Abstract

Musical training causes structural and functional changes in the brain due to its sensory-motor demands. This leads to differences in how musicians perceive and process music as compared to nonmusicians, thereby providing insights into brain adaptations and plasticity. Correlational studies and network analysis investigations have indicated the presence of large-scale brain networks involved in the processing of music and have highlighted the differences between musicians and non-musicians. However, studies on functional connectivity in the brain during music listening tasks have thus far focused solely on static network analysis. Dynamic Functional Connectivity (DFC) studies have lately been found useful in unearthing meaningful, time-varying functional connectivity information in both resting-state and task-based experimental settings. In this study, we examine DFC in the fMRI obtained from two groups of participants, 18 musicians and 18 non-musicians, while they listened to a musical stimulus in a naturalistic setting. We utilize spatial Group Independent Component Analysis (ICA), sliding time window correlations, and a deterministic agglomerative clustering of windowed correlation matrices to identify quasi-stable Functional Connectivity (FC) states in the two groups. To compute cluster centroids that represent FC states, we device and present a method that primarily utilizes windowed correlation matrices occurring repeatedly over time and across participants, while excluding matrices corresponding to spontaneous fluctuations. Preliminary analysis indicate states with greater visuo-sensorimotor integration in musicians, larger presence of DMN states in non-musicians, and variability in states found in musicians due to differences in training and prior experiences.

Abstract

The brain is the most complex biological system that exists. Timbre, in its very nature, is a multidimensional concept with several levels of abstraction thus rendering the investigation of its processing in the brain extremely challenging. Timbre processing can be discussed in relation to levels of abstraction. Low- to midlevel representations can be associated with the neural representation of acoustic structure while high-level abstractions correspond to the neural representation of sound source properties. Furthermore, neural correlates of timbre can be broadly classified based on three stimulus categories, that is, those pertaining to music, speech, and environmental sounds. This chapter summarizes studies that have attempted to uncover neural correlates of varying levels of timbre abstractions. Finally, developments in methodological approaches are described, including the shift from univariate to multivariate statistical models, the employment of more naturalistic stimuli, and brain measurement paradigms from hitherto controlled auditory paradigms.

Abstract

Owing to the stigmatization of mental illnesses such as depression in India [1], there is a need for indirect unsuspecting ways to identify risk for depression and provide timely intervention. Healthy-Unhealthy Music scale (HUMS) [2] is one such assessment tool developed on Australian population that uses music engagement as an indicator of anxiety levels and potential high-risk for depression as assessed by Kessler’s Psychological Distress Scale (K10). The current study aims to ascertain its validity in an Indian setting followed by applying machine learning approaches to predict mental well-being from music associations. A diverse group comprising Indian adult population was assessed using HUMS and mental well-being and proneness to depression measures. HUMS structure investigated via Exploratory factor analyses, and concurrent validity tested with correlations to depression risk and wellbeing revealed high external validity and applicability of HUMS in Indian adult population.Furthermore, very low in-sample error for models like Support Vector Machines (SVM) with nonlinear kernels suggests an underlying pattern between HUMS responses and K10 score. Finally, a two-class model resulted in out of sample accuracy of 81%. To conclude, HUMS demonstrates high generalizability and hence applicability in Indian adult population and potential for employing ML models to capture the underlying pattern.

Abstract

Musical training causes structural and functional changes in the brain due to its sensory-motor demands, but the modulatory effect of musical training on music feature processing in the brain in a continuous music listening paradigm, has not been investigated thus far. In this work, we investigate the differences between musicians and non-musicians in the encoding of musical features encompassing musical timbre, rhythm and tone. 18 musicians and 18 non-musicians were scanned using fMRI while listening to 3 varied stimuli. Acoustic features corresponding to timbre, rhythm and tone were computationally extracted from the stimuli and correlated with brain responses, followed by t-tests on group level maps to uncover encoding differences between the two groups. The musicians demonstrated greater involvement of limbic and reward regions, and regions possessing adaptations to music processing due to training, indicating greater analytic processing. However, as a group, they did not exhibit large regions of consistent correlation patterns, especially in processing high-level features, due to differences in processing strategies arising out of their varied training. The non-musicians exhibited broader regions of correlations, implying greater similarities in bottom-up sensory processing.

Abstract

Keeping time is fundamental for our everyday existence. Various isochronous activities, such as locomotion, require us to use internal timekeeping. This phenomenon comes into play also in other human pursuits such as dance and music. When listening to music, we spontaneously perceive and predict its beat. The process of beat perception comprises both beat inference and beat maintenance, their relative importance depending on the salience of beat in the music. To study functional connectivity associated with these processes in a naturalistic situation, we used functional magnetic resonance imaging to measure brain responses of participants while they were listening to a piece of music containing strong contrasts in beat salience. Subsequently, we utilized dynamic graph analysis and psychophysiological interactions (PPI) analysis in connection with computational modelling of beat salience to investigate how functional connectivity manifests these processes. As the main effect, correlation analyses between the obtained dynamic graph measures and the beat salience measure revealed increased centrality in auditory-motor cortices, cerebellum, and extrastriate visual areas during low beat salience, whereas regions of the default mode- and central executive networks displayed high centrality during high beat salience. PPI analyses revealed partial dissociation of functional networks belonging to this pathway indicating complementary neural mechanisms crucial in beat inference and maintenance, processes pivotal for extracting and predicting temporal regularities in our environment.

Abstract

Encoding models can reveal and decode neural representations in the visual and semantic domains. However, a thorough understanding of how distributed information in auditory cortices and temporal evolution of music contribute to model performance is still lacking in the musical domain. We measured fMRI responses during naturalistic music listening and constructed a two-stage approach that frst mapped musical features in auditory cortices and then decoded novel musical pieces. We then probed the infuence of stimuli duration (number of time points) and spatial extent (number of voxels) on decoding accuracy. Our approach revealed a linear increase in accuracy with duration and a point of optimal model performance for the spatial extent. We further showed that Shannon entropy is a driving factor, boosting accuracy up to 95% for music with highest information content. These fndings provide key insights for future decoding and reconstruction algorithms and open new venues for possible clinical applications.

Abstract

There has been growing interest towards naturalistic neuroimaging experiments, which deepen our understanding of how human brain processes and integrates incoming streams of multifaceted sensory information, as commonly occurs in real world. Music is a good example of such complex continuous phenomenon. In a few recent fMRI studies examining neural correlates of music in continuous listening settings, multiple perceptual attributes of music stimulus were represented by a set of high-level features, produced as the linear combination of the acoustic descriptors computationally extracted from the stimulus audio. New method: fMRI data from naturalistic music listening experiment were employed here. Kernel principal component analysis (KPCA) was applied to acoustic descriptors extracted from the stimulus audio to generate a set of nonlinear stimulus features. Subsequently, perceptual and neural correlates of the generated high-level features were examined.