Modulation of Functional Connectivity in Auditory-Motor Networks in Musicians Compared with Nonmusicians

Resting-state functional connectivity in an auditory network differs between aspiring professional and amateur musicians and correlates with performance

Auditory experience-dependent plasticity is often studied in the domain of musical expertise. Available evidence suggests that years of musical practice are associated with structural and functional changes in auditory cortex and related brain regions. Resting-state functional magnetic resonance imaging (MRI) can be used to investigate neural correlates of musical training and expertise beyond specific task influences. Here, we compared two groups of musicians with varying expertise: 24 aspiring professional musicians preparing for their entrance exam at Universities of Arts versus 17 amateur musicians without any such aspirations but who also performed music on a regular basis. We used an interval recognition task to define task-relevant brain regions and computed functional connectivity and graph-theoretical measures in this network on separately acquired resting-state data. Aspiring professionals performed significantly better on all behavioral indicators including interval recognition and also showed significantly greater network strength and global efficiency than amateur musicians. Critically, both average network strength and global efficiency were correlated with interval recognition task performance assessed in the scanner, and with an additional measure of interval identification ability. These findings demonstrate that task-informed resting-state fMRI can capture connectivity differences that correspond to expertise-related differences in behavior.

Brain-to-brain communication during musical improvisation: a performance case study

Understanding and predicting others' actions in ecological settings is an important research goal in social neuroscience. Here, we deployed a mobile brain-body imaging (MoBI) methodology to analyze inter-brain communication between professional musicians during a live jazz performance. Specifically, bispectral analysis was conducted to assess the synchronization of scalp electroencephalographic (EEG) signals from three expert musicians during a three-part 45 minute jazz performance, during which a new musician joined every five minutes. The bispectrum was estimated for all musician dyads, electrode combinations, and five frequency bands. The results showed higher bispectrum in the beta and gamma frequency bands (13-50 Hz) when more musicians performed together, and when they played a musical phrase synchronously. Positive bispectrum amplitude changes were found approximately three seconds prior to the identified synchronized performance events suggesting preparatory cortical activity predictive of concerted behavioral action. Moreover, a higher amount of synchronized EEG activity, across electrode regions, was observed as more musicians performed, with inter-brain synchronization between the temporal, parietal, and occipital regions the most frequent. Increased synchrony between the musicians' brain activity reflects shared multi-sensory processing and movement intention in a musical improvisation task.

Graph Theoretical Network Structures Underlie Age-Related Differences in the Functional Connectome During Rest and Music Listening

Aging is associated with decreased functional connectivity within the default mode network, as well as auditory and reward systems which are involved in music listening. Understanding how music listening affects network organization of the aging brain, both globally and specific to the brain networks, will have implications for designing lifestyle interventions that tap into distinct networks in the brain. Here we apply graph-theory metrics of modularity, global efficiency, clustering coefficients, degrees, and betweenness centrality to compare younger and older adults (YA/OA, N=24 per group) in fMRI connectivity during rest and a music listening task. Results show a less modular but more globally efficient connectome in OAs, especially during music listening, resulting in main effects of group and task, as well as group-by-task interactions. ROI analyses indicated that the posterior cingulate is more centrally located than the medial prefrontal cortex in OAs. Overall, reduced modularity and increased global efficiency with age is in keeping with previously-observed functional reorganizations, and interaction effects show that age-related differences in baseline network organization are reflected in, potentially magnified by, music listening.

Using cortico-cerebellar structural patterns to classify early- and late-trained musicians

A body of current evidence suggests that there is a sensitive period for musical training: people who begin training before the age of seven show better performance on tests of musical skill, and also show differences in brain structure-especially in motor cortical and cerebellar regions-compared with those who start later. We used support vector machine models-a subtype of supervised machine learning-to investigate distributed patterns of structural differences between early-trained (ET) and late-trained (LT) musicians and to better understand the age boundaries of the sensitive period for early musicianship. After selecting regions of interest from the cerebellum and cortical sensorimotor regions, we applied recursive feature elimination with cross-validation to produce a model which optimally and accurately classified ET and LT musicians. This model identified a combination of 17 regions, including 9 cerebellar and 8 sensorimotor regions, and maintained a high accuracy and sensitivity (true positives, i.e., ET musicians) without sacrificing specificity (true negatives, i.e., LT musicians). Critically, this model-which defined ET musicians as those who began their training before the age of 7-outperformed all other models in which age of start was earlier or later (between ages 5-10). Our model's ability to accurately classify ET and LT musicians provides additional evidence that musical training before age 7 affects cortico-cerebellar structure in adulthood, and is consistent with the hypothesis that connected brain regions interact during development to reciprocally influence brain and behavioral maturation.

Musical Experience Relates to Insula-Based Functional Connectivity in Older Adults

Engaging in musical activities throughout the lifespan may protect against age-related cognitive decline and modify structural and functional connectivity in the brain. Prior research suggests that musical experience modulates brain regions that integrate different modalities of sensory information, such as the insula. Most of this research has been performed in individuals classified as professional musicians; however, general musical experiences across the lifespan may also confer beneficial effects on brain health in older adults. The current study investigated whether general musical experience, characterized using the Goldsmith Music Sophistication Index (Gold-MSI), was associated with functional connectivity in older adults (age = 65.7 ± 4.4, n = 69). We tested whether Gold-MSI was associated with individual differences in the functional connectivity of three a priori hypothesis-defined seed regions in the insula (i.e., dorsal anterior, ventral anterior, and posterior insula). We found that older adults with more musical experience showed greater functional connectivity between the dorsal anterior insula and the precentral and postcentral gyrus, and between the ventral anterior insula and diverse brain regions, including the insula and prefrontal cortex, and decreased functional connectivity between the ventral anterior insula and thalamus (voxel p < 0.01, cluster FWE p < 0.05). Follow-up correlation analyses showed that the singing ability subscale score was key in driving the association between functional connectivity differences and musical experience. Overall, our findings suggest that musical experience, even among non-professional musicians, is related to functional brain reorganization in older adults.

Dual-Task-Based Music Therapy to Improve Executive Functioning of Elderly Patients with Early Stage Alzheimer's Disease: A Multiple Case Study

Deficits in executive functioning are a common feature of Alzheimer's disease (AD) and result from impairment in the central executive system. As a result, elderly patients with early stage AD may require interventions that are more cognitively intense than traditional interventions. To address this need, in this multiple case study, we explored a dual-task-based music therapy intervention that involved drum playing and singing designed to induce attentional and motor controls. Three octogenarians diagnosed with early stage AD participated in 12 dual-task-based music therapy sessions over 6 weeks. Measures of executive functioning and the performance of a bimanual drum tapping task were evaluated before and after the intervention. Improvements in executive functioning were observed for participants A and C. After the intervention, reduced mean synchronization errors were found for the simultaneous tapping condition for all three participants. Although there was variability in the functional changes between participants, it is noteworthy that positive improvements in the elderly patients with early stage AD were obtained following dual-task-based music therapy. The results suggest that music therapy integrated into the dual-task paradigm can be an effective way to address degenerative cognitive deficits among elderly patients with early stage AD.

Music in the brain

Music is ubiquitous across human cultures - as a source of affective and pleasurable experience, moving us both physically and emotionally - and learning to play music shapes both brain structure and brain function. Music processing in the brain - namely, the perception of melody, harmony and rhythm - has traditionally been studied as an auditory phenomenon using passive listening paradigms. However, when listening to music, we actively generate predictions about what is likely to happen next. This enactive aspect has led to a more comprehensive understanding of music processing involving brain structures implicated in action, emotion and learning. Here we review the cognitive neuroscience literature of music perception. We show that music perception, action, emotion and learning all rest on the human brain's fundamental capacity for prediction - as formulated by the predictive coding of music model. This Review elucidates how this formulation of music perception and expertise in individuals can be extended to account for the dynamics and underlying brain mechanisms of collective music making. This in turn has important implications for human creativity as evinced by music improvisation. These recent advances shed new light on what makes music meaningful from a neuroscientific perspective.

Musicianship-Related Structural and Functional Cortical Features Are Preserved in Elderly Musicians

Background

Professional musicians are a model population for exploring basic auditory function, sensorimotor and multisensory integration, and training-induced neuroplasticity. The brain of musicians exhibits distinct structural and functional cortical features; however, little is known about how these features evolve during aging. This multiparametric study aimed to examine the functional and structural neural correlates of lifelong musical practice in elderly professional musicians.

Methods

Sixteen young musicians, 16 elderly musicians (age >70), and 15 elderly non-musicians participated in the study. We assessed gray matter metrics at the whole-brain and region of interest (ROI) levels using high-resolution magnetic resonance imaging (MRI) with the Freesurfer automatic segmentation and reconstruction pipeline. We used BrainVoyager semiautomated segmentation to explore individual auditory cortex morphotypes. Furthermore, we evaluated functional blood oxygenation level-dependent (BOLD) activations in auditory and non-auditory regions by functional MRI (fMRI) with an attentive tone-listening task. Finally, we performed discriminant function analyses based on structural and functional ROIs.

Results

A general reduction of gray matter metrics distinguished the elderly from the young subjects at the whole-brain level, corresponding to widespread natural brain atrophy. Age- and musicianship-dependent structural correlations revealed group-specific differences in several clusters including superior, middle, and inferior frontal as well as perirolandic areas. In addition, the elderly musicians exhibited increased gyrification of auditory cortex like the young musicians. During fMRI, the elderly non-musicians activated predominantly auditory regions, whereas the elderly musicians co-activated a much broader network of auditory association areas, primary and secondary motor areas, and prefrontal and parietal regions like, albeit weaker, the young musicians. Also, group-specific age- and musicianship-dependent functional correlations were observed in the frontal and parietal regions. Moreover, discriminant function analysis could separate groups with high accuracy based on a set of specific structural and functional, mainly temporal and occipital, ROIs.

Conclusion

In conclusion, despite naturally occurring senescence, the elderly musicians maintained musicianship-specific structural and functional cortical features. The identified structural and functional brain regions, discriminating elderly musicians from non-musicians, might be of relevance for the aging musicians’ brain. To what extent lifelong musical activity may have a neuroprotective impact needs to be addressed further in larger longitudinal studies.

Neural Plasticity in a French Horn Player with Bilateral Amelia

Precise control of movement and timing play a key role in musical performance. This motor skill requires coordination across multiple joints, muscles, and limbs, which is acquired through extensive musical training from childhood on. Thus, making music can be a strong driver for neuroplasticity. We here present the rare case of a professional french horn player with a congenital bilateral amelia of the upper limbs. We were able to show a unique cerebral and cerebellar somatotopic representation of his toe and feet, that do not follow the characteristic patterns of contralateral cortical and ipsilateral cerebellar layout. Although being a professional horn player who trained his embouchure muscles, including tongue, pharyngeal, and facial muscle usage excessively, there were no obvious signs for an expanded somatosensory representation in this part of the classic homunculus. Compared to the literature and in contrast to control subjects, the musicians' foot movement-related activations occurred in cerebellar areas that are typically more related to hand than to foot activation.

Sex Differences are Reflected in Microstructural White Matter Alterations of Musical Sophistication: A Diffusion MRI Study

Background: The human-specified ability to engage with different kinds of music in sophisticated ways is named “Musical Sophistication.” Herein, we investigated specific white matter (WM) tracts that are associated with musical sophistication and musicality in both genders, separately, using Diffusion MRI connectometry approach. We specifically aimed to explore potential sex differences regarding WM alterations correlated with musical sophistication.

Methods: 123 healthy participants [70 (56.9%) were male, mean age = 36.80 ± 18.86 year], who were evaluated for musical sophistication using Goldsmiths Musical Sophistication Index (Gold-MSI) self-assessment instrument from the LEMON database, were recruited in this study. The WM correlates of two Gold-MSI subscales (active engagement and music training) were analyzed. Images were prepared and analyzed with diffusion connectometry to construct the local connectome. Multiple regression models were then fitted to address the correlation of local connectomes with Gold-MSI components with the covariates of age and handedness.

Results: a significant positive correlation between WM integrity in the corpus callosum (CC), right corticospinal tract (CST), cingulum, middle cerebellar peduncle (MCP), bilateral parieto-pontine tract, bilateral cerebellum, and left arcuate fasciculus (AF) and both active engagement [false discovery rate (FDR) = 0.008] and music training (FDR = 0.057) was detected in males. However, WM integrity in the body of CC, MCP, and cerebellum in females showed an inverse association with active engagement (FDR = 0.046) and music training (FDR = 0.032).

Conclusion: WM microstructures with functional connection with motor and somatosensory areas (CST, cortico-pontine tracts, CC, cerebellum, cingulum, and MCP) and language processing area (AF) have significant correlation with music engagement and training. Our findings show that these associations are different between males and females, which could potentially account for distinctive mechanisms related to musical perception and musical abilities across genders.

The prevalence of the Val66Met polymorphism in musicians: Possible evidence for compensatory neuroplasticity from a pilot study

The study compared the prevalence of the Val66Met Brain-derived Neurotrophic Factor single nucleotide polymorphism (rs6265) in a sample of musicians (N = 50) to an ethnically matched general population sample from the 1000 Human Genome Project (N = 424). Met-carriers of the polymorphism (Val/Met and Met/Met genotypes) are typically present in 25–30% of the general population and have associated deficits in motor learning and plasticity. Many studies have assessed the benefits of long-term music training for neuroplasticity and motor learning. This study takes a unique genetic approach investigating if the prevalence of the Val66Met BDNF polymorphism, which negatively affects motor learning, is significantly different in musicians from the general population. Our genotype and allele frequency analyses revealed that the distribution of the Val66Met polymorphism was not significantly different in musicians versus the general population (p = 0.6447 for genotype analysis and p = 0.8513 allele analysis). In the Musician sample (N = 50), the prevalence of the Val/Met genotype was 40% and the prevalence of the Met/Met genotype was 2%. In the 1000 Human Genome Project subset (N = 424), the prevalence of Val/Met was 33.25% and the Met/Met genotype prevalence was 4%. Therefore, musicians do exist with the Val66Met polymorphism and the characteristics of long-term music training may compensate for genetic predisposition to motor learning deficits. Since the polymorphism has significant implications for stroke rehabilitation, future studies may consider the implications of the polymorphism in music-based interventions such as Neurologic Music Therapy.

The impact of early musical training on striatal functional connectivity

Evidence from language, visual and sensorimotor learning suggests that training early in life is more effective. The present work explores the hypothesis that learning during sensitive periods involves distinct brain networks in addition to those involved when learning later in life. Expert pianists were tested who started their musical training early (<7 years of age; n = 21) or late (n = 15), but were matched for total lifetime practice. Motor timing expertise was assessed using a musical scale playing task. Brain activity at rest was measured using fMRI and compared with a control group of nonmusicians (n = 17). Functional connectivity from seeds in the striatum revealed a striatal-cortical-sensorimotor network that was observed only in the early-onset group. In this network, higher connectivity correlated with greater motor timing expertise, which resulted from early/late group differences in motor timing expertise. By contrast, networks that differentiated musicians and nonmusicians, namely a striatal-occipital-frontal-cerebellar network in which connectivity was higher in musicians, tended to not show differences between early and late musicians and not be correlated with motor timing expertise. These results parcel musical sensorimotor neuroplasticity into a set of musicianship-related networks and a distinct set of predominantly early-onset networks. The findings lend support to the possibility that we can learn skills more easily early in development because during sensitive periods we recruit distinct brain networks that are no longer implicated in learning later in life.

The Microstructural Plasticity of the Arcuate Fasciculus Undergirds Improved Speech in Noise Perception in Musicians

Musical training is thought to be related to improved language skills, for example, understanding speech in background noise. Although studies have found that musicians and nonmusicians differed in morphology of bilateral arcuate fasciculus (AF), none has associated such white matter features with speech-in-noise (SIN) perception. Here, we tested both SIN and the diffusivity of bilateral AF segments in musicians and nonmusicians using diffusion tensor imaging. Compared with nonmusicians, musicians had higher fractional anisotropy (FA) in the right direct AF and lower radial diffusivity in the left anterior AF, which correlated with SIN performance. The FA-based laterality index showed stronger right lateralization of the direct AF and stronger left lateralization of the posterior AF in musicians than nonmusicians, with the posterior AF laterality predicting SIN accuracy. Furthermore, hemodynamic activity in right superior temporal gyrus obtained during a SIN task played a full mediation role in explaining the contribution of the right direct AF diffusivity on SIN performance, which therefore links training-related white matter plasticity, brain hemodynamics, and speech perception ability. Our findings provide direct evidence that differential microstructural plasticity of bilateral AF segments may serve as a neural foundation of the cross-domain transfer effect of musical experience to speech perception amid competing noise.

MEG Intersubject Phase Locking of Stimulus-Driven Activity during Naturalistic Speech Listening Correlates with Musical Training

Musical training is associated with increased structural and functional connectivity between auditory sensory areas and higher-order brain networks involved in speech and motor processing. Whether such changed connectivity patterns facilitate the cortical propagation of speech information in musicians remains poorly understood. We here used magnetoencephalography (MEG) source imaging and a novel seed-based intersubject phase-locking approach to investigate the effects of musical training on the interregional synchronization of stimulus-driven neural responses during listening to naturalistic continuous speech presented in silence. MEG data were obtained from 20 young human subjects (both sexes) with different degrees of musical training. Our data show robust bilateral patterns of stimulus-driven interregional phase synchronization between auditory cortex and frontotemporal brain regions previously associated with speech processing. Stimulus-driven phase locking was maximal in the delta band, but was also observed in the theta and alpha bands. The individual duration of musical training was positively associated with the magnitude of stimulus-driven alpha-band phase locking between auditory cortex and parts of the dorsal and ventral auditory processing streams. These findings provide evidence for a positive relationship between musical training and the propagation of speech-related information between auditory sensory areas and higher-order processing networks, even when speech is presented in silence. We suggest that the increased synchronization of higher-order cortical regions to auditory cortex may contribute to the previously described musician advantage in processing speech in background noise.SIGNIFICANCE STATEMENT Musical training has been associated with widespread structural and functional brain plasticity. It has been suggested that these changes benefit the production and perception of music but can also translate to other domains of auditory processing, such as speech. We developed a new magnetoencephalography intersubject analysis approach to study the cortical synchronization of stimulus-driven neural responses during the perception of continuous natural speech and its relationship to individual musical training. Our results provide evidence that musical training is associated with higher synchronization of stimulus-driven activity between brain regions involved in early auditory sensory and higher-order processing. We suggest that the increased synchronized propagation of speech information may contribute to the previously described musician advantage in processing speech in background noise.

Musical Expertise Shapes Functional and Structural Brain Networks Independent of Absolute Pitch Ability

Professional musicians are a popular model for investigating experience-dependent plasticity in human large-scale brain networks. A minority of musicians possess absolute pitch, the ability to name a tone without reference. The study of absolute pitch musicians provides insights into how a very specific talent is reflected in brain networks. Previous studies of the effects of musicianship and absolute pitch on large-scale brain networks have yielded highly heterogeneous findings regarding the localization and direction of the effects. This heterogeneity was likely influenced by small samples and vastly different methodological approaches. Here, we conducted a comprehensive multimodal assessment of effects of musicianship and absolute pitch on intrinsic functional and structural connectivity using a variety of commonly used and state-of-the-art multivariate methods in the largest sample to date (n = 153 female and male human participants; 52 absolute pitch musicians, 51 non-absolute pitch musicians, and 50 non-musicians). Our results show robust effects of musicianship in interhemispheric and intrahemispheric connectivity in both structural and functional networks. Crucially, most of the effects were replicable in both musicians with and without absolute pitch compared with non-musicians. However, we did not find evidence for an effect of absolute pitch on intrinsic functional or structural connectivity in our data: The two musician groups showed strikingly similar networks across all analyses. Our results suggest that long-term musical training is associated with robust changes in large-scale brain networks. The effects of absolute pitch on neural networks might be subtle, requiring very large samples or task-based experiments to be detected.SIGNIFICANCE STATEMENT A question that has fascinated neuroscientists, psychologists, and musicologists for a long time is how musicianship and absolute pitch, the rare talent to name a tone without reference, are reflected in large-scale networks of the human brain. Much is still unknown as previous studies have reported widely inconsistent results based on small samples. Here, we investigate the largest sample of musicians and non-musicians to date (n = 153) using a multitude of established and novel analysis methods. Results provide evidence for robust effects of musicianship on functional and structural networks that were replicable in two separate groups of musicians and independent of absolute pitch ability.

Observing Plasticity of the Auditory System: Volumetric Decreases Along with Increased Functional Connectivity in Aspiring Professional Musicians

Playing music relies on several sensory systems and the motor system, and poses strong demands on control processes, hence, offering an excellent model to study how experience can mold brain structure and function. Although most studies on neural correlates of music expertise rely on cross-sectional comparisons, here we compared within-person changes over time in aspiring professionals intensely preparing for an entrance exam at a University of the Arts to skilled amateur musicians not preparing for a music exam. In the group of aspiring professionals, we observed gray-matter volume decrements in left planum polare, posterior insula, and left inferior frontal orbital gyrus over a period of about 6 months that were absent among the amateur musicians. At the same time, the left planum polare, the largest cluster of structural change, showed increasing functional connectivity with left and right auditory cortex, left precentral gyrus, left supplementary motor cortex, left and right postcentral gyrus, and left cingulate cortex, all regions previously identified to relate to music expertise. In line with the expansion-renormalization pattern of brain plasticity (Wenger et al., 2017a. Expansion and renormalization of human brain structure during skill acquisition. Trends Cogn Sci. 21:930-939.), the aspiring professionals might have been in the selection and refinement period of plastic change.

Modifications in the Topological Structure of EEG Functional Connectivity Networks during Listening Tonal and Atonal Concert Music in Musicians and Non-Musicians

The present work aims to demonstrate the hypothesis that atonal music modifies the topological structure of electroencephalographic (EEG) connectivity networks in relation to tonal music. To this, EEG monopolar records were taken in musicians and non-musicians while listening to tonal, atonal, and pink noise sound excerpts. EEG functional connectivities (FC) among channels assessed by a phase synchronization index previously thresholded using surrogate data test were computed. Sound effects, on the topological structure of graph-based networks assembled with the EEG-FCs at different frequency-bands, were analyzed throughout graph metric and network-based statistic (NBS). Local and global efficiency normalized (vs. random-network) measurements (NLE|NGE) assessing network information exchanges were able to discriminate both music styles irrespective of groups and frequency-bands. During tonal audition, NLE and NGE values in the beta-band network get close to that of a small-world network, while during atonal and even more during noise its structure moved away from small-world. These effects were attributed to the different timbre characteristics (sounds spectral centroid and entropy) and different musical structure. Results from networks topographic maps for strength and NLE of the nodes, and for FC subnets obtained from the NBS, allowed discriminating the musical styles and verifying the different strength, NLE, and FC of musicians compared to non-musicians.

Putting Cells in Motion: Advantages of Endogenous Boosting of BDNF Production

Motor exercise, such as sport or musical activities, helps with a plethora of diseases by modulating brain functions in neocortical and subcortical regions, resulting in behavioural changes related to mood regulation, well-being, memory, and even cognitive preservation in aging and neurodegenerative diseases. Although evidence is accumulating on the systemic neural mechanisms mediating these brain effects, the specific mechanisms by which exercise acts upon the cellular level are still under investigation. This is particularly the case for music training, a much less studied instance of motor exercise than sport. With regards to sport, consistent neurobiological research has focused on the brain-derived neurotrophic factor (BDNF), an essential player in the central nervous system. BDNF stimulates the growth and differentiation of neurons and synapses. It thrives in the hippocampus, the cortex, and the basal forebrain, which are the areas vital for memory, learning, and higher cognitive functions. Animal models and neurocognitive experiments on human athletes converge in demonstrating that physical exercise reliably boosts BDNF levels. In this review, we highlight comparable early findings obtained with animal models and elderly humans exposed to musical stimulation, showing how perceptual exposure to music might affect BDNF release, similar to what has been observed for sport. We subsequently propose a novel hypothesis that relates the neuroplastic changes in the human brains after musical training to genetically- and exercise-driven BDNF levels.

Transcranial direct current stimulation modulates brain functional connectivity in autism

Autism spectrum disorder (ASD) is characterized by deficits in social interactions, impairments in language and communication, and highly restricted behavioral interests. Transcranial direct current stimulation (tDCS) is a widely used form of noninvasive stimulation and may have therapeutic potential for ASD. So far, despite the widespread use of this technique in the neuroscience field, its effects on network-level neural activity and the underlying mechanisms of any effects are still unclear. In the present study, we used electroencephalography (EEG) to investigate tDCS induced brain network changes in children with ASD before and after active and sham stimulation. We recorded 5 min of resting state EEG before and after a single session of tDCS (of approximately 20 min) over dorsolateral prefrontal cortex (DLPFC). Two network-based methods were applied to investigate tDCS modulation on brain networks: 1) temporal network dynamics were analyzed by comparing "flexibility" changes before vs after stimulation, and 2) frequency specific network changes were identified using non-negative matrix factorization (NMF). We found 1) an increase in network flexibility following tDCS (rapid network configuration of dynamic network communities), 2) specific increase in interhemispheric connectivity within the alpha frequency band following tDCS. Together, these results demonstrate that tDCS could help modify both local and global brain network dynamics, and highlight stimulation-induced differences in the manifestation of network reconfiguration. Meanwhile, frequency-specific subnetworks, as a way to index local and global information processing, highlight the core modulatory effects of tDCS on the modular architecture of the functional connectivity patterns within higher frequency bands.

Left-handed musicians show a higher probability of atypical cerebral dominance for language

Music processing and right hemispheric language lateralization share a common network in the right auditory cortex and its frontal connections. Given that the development of hemispheric language dominance takes place over several years, this study tested whether musicianship could increase the probability of observing right language dominance in left-handers. Using a classic fMRI language paradigm, results showed that atypical lateralization was more predominant in musicians (40%) than in nonmusicians (5%). Comparison of left-handers with typical left and atypical right lateralization revealed that: (a) atypical cases presented a thicker right pars triangularis and more gyrified left Heschl's gyrus; and (b) the right pars triangularis of atypical cases showed a stronger intra-hemispheric functional connectivity with the right angular gyrus, but a weaker interhemispheric functional connectivity with part of the left Broca's area. Thus, musicianship is the first known factor related to a higher prevalence of atypical language dominance in healthy left-handed individuals. We suggest that differences in the frontal and temporal cortex might act as shared predisposing factors to both musicianship and atypical language lateralization.

Beatboxers and Guitarists Engage Sensorimotor Regions Selectively When Listening to the Instruments They can Play

Studies of classical musicians have demonstrated that expertise modulates neural responses during auditory perception. However, it remains unclear whether such expertise-dependent plasticity is modulated by the instrument that a musician plays. To examine whether the recruitment of sensorimotor regions during music perception is modulated by instrument-specific experience, we studied nonclassical musicians-beatboxers, who predominantly use their vocal apparatus to produce sound, and guitarists, who use their hands. We contrast fMRI activity in 20 beatboxers, 20 guitarists, and 20 nonmusicians as they listen to novel beatboxing and guitar pieces. All musicians show enhanced activity in sensorimotor regions (IFG, IPC, and SMA), but only when listening to the musical instrument they can play. Using independent component analysis, we find expertise-selective enhancement in sensorimotor networks, which are distinct from changes in attentional networks. These findings suggest that long-term sensorimotor experience facilitates access to the posterodorsal "how" pathway during auditory processing.

The Effects of Bimanual Coordination in Music Interventions on Executive Functions in Aging Adults

Music training programs have been shown to enhance executive functions in aging adults; however, little is known regarding the extent to which different types of bimanual coordination (i.e., fine and gross motor) in music instruction contribute to these outcomes. The aim of this study was to examine the effects of bimanual coordination in music interventions on cognitive performance in healthy older adults (60-80 years). Participants (N = 135) completed motor measures and battery of standardized cognitive measures, before and after a 16-week music training program with a 3 h practice requirement. All participants were matched by age, education, and estimate of intelligence to one of three training programs: piano training (fine motor); percussion instruction (gross motor), and music listening instruction (MLI) (no motor control condition). Results of a Repeated Measures ANOVA revealed significant enhancements in bimanual synchronization and visual scanning/working memory abilities for fine and gross motor training groups as compared to MLI. Pairwise comparisons revealed that piano training significantly improved motor synchronization skills as compared to percussion instruction or music listening. Results suggest that active music performance may benefit working memory, the extent of these benefits may depend upon coordination demands.

Different role of the supplementary motor area and the insula between musicians and non-musicians in a controlled musical creativity task

The ability to compose creative musical ideas depends on the cooperation of brain mechanisms involved in multiple processes, including controlled creative cognition, which is a type of creativity that has so far been poorly researched. Therefore, the objective of this study was to examine the brain evoked activations by using fMRI, in both musicians and non-musicians, during a general task of controlled musical creativity and its relationship with general creativity. Results revealed that during a rhythmic improvisation task, musicians show greater activation of the motor supplementary area, the anterior cingulate cortex, the dorsolateral prefrontal cortex, and the insula, along with greater deactivation of the default mode network in comparison with non-musicians. For the group of musicians, we also found a positive correlation between the time improvising and the activation of the supplementary motor area, whilst in the non-musicians group improvisation time correlated with the activation of the insula. The results found for the musicians support the notion that the supplementary motor area plays a role in the representation and execution of musical behaviour, while the results in non-musicians reveal the role of the insula in the processing of novel musical information.

Alteration of perceived emotion and brain functional connectivity by changing the musical rhythmic pattern

The arrangement of musical notes and their time intervals, also known as musical rhythm is one of the core elements of music. Nevertheless, the cognitive process and neural mechanism of the human brain that underlay the perception of musical rhythm are poorly understood. In this study, we hypothesized that changes in musical rhythmic patterns alter the emotional content expressed by music and the way it is perceived, that assumably causes specific changes in the brain functional connectome. Therefore, 18 male children aged 10-14 years old were recruited and exposed to 12 musical excerpts while their brain's electrical activity was recorded using a 32-channel EEG recorder. The musical rhythmic patterns were changed by manipulating only note values in beats while keeping time signature and other elements in a fixed state. The experienced emotions were assessed using a 2-dimensional self-assessment manikin questionnaire. The behavioral data showed that an increase in the complexity of musical rhythmic patterns significantly enhances perceived valence and arousal levels. In addition, the pattern of brain functional connectivity was also estimated using the weighted phase lag index and their association with behavioral changes was calculated. Interestingly, the behavioral changes were mainly associated with alteration of brain functional connectivity at the alpha band in the fronto-central connections. These results emphasize the important role of the motor cortical site-fronto-central connections, in the perception of musical rhythmic pattern. These findings may improve conception of the underlying brain mechanism involved in the perception of musical rhythm.

Music in premature infants enhances high-level cognitive brain networks

Preterm babies are cared for in neonatal intensive care units (NICU), which are busy places with a lot of mechanical noise increasingly recognized to disrupt normal brain development. NICUs therefore invest in developmental care procedures, with music for example, but neurobiological evidence for these interventions is missing. We present results from a clinical trial to study the effects of a music intervention on preterm infants’ brain development. Based on resting-state fMRI, we provide evidence that music enhanced connectivity in a brain circuitry involving the salience network with regions implicated in sensory and higher-order cognitive functions, previously found to be altered in preterm infants. To our knowledge, this study is unique in observing an impact of music on brain development in preterm newborns.

Neonatal intensive care units are willing to apply environmental enrichment via music for preterm newborns. However, no evidence of an effect of music on preterm brain development has been reported to date. Using resting-state fMRI, we characterized a circuitry of interest consisting of three network modules interconnected by the salience network that displays reduced network coupling in preterm compared with full-term newborns. Interestingly, preterm infants exposed to music in the neonatal intensive care units have significantly increased coupling between brain networks previously shown to be decreased in premature infants: the salience network with the superior frontal, auditory, and sensorimotor networks, and the salience network with the thalamus and precuneus networks. Therefore, music exposure leads to functional brain architectures that are more similar to those of full-term newborns, providing evidence for a beneficial effect of music on the preterm brain.

Increased Insular Connectivity and Enhanced Empathic Ability Associated with Dance/Music Training

Dance and music are expressive art forms. Previous behavioural studies have reported that dancers/musicians show a better sensorimotor ability and emotional representation of others. However, the neural mechanism behind this phenomenon is not completely understood. Recently, intensive researches have identified that the insula is highly enrolled in the empathic process. Thus, to expand the knowledge of insular function associated with empathy under the dance/music training background, we mapped the insular network and its associated brain regions in 21 dancers, 20 musicians, and 24 healthy controls using resting-state functional connectivity (FC) analysis. Whole brain voxel-based analysis was performed using seeds from the posterior insula (PI), the ventral anterior insula (vAI), and the dorsal anterior insula (dAI). The training effects of dance and music on insular subnetworks were then evaluated using one-way analysis of variance ANOVA. Increased insular FC with those seeds was found in dancers/musicians, including PI and anterior cingulated cortex (ACC), vAI and middle temporal gyrus (MTG) and middle cingulated cortex (MCC), and dAI and ACC and MTG. In addition, significant associations were found between discrepant insular FC patterns and empathy scores in dancers and musicians. These results indicated that dance/music training might enhance insular subnetwork function, which would facilitate integration of intero/exteroceptive information and result in better affective sensitivity. Those changes might finally facilitate the subjects' empathic ability.

Structural Covariance Analysis Reveals Differences Between Dancers and Untrained Controls

Dancers and musicians differ in brain structure from untrained individuals. Structural covariance (SC) analysis can provide further insight into training-associated brain plasticity by evaluating interregional relationships in gray matter (GM) structure. The objectives of the present study were to compare SC of cortical thickness (CT) between expert dancers, expert musicians and untrained controls, as well as to examine the relationship between SC and performance on dance- and music-related tasks. A reduced correlation between CT in the left dorsolateral prefrontal cortex (DLPFC) and mean CT across the whole brain was found in the dancers compared to the controls, and a reduced correlation between these two CT measures was associated with higher performance on a dance video game task. This suggests that the left DLPFC is structurally decoupled in dancers and may be more strongly affected by local training-related factors than global factors in this group. This work provides a better understanding of structural brain connectivity and training-induced brain plasticity, as well as their interaction with behavior in dance and music.

Insights Into Auditory Cortex Dynamics From Non-invasive Brain Stimulation

Non-invasive brain stimulation (NIBS) has been widely used as a research tool to modulate cortical excitability of motor as well as non-motor areas, including auditory or language-related areas. NIBS, especially transcranial magnetic stimulation (TMS) and transcranial direct current stimulation, have also been used in clinical settings, with however variable therapeutic outcome, highlighting the need to better understand the mechanisms underlying NIBS techniques. TMS was initially used to address causality between specific brain areas and related behavior, such as language production, providing non-invasive alternatives to lesion studies. Recent literature however suggests that the relationship is not as straightforward as originally thought, and that TMS can show both linear and non-linear modulation of brain responses, highlighting complex network dynamics. In particular, in the last decade, NIBS studies have enabled further advances in our understanding of auditory processing and its underlying functional organization. For instance, NIBS studies showed that even when only one auditory cortex is stimulated unilaterally, bilateral modulation may result, thereby highlighting the influence of functional connectivity between auditory cortices. Additional neuromodulation techniques such as transcranial alternating current stimulation or transcranial random noise stimulation have been used to target frequency-specific neural oscillations of the auditory cortex, thereby providing further insight into modulation of auditory functions. All these NIBS techniques offer different perspectives into the function and organization of auditory cortex. However, further research should be carried out to assess the mode of action and long-term effects of NIBS to optimize their use in clinical settings.

Musical training induces functional and structural auditory-motor network plasticity in young adults

Playing music requires a strong coupling of perception and action mediated by multimodal integration of brain regions, which can be described as network connections measured by anatomical and functional correlations between regions. However, the structural and functional connectivities within and between the auditory and sensorimotor networks after long-term musical training remain largely uninvestigated. Here, we compared the structural connectivity (SC) and resting-state functional connectivity (rs-FC) within and between the two networks in 29 novice healthy young adults before and after musical training (piano) with those of another 27 novice participants who were evaluated longitudinally but with no intervention. In addition, a correlation analysis was performed between the changes in FC or SC with practice time in the training group. As expected, participants in the training group showed increased FC within the sensorimotor network and increased FC and SC of the auditory-motor network after musical training. Interestingly, we further found that the changes in FC within the sensorimotor network and SC of the auditory-motor network were positively correlated with practice time. Our results indicate that musical training could induce enhanced local interaction and global integration between musical performance-related regions, which provides insights into the mechanism of brain plasticity in young adults.

Functional connectivity corresponding to the tonotopic differentiation of the human auditory cortex

Recent research has demonstrated that resting-state functional connectivity (RS-FC) within the human auditory cortex (HAC) is frequency-selective, but whether RS-FC between the HAC and other brain areas is differentiated by frequency remains unclear. Three types of data were collected in this study, including resting-state functional magnetic resonance imaging (fMRI) data, task-based fMRI data using six pure tone stimuli (200, 400, 800, 1,600, 3,200, and 6,400 Hz), and structural imaging data. We first used task-based fMRI to identify frequency-selective cortical regions in the HAC. Six regions of interest (ROIs) were defined based on the responses of 50 participants to the six pure tone stimuli. Then, these ROIs were used as seeds to determine RS-FC between the HAC and other brain regions. The results showed that there was RS-FC between the HAC and brain regions that included the superior temporal gyrus, dorsolateral prefrontal cortex (DL-PFC), parietal cortex, occipital lobe, and subcortical structures. Importantly, significant differences in FC were observed among most of the brain regions that showed RS-FC with the HAC. Specifically, there was stronger RS-FC between (1) low-frequency (200 and 400 Hz) regions and brain regions including the premotor cortex, somatosensory/-association cortex, and DL-PFC; (2) intermediate-frequency (800 and 1,600 Hz) regions and brain regions including the anterior/posterior superior temporal sulcus, supramarginal gyrus, and inferior frontal cortex; (3) intermediate/low-frequency regions and vision-related regions; (4) high-frequency (3,200 and 6,400 Hz) regions and the anterior cingulate cortex or left DL-PFC. These findings demonstrate that RS-FC between the HAC and other brain areas is frequency selective.

Decoding Musical Training from Dynamic Processing of Musical Features in the Brain

Pattern recognition on neural activations from naturalistic music listening has been successful at predicting neural responses of listeners from musical features, and vice versa. Inter-subject differences in the decoding accuracies have arisen partly from musical training that has widely recognized structural and functional effects on the brain. We propose and evaluate a decoding approach aimed at predicting the musicianship class of an individual listener from dynamic neural processing of musical features. Whole brain functional magnetic resonance imaging (fMRI) data was acquired from musicians and nonmusicians during listening of three musical pieces from different genres. Six musical features, representing low-level (timbre) and high-level (rhythm and tonality) aspects of music perception, were computed from the acoustic signals, and classification into musicians and nonmusicians was performed on the musical feature and parcellated fMRI time series. Cross-validated classification accuracy reached 77% with nine regions, comprising frontal and temporal cortical regions, caudate nucleus, and cingulate gyrus. The processing of high-level musical features at right superior temporal gyrus was most influenced by listeners’ musical training. The study demonstrates the feasibility to decode musicianship from how individual brains listen to music, attaining accuracy comparable to current results from automated clinical diagnosis of neurological and psychological disorders.

Musical training sharpens and bonds ears and tongue to hear speech better

The idea that musical training improves speech perception in challenging listening environments is appealing and of clinical importance, yet the mechanisms of any such musician advantage are not well specified. Here, using functional magnetic resonance imaging (fMRI), we found that musicians outperformed nonmusicians in identifying syllables at varying signal-to-noise ratios (SNRs), which was associated with stronger activation of the left inferior frontal and right auditory regions in musicians compared with nonmusicians. Moreover, musicians showed greater specificity of phoneme representations in bilateral auditory and speech motor regions (e.g., premotor cortex) at higher SNRs and in the left speech motor regions at lower SNRs, as determined by multivoxel pattern analysis. Musical training also enhanced the intrahemispheric and interhemispheric functional connectivity between auditory and speech motor regions. Our findings suggest that improved speech in noise perception in musicians relies on stronger recruitment of, finer phonological representations in, and stronger functional connectivity between auditory and frontal speech motor cortices in both hemispheres, regions involved in bottom-up spectrotemporal analyses and top-down articulatory prediction and sensorimotor integration, respectively.

Insula-based networks in professional musicians: Evidence for increased functional connectivity during resting state fMRI

Despite considerable research on experience-dependent neuroplasticity in professional musicians, detailed understanding of an involvement of the insula is only now beginning to emerge. We investigated the effects of musical training on intrinsic insula-based connectivity in professional classical musicians relative to nonmusicians using resting-state functional MRI. Following a tripartite scheme of insula subdivisions, coactivation profiles were analyzed for the posterior, ventral anterior, and dorsal anterior insula in both hemispheres. While whole-brain connectivity across all participants confirmed previously reported patterns, between-group comparisons revealed increased insular connectivity in musicians relative to nonmusicians. Coactivated regions encompassed constituents of large-scale networks involved in salience detection (e.g., anterior and middle cingulate cortex), affective processing (e.g., orbitofrontal cortex and temporal pole), and higher order cognition (e.g., dorsolateral prefrontal cortex and the temporoparietal junction), whereas no differences were found for the reversed group contrast. Importantly, these connectivity patterns were stronger in musicians who experienced more years of musical practice, including also sensorimotor regions involved in music performance (M1 hand area, S1, A1, and SMA). We conclude that musical training triggers significant reorganization in insula-based networks, potentially facilitating high-level cognitive and affective functions associated with the fast integration of multisensory information in the context of music performance. Hum Brain Mapp 38:4834-4849, 2017. © 2017 Wiley Periodicals, Inc.

Diffusion tensor MRI tractography reveals increased fractional anisotropy (FA) in arcuate fasciculus following music-cued motor training

Auditory cues are frequently used to support movement learning and rehabilitation, but the neural basis of this behavioural effect is not yet clear. We investigated the microstructural neuroplasticity effects of adding musical cues to a motor learning task. We hypothesised that music-cued, left-handed motor training would increase fractional anisotropy (FA) in the contralateral arcuate fasciculus, a fibre tract connecting auditory, pre-motor and motor regions. Thirty right-handed participants were assigned to a motor learning condition either with (Music Group) or without (Control Group) musical cues. Participants completed 20minutes of training three times per week over four weeks. Diffusion tensor MRI and probabilistic neighbourhood tractography identified FA, axial (AD) and radial (RD) diffusivity before and after training. Results revealed that FA increased significantly in the right arcuate fasciculus of the Music group only, as hypothesised, with trends for AD to increase and RD to decrease, a pattern of results consistent with activity-dependent increases in myelination. No significant changes were found in the left ipsilateral arcuate fasciculus of either group. This is the first evidence that adding musical cues to movement learning can induce rapid microstructural change in white matter pathways in adults, with potential implications for therapeutic clinical practice.

Functional connectivity in resting state as a phonemic fluency ability measure

There is some evidence that functional connectivity (FC) measures obtained at rest may reflect individual differences in cognitive capabilities. We tested this possibility by using the FAS test as a measure of phonemic fluency. Seed regions of the main brain areas involved in this task were extracted from meta-analysis results (Wagner et al., 2014) and used for pairwise resting-state FC analysis. Ninety-three undergraduates completed the FAS test outside the scanner. A correlation analysis was conducted between the F-A-S scores (behavioral testing) and the pairwise FC pattern of verbal fluency regions of interest. Results showed that the higher FC between the thalamus and the cerebellum, and the lower FCs between the left inferior frontal gyrus and the right insula and between the supplementary motor area and the right insula were associated with better performance on the FAS test. Regression analyses revealed that the first two FCs contributed independently to this better phonemic fluency, reflecting a more general attentional factor (FC between thalamus and cerebellum) and a more specific fluency factor (FC between the left inferior frontal gyrus and the right insula). The results support the Spontaneous Trait Reactivation hypothesis, which explains how resting-state derived measures may reflect individual differences in cognitive abilities.

Error-related negativity in the skilled brain of pianists reveals motor simulation

Evidences have been provided of a crucial role of multimodal audio-visuomotor processing in subserving the musical ability. In this paper we investigated whether musical audiovisual stimulation might trigger the activation of motor information in the brain of professional pianists, due to the presence of permanent gestures/sound associations. At this aim EEG was recorded in 24 pianists and naive participants engaged in the detection of rare targets while watching hundreds of video clips showing a pair of hands in the act of playing, along with a compatible or incompatible piano soundtrack. Hands size and apparent distance allowed self-ownership and agency illusions, and therefore motor simulation. Event-related potentials (ERPs) and relative source reconstruction showed the presence of an Error-related negativity (ERN) to incongruent trials at anterior frontal scalp sites, only in pianists, with no difference in naïve participants. ERN was mostly explained by an anterior cingulate cortex (ACC) source. Other sources included "hands" IT regions, the superior temporal gyrus (STG) involved in conjoined auditory and visuomotor processing, SMA and cerebellum (representing and controlling motor subroutines), and regions involved in body parts representation (somatosensory cortex, uncus, cuneus and precuneus). The findings demonstrate that instrument-specific audiovisual stimulation is able to trigger error shooting and correction neural responses via motor resonance and mirroring, being a possible aid in learning and rehabilitation.