading indicates significant positive correlation between EEG projection and audio power slope. Significance was determined by applying permutation tests and subsequently performing Bonferroni-correction for N = 27 presentations per stimulus.

Mentions: The table depicted in Fig 4 gives CACor coefficients for each single subject and each stimulus presentation. The bottom line of each table contains the correlation coefficient for the Grand Average EEG projection (average of the 27 EEG projections for each stimulus). Note that correlation coefficients cannot be compared between stimuli, since duration and autocorrelation properties differ between stimuli. Shaded cells indicate significant correlation at the level of alpha = 0.05. Significance was determined by applying permutation tests and subsequently correcting for the number of 27 presentations per stimulus (see Methods, Subsection ‘Significance of Correlation‘). Stimuli were ordered according to the total number of presentations with significant CACor (called CACor score in the following). Since these were derived in a cross-validation approach (see Methods, Subsection ‘EEG analysis: Calculating Cortico-Acoustic Correlation‘) significant correlation coefficients can be regarded as reflecting a genuine influence of the stimulus on brain responses that generalize across several presentations of a stimulus. To give an impression of the extracted EEG projections and their relation to the audio power slope three examples are shown in Fig 5. Fig 6A summarizes the corresponding CACor scores into a CACor score profile for the set of nine stimuli. For comparison, both, the CACor score profile that was derived by applying permutation tests (dark blue bars), and that derived by applying Pyper et al.’s method [53] to assess the significance of correlation in signals containing serial autocorrelation (light blue bars) are given. Although there are differences in the absolute CACor scores for both methods, the ranking of the stimuli does not change. Importantly, the comparison shows that the zero scores for Orchestra and Jungle indicate an absence of significant CACor for these stimuli and are not introduced by the permutation test approach. In the following the profile derived by permutation tests is used for further analysis.


Multi-Variate EEG Analysis as a Novel Tool to Examine Brain Responses to Naturalistic Music Stimuli.

Sturm I, Dähne S, Blankertz B, Curio G - PLoS ONE (2015)

Table of CACor coefficients.CACor coefficients for each single subject and each stimulus presentation; GA: Grand Average (N = 27). Pink shading indicates significant positive correlation between EEG projection and audio power slope. Significance was determined by applying permutation tests and subsequently performing Bonferroni-correction for N = 27 presentations per stimulus.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4624980&req=5

pone.0141281.g004: Table of CACor coefficients.CACor coefficients for each single subject and each stimulus presentation; GA: Grand Average (N = 27). Pink shading indicates significant positive correlation between EEG projection and audio power slope. Significance was determined by applying permutation tests and subsequently performing Bonferroni-correction for N = 27 presentations per stimulus.
Mentions: The table depicted in Fig 4 gives CACor coefficients for each single subject and each stimulus presentation. The bottom line of each table contains the correlation coefficient for the Grand Average EEG projection (average of the 27 EEG projections for each stimulus). Note that correlation coefficients cannot be compared between stimuli, since duration and autocorrelation properties differ between stimuli. Shaded cells indicate significant correlation at the level of alpha = 0.05. Significance was determined by applying permutation tests and subsequently correcting for the number of 27 presentations per stimulus (see Methods, Subsection ‘Significance of Correlation‘). Stimuli were ordered according to the total number of presentations with significant CACor (called CACor score in the following). Since these were derived in a cross-validation approach (see Methods, Subsection ‘EEG analysis: Calculating Cortico-Acoustic Correlation‘) significant correlation coefficients can be regarded as reflecting a genuine influence of the stimulus on brain responses that generalize across several presentations of a stimulus. To give an impression of the extracted EEG projections and their relation to the audio power slope three examples are shown in Fig 5. Fig 6A summarizes the corresponding CACor scores into a CACor score profile for the set of nine stimuli. For comparison, both, the CACor score profile that was derived by applying permutation tests (dark blue bars), and that derived by applying Pyper et al.’s method [53] to assess the significance of correlation in signals containing serial autocorrelation (light blue bars) are given. Although there are differences in the absolute CACor scores for both methods, the ranking of the stimuli does not change. Importantly, the comparison shows that the zero scores for Orchestra and Jungle indicate an absence of significant CACor for these stimuli and are not introduced by the permutation test approach. In the following the profile derived by permutation tests is used for further analysis.

Bottom Line: We demonstrate that a significant CACor (i) can be detected in an individual listener's EEG of a single presentation of a full-length complex naturalistic music stimulus, and (ii) it co-varies with the stimuli's average magnitudes of sharpness, spectral centroid, and rhythmic complexity.In particular, the subset of stimuli eliciting a strong CACor also produces strongly coordinated tension ratings obtained from an independent listener group in a separate behavioral experiment.Thus musical features that lead to a marked physiological reflection of tone onsets also contribute to perceived tension in music.

View Article: PubMed Central - PubMed

Affiliation: Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Berlin, Germany; Neurotechnology Group, Technische Universität Berlin, Berlin, Germany; Neurophysics Group, Department of Neurology, Charité University Medicine, Berlin, Germany.

ABSTRACT
Note onsets in music are acoustic landmarks providing auditory cues that underlie the perception of more complex phenomena such as beat, rhythm, and meter. For naturalistic ongoing sounds a detailed view on the neural representation of onset structure is hard to obtain, since, typically, stimulus-related EEG signatures are derived by averaging a high number of identical stimulus presentations. Here, we propose a novel multivariate regression-based method extracting onset-related brain responses from the ongoing EEG. We analyse EEG recordings of nine subjects who passively listened to stimuli from various sound categories encompassing simple tone sequences, full-length romantic piano pieces and natural (non-music) soundscapes. The regression approach reduces the 61-channel EEG to one time course optimally reflecting note onsets. The neural signatures derived by this procedure indeed resemble canonical onset-related ERPs, such as the N1-P2 complex. This EEG projection was then utilized to determine the Cortico-Acoustic Correlation (CACor), a measure of synchronization between EEG signal and stimulus. We demonstrate that a significant CACor (i) can be detected in an individual listener's EEG of a single presentation of a full-length complex naturalistic music stimulus, and (ii) it co-varies with the stimuli's average magnitudes of sharpness, spectral centroid, and rhythmic complexity. In particular, the subset of stimuli eliciting a strong CACor also produces strongly coordinated tension ratings obtained from an independent listener group in a separate behavioral experiment. Thus musical features that lead to a marked physiological reflection of tone onsets also contribute to perceived tension in music.

No MeSH data available.


Related in: MedlinePlus