What you learn & when you learn it: Impact of early bilingual & music experience on the structural characteristics of auditory-motor pathways

Neuroanatomical correlates of musicianship in left-handers

BACKGROUND

Left-handedness is a condition that reverses the typical left cerebral dominance of motor control to an atypical right dominance. The impact of this distinct control - and its associated neuroanatomical peculiarities - on other cognitive functions such as music processing or playing a musical instrument remains unexplored. Previous studies in right-handed population have linked musicianship to a larger volume in the (right) auditory cortex and a larger volume in the (right) arcuate fasciculus.

RESULTS

In our study, we reveal that left-handed musicians (n = 55), in comparison to left-handed non-musicians (n = 75), exhibit a larger gray matter volume in both the left and right Heschl's gyrus, critical for auditory processing. They also present a higher number of streamlines across the anterior segment of the right arcuate fasciculus. Importantly, atypical hemispheric lateralization of speech (notably prevalent among left-handers) was associated to a rightward asymmetry of the AF, in contrast to the leftward asymmetry exhibited by the typically lateralized.

CONCLUSIONS

These findings suggest that left-handed musicians share similar neuroanatomical characteristics with their right-handed counterparts. However, atypical lateralization of speech might potentiate the right audiomotor pathway, which has been associated with musicianship and better musical skills. This may help explain why musicians are more prevalent among left-handers and shed light on their cognitive advantages.

Positive or negative environmental modulations on human brain development: the morpho-functional outcomes of music training or stress

In the last couple of decades, the study of human living brain has benefitted of neuroimaging and non-invasive electrophysiological techniques, which are particularly valuable during development. A number of studies allowed to trace the usual stages leading from pregnancy to adult age, and relate them to functional and behavioral measurements. It was also possible to explore the effects of some interventions, behavioral or not, showing that the commonly followed pathway to adulthood may be steered by external interventions. These events may result in behavioral modifications but also in structural changes, in some cases limiting plasticity or extending/modifying critical periods. In this review, we outline the healthy human brain development in the absence of major issues or diseases. Then, the effects of negative (different stressors) and positive (music training) environmental stimuli on brain and behavioral development is depicted. Hence, it may be concluded that the typical development follows a course strictly dependent from environmental inputs, and that external intervention can be designed to positively counteract negative influences, particularly at young ages. We also focus on the social aspect of development, which starts in utero and continues after birth by building social relationships. This poses a great responsibility in handling children education and healthcare politics, pointing to social accountability for the responsible development of each child.

Exploring the Synergy of Music and Medicine in Healthcare: Expert Insights into the Curative and Societal Role of the Relationship between Music and Medicine

Our study aimed to investigate the correlation between medicine, health perception, and music as well as the role of music in the healthcare setting. To gain insights into the dynamics between these two fields, we gathered opinions from attendees and presenters at an international conference on music medicine, musicians' health, and music therapy. A team of six interviewers conducted a total of 26 semi-structured interviews. The interview guide focused on four predetermined themes: (1) "music in medicine", (2) "performing arts medicine", (3) "music for the individual", and (4) "music for society". The responses were analyzed using grounded theory methods as well as thematic and content analysis. To enhance the analytical strength, investigator triangulation was employed. Within the predefined themes, we identified several subthemes. Theme 1 encompassed topics such as "listening and performing music for treating diseases and establishing non-verbal relationships", "the value of music in specific disorders, end-of-life care, and pain management", and "the design of sound spaces". Theme 2 explored aspects including the "denial and taboo surrounding physical and mental health issues among musicians", "the importance of prevention", and an antithesis: "pain and suffering driving creativity". Theme 3 addressed the "mental role of music in ordinary and extraordinary life" as well as "music's ability to enable self-conditioning". Lastly, Theme 4 examined the role of music in "cultural self-identification" and "development and education for children". Throughout the interviews, participants expressed a lack of knowledge and awareness regarding interdisciplinary research and the fields of music and medicine. Our findings affirm the significance of music therapy and performing arts medicine as well as the broader relationship between music and medicine. They highlight the potential benefits of perception and experiential pathways for individuals and, consequently, for human society.

Pavlovian conditioning-induced hallucinations reduce MMN amplitudes for duration but not frequency deviants

The mismatch negativity (MMN) is an evoked potential that indexes auditory regularity violations. Since the 90's, a reduced amplitude of this brain activity in patients with schizophrenia has been consistently reported. Recently, this alteration has been related to the presence of auditory hallucinations (AHs) rather than the schizophrenia diagnostic per se. However, making this attribution is rather problematic due to the high heterogeneity of symptoms in schizophrenia. In an attempt to isolate the AHs influence on the MMN amplitude from other cofounding variables, we artificially induced AHs in a non-clinical population by Pavlovian conditioning. Before and after conditioning, volunteers (N = 31) participated in an oddball paradigm that elicited an MMN. Two different types of deviants were presented: a frequency and a duration deviant, as the MMN alteration seems to be especially present in schizophrenia with the latter type of deviant. Hence, this pre-post design allowed us to compare whether experiencing conditioning-induced AHs exert any influence on MMN amplitudes. Our results show that duration-deviant related MMN reductions significantly correlate with the number of AHs experienced. Moreover, we found a significant correlation between AHs proneness (measured with the Launay-Slade Hallucination Extended Scale) and the number of AHs experienced during the paradigm. In sum, our study shows that AHs can be conditioned and exert similar effects on MMN modulation in healthy participants as has been reported for patients with schizophrenia. Thus, conditioning paradigms offer the possibility to study the association between hallucinations and MMN reductions without the confounding variables present in schizophrenia patients.

Effects of Musical Classes on Motor Creativity According to Age, Sex, and Weight Status in Young Students: A Music-Oriented versus Conventional Education Plan

Motor creativity can be influenced by the specificity of the school-class environments (music-based education plans) and individual characteristics. This study aimed to investigate the effects of music oriented and conventional education plans on rhythmic perceptive capacity, motor creativity, and skill- and health-related fitness components in young students according to age, sex, and weight status. One hundred sixty-three young Italian students from elementary (second and fourth grade) and middle school (sixth and eighth grade) were enrolled in the study according to their education plan (music oriented or conventional). All participants were tested for rhythmic perceptive capacity (Stambak's test), motor creativity (Divergent Movement Ability test), skill-related (Körperkoordinationstest Für Kinder), and health-related (Multistage Fitness test) components. Individuals were also considered according to age (elementary and middle school), sex, and weight status. Significant age × education plan and sex × education plan interactions (p < 0.01) were found in motor creativity (locomotor and stability skills) and motor competence (balance and jumping-like activities). No significant weight status × education plan interaction was found. The predominant role of music in the music-oriented education plan appeared to foster the ability to enhance motor creativity in elementary and middle school students compared to the conventional plan. Moreover, music-oriented experience also seems relevant for expressing and exhibiting motor competence (i.e., balance) in relation to sex.

Neurological Music Therapy Rebuilds Structural Connectome after Traumatic Brain Injury: Secondary Analysis from a Randomized Controlled Trial

Background: Traumatic brain injury (TBI) is a common and devastating neurological condition, associated often with poor functional outcome and deficits in executive function. Due to the neuropathology of TBI, neuroimaging plays a crucial role in its assessment, and while diffusion MRI has been proposed as a sensitive biomarker, longitudinal studies evaluating treatment-related diffusion MRI changes are scarce. Recent evidence suggests that neurological music therapy can improve executive functions in patients with TBI and that these effects are underpinned by neuroplasticity changes in the brain. However, studies evaluating music therapy induced structural connectome changes in patients with TBI are lacking. Design: Single-blind crossover (AB/BA) randomized controlled trial (NCT01956136). Objective: Here, we report secondary outcomes of the trial and set out to assess the effect of neurological music therapy on structural white matter connectome changes and their association with improved execute function in patients with TBI. Methods: Using an AB/BA design, 25 patients with moderate or severe TBI were randomized to receive a 3-month neurological music therapy intervention either during the first (AB, n = 16) or second (BA, n = 9) half of a 6-month follow-up period. Neuropsychological testing and diffusion MRI scans were performed at baseline and at the 3-month and 6-month stage. Findings: Compared to the control group, the music therapy group increased quantitative anisotropy (QA) in the right dorsal pathways (arcuate fasciculus, superior longitudinal fasciculus) and in the corpus callosum and the right frontal aslant tract, thalamic radiation and corticostriatal tracts. The mean increased QA in this network of results correlated with improved executive function. Conclusions: This study shows that music therapy can induce structural white matter neuroplasticity in the post-TBI brain that underpins improved executive function.

Understanding Sensitive Period Effects in Musical Training

Adult ability in complex cognitive domains, including music, is commonly thought of as the product of gene-environment interactions, where genetic predispositions influence and are modulated by experience, resulting in the final phenotypic expression. Recently, however, the important contribution of maturation to gene-environment interactions has become better understood. Thus, the timing of exposure to specific experience, such as music training, has been shown to produce long-term impacts on adult behaviour and the brain. Work from our lab and others shows that musical training before the ages of 7-9 enhances performance on musical tasks and modifies brain structure and function, sometimes in unexpected ways. The goal of this paper is to present current evidence for sensitive period effects for musical training in the context of what is known about brain maturation and to present a framework that integrates genetic, environmental and maturational influences on the development of musical skill. We believe that this framework can also be applied more broadly to understanding how predispositions, brain development and experience interact.

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.

The Musical Ear Test: Norms and correlates from a large sample of Canadian undergraduates

We sought to establish norms and correlates for the Musical Ear Test (MET), an objective test of musical ability. A large sample of undergraduates at a Canadian university (N > 500) took the 20-min test, which provided a Total score as well as separate scores for its Melody and Rhythm subtests. On each trial, listeners judged whether standard and comparison auditory sequences were the same or different. Norms were derived as percentiles, Z-scores, and T-scores. The distribution of scores was approximately normal without floor or ceiling effects. There were no gender differences on either subtest or the total score. As expected, scores on both subtests were correlated with performance on a test of immediate recall for nonmusical auditory stimuli (Digit Span Forward). Moreover, as duration of music training increased, so did performance on both subtests, but starting lessons at a younger age was not predictive of better musical abilities. Listeners who spoke a tone language exhibited enhanced performance on the Melody subtest but not on the Rhythm subtest. The MET appears to have adequate psychometric characteristics that make it suitable for researchers who seek to measure musical abilities objectively.

Arcuate fasciculus architecture is associated with individual differences in pre-attentive detection of unpredicted music changes

The mismatch negativity (MMN) is an event related brain potential (ERP) elicited by unpredicted sounds presented in a sequence of repeated auditory stimuli. The neural sources of the MMN have been previously attributed to a fronto-temporo-parietal network which crucially overlaps with the so-called auditory dorsal stream, involving inferior and middle frontal, inferior parietal, and superior and middle temporal regions. These cortical areas are structurally connected by the arcuate fasciculus (AF), a three-branch pathway supporting the feedback-feedforward loop involved in auditory-motor integration, auditory working memory, storage of acoustic templates, as well as comparison and update of those templates. Here, we characterized the individual differences in the white-matter macrostructural properties of the AF and explored their link to the electrophysiological marker of passive change detection gathered in a melodic multifeature MMN-EEG paradigm in 26 healthy young adults without musical training. Our results show that left fronto-temporal white-matter connectivity plays an important role in the pre-attentive detection of rhythm modulations within a melody. Previous studies have shown that this AF segment is also critical for language processing and learning. This strong coupling between structure and function in auditory change detection might be related to life-time linguistic (and possibly musical) exposure and experiences, as well as to timing processing specialization of the left auditory cortex. To the best of our knowledge, this is the first time in which the relationship between neurophysiological (EEG) and brain white-matter connectivity indexes using DTI-tractography are studied together. Thus, the present results, although still exploratory, add to the existing evidence on the importance of studying the constraints imposed on cognitive functions by the underlying structural connectivity.