Wired for musical rhythm? A diffusion MRI-based study of individual differences in music perception

The Ramp protocol: Uncovering individual differences in walking to an auditory beat using TeensyStep

Intentionally walking to the beat of an auditory stimulus seems effortless for most humans. However, studies have revealed significant individual differences in the spontaneous tendency to synchronize. Some individuals tend to adapt their walking pace to the beat, while others show little or no adjustment. To fill this gap we introduce the Ramp protocol, which measures spontaneous adaptation to a change in an auditory rhythmic stimulus in a gait task. First, participants walk at their preferred cadence without stimulation. After several steps, a metronome is presented, timed to match the participant's heel-strike. Then, the metronome tempo progressively departs from the participant's cadence by either accelerating or decelerating. The implementation of the Ramp protocol required real-time detection of heel-strike and auditory stimuli aligned with participants' preferred cadence. To achieve this, we developed the TeensyStep device, which we validated compared to a gold standard for step detection. We also demonstrated the sensitivity of the Ramp protocol to individual differences in the spontaneous response to a tempo-changing rhythmic stimulus by introducing a new measure: the Response Score. This new method and quantification of spontaneous response to rhythmic stimuli holds promise for highlighting and distinguishing different profiles of adaptation in a gait task.

Frontoparietal network topology as a neural marker of musical perceptual abilities

Why are some individuals more musical than others? Neither cognitive testing nor classical localizationist neuroscience alone can provide a complete answer. Here, we test how the interplay of brain network organization and cognitive function delivers graded perceptual abilities in a distinctively human capacity. We analyze multimodal magnetic resonance imaging, cognitive, and behavioral data from 200+ participants, focusing on a canonical working memory network encompassing prefrontal and posterior parietal regions. Using graph theory, we examine structural and functional frontoparietal network organization in relation to assessments of musical aptitude and experience. Results reveal a positive correlation between perceptual abilities and the integration efficiency of key frontoparietal regions. The linkage between functional networks and musical abilities is mediated by working memory processes, whereas structural networks influence these abilities through sensory integration. Our work lays the foundation for future investigations into the neurobiological roots of individual differences in musicality.

Loop and Enjoy: A Scoping Review of the Research on the Effects of Processing Fluency on Aesthetic Reactions to Auditory Stimuli

Processing fluency has been shown to affect how people aesthetically evaluate stimuli. While this effect is well documented for visual stimuli, the evidence accumulated for auditory stimuli has not yet been integrated. Our aim was to examine the relevant research on how processing fluency affects the aesthetic appreciation of auditory stimuli and to identify the extant knowledge gaps in this body of evidence. This scoping review of 19 studies reported across 13 articles found that, similarly to visual stimuli, fluency has a positive effect on liking of auditory stimuli. Additionally, we identified certain elements that impede the generalizability of the current research on the relationship between fluency and aesthetic reactions to auditory stimuli, such as a lack of consistency in the number of repeated exposures, the tendency to omit the affective component and the failure to account for personal variables such as musical abilities developed through musical training or the participants' personality or preferences. These results offer a starting point in developing novel and proper processing fluency manipulations of auditory stimuli and suggest several avenues for future research aiming to clarify the impact and importance of processing fluency and disfluency in this domain.

Rhythmic musical activities may strengthen connectivity between brain networks associated with aging-related deficits in timing and executive functions

Brain aging and common conditions of aging (e.g., hypertension) affect networks important in organizing information, processing speed and action programming (i.e., executive functions). Declines in these networks may affect timing and could have an impact on the ability to perceive and perform musical rhythms. There is evidence that participation in rhythmic musical activities may help to maintain and even improve executive functioning (near transfer), perhaps due to similarities in brain regions underlying timing, musical rhythm perception and production, and executive functioning. Rhythmic musical activities may present as a novel and fun activity for older adults to stimulate interacting brain regions that deteriorate with aging. However, relatively little is known about neurobehavioral interactions between aging, timing, rhythm perception and production, and executive functioning. In this review, we account for these brain-behavior interactions to suggest that deeper knowledge of overlapping brain regions associated with timing, rhythm, and cognition may assist in designing more targeted preventive and rehabilitative interventions to reduce age-related cognitive decline and improve quality of life in populations with neurodegenerative disease. Further research is needed to elucidate the functional relationships between brain regions associated with aging, timing, rhythm perception and production, and executive functioning to direct design of targeted interventions.

Quality standards and recommendations for research in music and neuroplasticity

Research on how music influences brain plasticity has gained momentum in recent years. Considering, however, the nonuniform methodological standards implemented, the findings end up being nonreplicable and less generalizable. To address the need for a standardized baseline of research quality, we gathered all the studies in the music and neuroplasticity field in 2019 and appraised their methodological rigor systematically and critically. The aim was to provide a preliminary and, at the minimum, acceptable quality threshold-and, ipso facto, suggested recommendations-whereupon further discussion and development may take place. Quality appraisal was performed on 89 articles by three independent raters, following a standardized scoring system. The raters' scoring was cross-referenced following an inter-rater reliability measure, and further studied by performing multiple ratings comparisons and matrix analyses. The results for methodological quality were at a quite good level (quantitative articles: mean = 0.737, SD = 0.084; qualitative articles: mean = 0.677, SD = 0.144), following a moderate but statistically significant level of agreement between the raters (W = 0.44, χ² = 117.249, p = 0.020). We conclude that the standards for implementation and reporting are of high quality; however, certain improvements are needed to reach the stringent levels presumed for such an influential interdisciplinary scientific field.

Structural connectivity predicts sequential processing differences in music perception ability

To relate individual differences in music perception ability with whole brain white matter connectivity, we scanned a group of 27 individuals with varying degrees of musical training and assessed musical ability in sensory and sequential music perception domains using the Profile of Music Perception Skills-Short version (PROMS-S). Sequential processing ability was estimated by combining performance on tasks for Melody, Standard Rhythm, Embedded Rhythm, and Accent subscores while sensory processing ability was ascertained via tasks of Tempo, Pitch, Timbre, and Tuning. Controlling for musical training, gender, and years of training, network-based statistics revealed positive linear associations between total PROMS-S scores and increased interhemispheric fronto-temporal and parieto-frontal white matter connectivity, suggesting a distinct segregated structural network for music perception. Secondary analysis revealed two subnetworks for sequential processing ability, one comprising ventral fronto-temporal and subcortical regions and the other comprising dorsal fronto-temporo-parietal regions. A graph-theoretic analysis to characterize the structural network revealed a positive association of modularity of the whole brain structural connectome with the d' total score. In addition, the nodal degree of the right posterior cingulate cortex also showed a significant positive correlation with the total d' score. Our results suggest that a distinct structural network of connectivity across fronto-temporal, cerebellar, and cerebro-subcortical regions is associated with music processing abilities and the right posterior cingulate cortex mediates the connectivity of this network.

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.

Auditory and frontal anatomic correlates of pitch discrimination in musicians, non-musicians, and children without musical training

Individual differences in pitch discrimination have been associated with the volume of both the bilateral Heschl's gyrus and the right inferior frontal gyrus (IFG). However, most of these studies used samples composed of individuals with different amounts of musical training. Here, we investigated the relationship between pitch discrimination and individual differences in the gray matter (GM) volume of these brain structures in 32 adult musicians, 28 adult non-musicians, and 32 children without musical training. The results showed that (i) the individuals without musical training (whether children or adults) who were better at pitch discrimination had greater volume of auditory regions, whereas (ii) musicians with better pitch discrimination had greater volume of the IFG. These results suggest that the relationship between pitch discrimination and the volume of auditory regions is innately established early in life, and that musical training modulates the volume of the IFG, probably improving audio-motor connectivity. This is the first study to detect a relationship between pitch discrimination ability and GM volume before beginning any musical training in children and adults.

Relationship between Interhemispheric Inhibition and Dexterous Hand Performance in Musicians and Non-musicians

Interhemispheric inhibition (IHI) is essential for dexterous motor control. Small previous studies have shown differences in IHI in musicians compared to non-musicians, but it is not clear whether these differences are robustly linked to musical performance. In the largest study to date, we examined IHI and comprehensive measures of dexterous bimanual performance in 72 individuals (36 musicians and 36 non-musicians). Dexterous bimanual performance was quantified by speed, accuracy, and evenness derived from a series of hand tasks. As expected, musicians significantly outperformed non-musicians. Surprisingly, these performance differences could not be simply explained by IHI, as IHI did not significantly differ between musicians and non-musicians. However, canonical correlation analysis revealed a significant relationship between combinations of IHI and performance variables in the musician group. Specifically, we identified that IHI may contribute to the maintenance of evenness regardless of speed, a feature of musical performance that may be driven by practice with a metronome. Therefore, while IHI changes by themselves may not be sufficient to explain superior hand dexterity exhibited by musicians, IHI may be a potential neural correlate for specific features of musical performance.