Published papers

The pleasurable urge to move in response to music is called groove. Prior research has suggested a potential link between groove and dopamine function. However, no studies to date have directly investigated the relationship between the two. Here, we aimed to assess individual dopamine function in the substantia nigra of healthy individuals using neuromelanin-sensitive magnetic resonance imaging (NM-MRI), a non-invasive method associated with dopamine function, and to investigate the relationship between the individual dopamine proxy index and sensitivity to the groove experience. In this study, 15 younger (< 48 years) and 16 older (≧48 years) healthy individuals participated. Participants listened to ten musical excerpts and rated the groove experience based on “pleasure” and “wanting to move.” To assess whether the groove experience is related to NM levels, type of musical excerpts, and sex, we analyzed with linear mixed-effects regression models. The results showed that higher NM levels (p = 0.032) and male sex (p = 0.034) were associated with higher pleasure ratings in the younger group. For the “urge to move” ratings, type of musical excerpts was associated with ratings in both groups (ps < 0.001), where high-groove music (Janata et al., 2012) receiving higher ratings. Taken together, these results suggest that the “pleasure” aspect of the groove experience in younger individuals was related to dopamine levels in the substantia nigra, but may not be associated with the “urge to move.” Thus, pleasure and the urge to move are likely to involve distinct dopaminergic pathways and mechanisms, warranting further investigation.

In opera singing competitions, judges use an overall score to evaluate the singers’ voices and determine their rankings. This score not only guides the singers’ technique and expressiveness, but also serves as a crucial indicator that can significantly influence their careers. However, the specific elements captured by this overall score remain unclear. To address this gap, the present study analyzed opera singing recordings to identify factors that explain the overall score. Ten trained female Japanese singers performed “Caro mio ben” under standardized recording conditions. Four experts evaluated the recorded performances by assigning an overall score of 100 points and rating six vocal attributes: vibrato, resonance, timbre, diction, intonation, and expressiveness. The recordings were then analyzed to calculate the acoustic features, including the singing power ratio (SPR), harmonic-to-noise ratio, and sound pressure level. We developed two linear mixed models: the first regressed the overall score on the subjective vocal attributes, whereas the second predicted the overall score from the acoustic features. Evaluator identity was included as a random effect in both models. The results showed that vibrato was a significant predictor of the overall score in the first model. In the second model, only SPR emerged as a significant predictor. These findings suggest that vibrato, which reflects emotional expressiveness and vocal control, and SPR, which indicates the relative power in the high-frequency band (2–4 kHz) and signifies a voice clearer than the accompaniment, are key factors in explaining the overall score in opera singing.

Glutamatergic dysfunction is involved in the pathophysiology of treatment-resistant depression (TRD). However, few physiological studies have evaluated its pathophysiology in vivo in individuals with TRD. Transcranial magnetic stimulation-electroencephalography (TMS-EEG) techniques can assess intracortical facilitation (ICF), which reflects glutamatergic neurophysiological function in specific cortical regions. The objectives of this study were (1) to compare glutamatergic receptor-mediated function as indexed with ICF TMS-EEG in the dorsolateral prefrontal cortex (DLPFC) between participants with TRD and healthy controls (HCs) and (2) to explore the relationships between cell-specific gene expression levels and the group difference in glutamatergic neural propagation using virtual histology approach. Sixty participants with TRD and thirty HCs were examined with ICF TMS-EEG measure (80 single-pulse TMS and paired-pulse ICF) in the left DLPFC. Both sensor and source-level ICF measures were computed to compare them between the TRD and HC groups. Furthermore, we conducted spatial correlation analyses interregionally between ICF glutamatergic activity and cell-specific gene expression levels employing the Allen Human Brain Atlas dataset. DLPFC-ICF at the sensor level was not significantly different between the two groups, whereas DLPFC-ICF at the source level was reduced in the TRD group compared with the HC group (p = 0.026). Moreover, the reduced ICF signal propagation of TRD correlated with astrocyte-specific gene expression level (p < 0.0001). The glutamatergic neural activities indexed by ICF in the left DLPFC were decreased in participants with TRD. Additionally, a relative reduction in glutamatergic signal propagation originating from the DLPFC in TRD may be associated with astrocytic abnormality.

Musical performances, particularly drumming, intricately balance rhythmic patterns and creative expression, all heavily influenced by the concept of 'groove'. This study explored how the brain learns and internalizes complex rhythms and grooves from a computational perspective. The cerebellum and basal ganglia play key roles in rhythm perception, production, and timing. We utilized an oscillation-driven reservoir computing model, which is a simplified recurrent neural network designed for timing learning, to acquire complex rhythms. The model was trained to replicate the drumming style of Jeff Porcaro by learning his hi-hat patterns. Analyses revealed that the model's outputs, including fluctuations in interbeat timings and amplitudes, were similar to the original drumming. Next, it was trained to generate multidimensional drum kit performances for various genres (funk, jazz, samba, and rock). Model outputs had timing deviation and audio features related to a sense of groove, similar to the original performances. By incorporating the oscillations of multiple frequencies into the reservoir, the model reproduced fluctuations of timing intervals (microtiming) and amplitudes, as well as audio features of each musical genre. Our results indicated that oscillation-driven reservoir computing can successfully replicate the timing and rhythmic complexity of professional drumming, suggesting that it is a common computational principle for motor timing and rhythm generation. Furthermore, this approach offers insights into the neural underpinnings of musical groove, shedding light on how the brain processes and reproduces intricate rhythmic patterns.

Both music and language are found in all known human societies, yet no studies have compared similarities and differences between song, speech, and instrumental music on a global scale. In this Registered Report, we analyzed two global datasets: (i) 300 annotated audio recordings representing matched sets of traditional songs, recited lyrics, conversational speech, and instrumental melodies from our 75 coauthors speaking 55 languages; and (ii) 418 previously published adult-directed song and speech recordings from 209 individuals speaking 16 languages. Of our six preregistered predictions, five were strongly supported: Relative to speech, songs use (i) higher pitch, (ii) slower temporal rate, and (iii) more stable pitches, while both songs and speech used similar (iv) pitch interval size and (v) timbral brightness. Exploratory analyses suggest that features vary along a “musi-linguistic” continuum when including instrumental melodies and recited lyrics. Our study provides strong empirical evidence of cross-cultural regularities in music and speech.

Task-specific focal dystonia (TSFD), characterized by the loss of fine motor control and coordination, affects drummers’ lower-limb movements, yet it remains relatively understudied, leaving a gap in understanding its effects on drumming performance and underlying muscle activities. This study explores lower limb dystonia’s impact on drumming performance and underlying muscle activity in a professional rock drummer. The drummer executed an eight-beat pattern on a drum kit, emphasizing kicking the bass drum on the initial beat and performing syncopation of the third beat. Dystonia symptoms primarily manifested in the initial beat, with fewer symptoms on syncopation of the third beat. Analysis revealed decreased bass-drum sound peak amplitude during the initial beat and increased (becoming more negative) synchronization error. Electromyographic (EMG) measurements of ten muscles in the affected right lower limb showed significant changes in the Biceps Femoris (BF), Tibialis Anterior (TA), Extensor Digitorum Longus (EDL), and Extensor Digitorum Brevis (EDB) muscles during symptom onset. Notably, we observed 1) earlier overactivation of the TA and EDL muscles during the leg lift-up motion or preparatory phase of pedaling, 2) reduced activation of the EDB muscle, and 3) increased activation of the BF muscle during the final pedaling movement when symptoms occurred. These findings suggest that lower-limb dystonia symptoms are characterized by a reduction in amplitude and an increase in synchronization error, potentially due to premature overactivation of the ankle dorsiflexor muscles.

When listening to music, we naturally move our bodies rhythmically to the beat, which can be pleasurable and difficult to resist. This pleasurable sensation of wanting to move the body to music has been called "groove." Following pioneering humanities research, psychological and neuroscientific studies have provided insights on associated musical features, behavioral responses, phenomenological aspects, and brain structural and functional correlates of the groove experience. Groove research has advanced the field of music science and more generally informed our understanding of bidirectional links between perception and action, and the role of the motor system in prediction. Activity in motor and reward-related brain networks during music listening is associated with the groove experience, and this neural activity is linked to temporal prediction and learning. This article reviews research on groove as a psychological phenomenon with neurophysiological correlates that link musical rhythm perception, sensorimotor prediction, and reward processing. Promising future research directions range from elucidating specific neural mechanisms to exploring clinical applications and socio-cultural implications of groove.

This study aimed to clarify the relationship between autistic traits and letter information processing, specifically, the components of faces when attention is paid to face-like information. We created a new “henohenomoheji-type compound stimulus,” in which letters are placed in positions in such a way as to resemble a face. In Experiment 1, we examined the relationship between autistic traits and the participants’ performance in a letter-recognition task in which a henohenomoheji-type compound stimulus was used. The results showed a significant moderate negative correlation between Autism-Spectrum Quotient-Japanese Version (AQ-J) scores and letter-recognition sensitivity when the compound stimuli were arranged like a face. The letter-detection task was employed in Experiment 2 to examine how autistic traits affect tasks' performance with a lower cognitive load than in Experiment 1. We found no correlation between AQ-J scores and letter-detection sensitivity with or without face-like features. These results suggest that paying attention to faces reduces the participants’ performance in letter recognition, which represents a higher cognitive load in individuals with higher autistic traits. A major implication of this study is that the henohenomoheji-type compound stimuli can be applied to several cognitive tasks, such as cognitive processing in individuals with autistic traits.