Cortico-cerebellar audio-motor regions coordinate self and other in musical joint action.

Joint music performance requires flexible sensorimotor coordination between self and other. Cognitive and sensory parameters of joint action-such as shared knowledge or temporal (a)synchrony-influence this coordination by shifting the balance between self-other segregation and integration. To investigate the neural bases of these parameters and their interaction during joint action, we asked pianists to play on an MR-compatible piano, in duet with a partner outside of the scanner room. Motor knowledge of the partner's musical part and the temporal compatibility of the partner's action feedback were manipulated. First, we found stronger activity and functional connectivity within cortico-cerebellar audio-motor networks when pianists had practiced their partner's part before. This indicates that they simulated and anticipated the auditory feedback of the partner by virtue of an internal model. Second, we observed stronger cerebellar activity and reduced behavioral adaptation when pianists encountered subtle asynchronies between these model-based anticipations and the perceived sensory outcome of (familiar) partner actions, indicating a shift towards self-other segregation. These combined findings demonstrate that cortico-cerebellar audio-motor networks link motor knowledge and other-produced sounds depending on cognitive and sensory factors of the joint performance, and play a crucial role in balancing self-other integration and segregation.

Neural tracking of visual periodic motion.

Periodicity is a fundamental property of biological systems, including human movement systems. Periodic movements support displacements of the body in the environment as well as interactions and communication between individuals. Here, we use electroencephalography (EEG) to investigate the neural tracking of visual periodic motion, and more specifically, the relevance of spatiotemporal information contained at and between their turning points. We compared EEG responses to visual sinusoidal oscillations versus nonlinear Rayleigh oscillations, which are both typical of human movements. These oscillations contain the same spatiotemporal information at their turning points but differ between turning points, with Rayleigh oscillations having an earlier peak velocity, shown to increase an individual's capacity to produce accurately synchronized movements. EEG analyses highlighted the relevance of spatiotemporal information between the turning points by showing that the brain precisely tracks subtle differences in velocity profiles, as indicated by earlier EEG responses for Rayleigh oscillations. The results suggest that the brain is particularly responsive to velocity peaks in visual periodic motion, supporting their role in conveying behaviorally relevant timing information at a neurophysiological level. The results also suggest key functions of neural oscillations in the Alpha and Beta frequency bands, particularly in the right hemisphere. Together, these findings provide insights into the neural mechanisms underpinning the processing of visual periodic motion and the critical role of velocity peaks in enabling proficient visuomotor synchronization.

Electrophysiological Activity from the Eye Muscles, Cerebellum and Cerebrum During Reflexive (Classical Pavlovian) Versus Voluntary (Ivanov-Smolensky) Eye-Blink Conditioning.

We report an experiment to investigate the role of the cerebellum and cerebrum in motor learning of timed movements. Eleven healthy human subjects were recruited to perform two experiments, the first was a classical eye-blink conditioning procedure with an auditory tone as conditional stimulus (CS) and vestibular unconditional stimulus (US) in the form of a double head-tap. In the second experiment, subjects were asked to blink voluntarily in synchrony with the double head-tap US preceded by a CS, a form of Ivanov-Smolensky conditioning in which a command or instruction is associated with the US. Electrophysiological recordings were made of extra-ocular EMG and EOG at infra-ocular sites (IO1/2), EEG from over the frontal eye fields (C3'/C4') and from over the posterior fossa over the cerebellum for the electrocerebellogram (ECeG). The behavioural outcomes of the experiments showed weak reflexive conditioning for the first experiment despite the double tap but robust, well-synchronised voluntary conditioning for the second. Voluntary conditioned blinks were larger than the reflex ones. For the voluntary conditioning experiment, a contingent negative variation (CNV) was also present in the EEG leads prior to movement, and modulation of the high-frequency EEG occurred during movement. US-related cerebellar activity was prominent in the high-frequency ECeG for both experiments, while conditioned response-related cerebellar activity was additionally present in the voluntary conditioning experiment. These results demonstrate a role for the cerebellum in voluntary (Ivanov-Smolensky) as well as in reflexive (classical Pavlovian) conditioning.

Sex-related communicative functions of voice spectral energy in human chorusing.

Music is a human communicative art whose evolutionary origins may lie in capacities that support cooperation and/or competition. A mixed account favouring simultaneous cooperation and competition draws on analogous interactive displays produced by collectively signalling non-human animals (e.g. crickets and frogs). In these displays, rhythmically coordinated calls serve as a beacon whereby groups of males 'cooperatively' attract potential female mates, while the likelihood of each male competitively attracting an actual mate depends on the precedence of his signal. Human behaviour consistent with the mixed account was previously observed in a renowned boys choir, where the basses-the oldest boys with the deepest voices-boosted their acoustic prominence by increasing energy in a high-frequency band of the vocal spectrum when girls were in an otherwise male audience. The current study tested female and male sensitivity and preferences for this subtle vocal modulation in online listening tasks. Results indicate that while female and male listeners are similarly sensitive to enhanced high-spectral energy elicited by the presence of girls in the audience, only female listeners exhibit a reliable preference for it. Findings suggest that human chorusing is a flexible form of social communicative behaviour that allows simultaneous group cohesion and sexually motivated competition.

Spatial and temporal (non)binding of audiovisual rhythms in sensorimotor synchronisation.

Human movement synchronisation with moving objects strongly relies on visual input. However, auditory information also plays an important role, since real environments are intrinsically multimodal. We used electroencephalography (EEG) frequency tagging to investigate the selective neural processing and integration of visual and auditory information during motor tracking and tested the effects of spatial and temporal congruency between audiovisual modalities. EEG was recorded while participants tracked with their index finger a red flickering (rate fV = 15 Hz) dot oscillating horizontally on a screen. The simultaneous auditory stimulus was modulated in pitch (rate fA = 32 Hz) and lateralised between left and right audio channels to induce perception of a periodic displacement of the sound source. Audiovisual congruency was manipulated in terms of space in Experiment 1 (no motion, same direction or opposite direction), and timing in Experiment 2 (no delay, medium delay or large delay). For both experiments, significant EEG responses were elicited at fV and fA tagging frequencies. It was also hypothesised that intermodulation products corresponding to the nonlinear integration of visual and auditory stimuli at frequencies fV ± fA would be elicited, due to audiovisual integration, especially in Congruent conditions. However, these components were not observed. Moreover, synchronisation and EEG results were not influenced by congruency manipulations, which invites further exploration of the conditions which may modulate audiovisual processing and the motor tracking of moving objects.

Infants show enhanced neural responses to musical meter frequencies beyond low-level features.

Music listening often entails spontaneous perception and body movement to a periodic pulse-like meter. There is increasing evidence that this cross-cultural ability relates to neural processes that selectively enhance metric periodicities, even when these periodicities are not prominent in the acoustic stimulus. However, whether these neural processes emerge early in development remains largely unknown. Here, we recorded the electroencephalogram (EEG) of 20 healthy 5- to 6-month-old infants, while they were exposed to two rhythms known to induce the perception of meter consistently across Western adults. One rhythm contained prominent acoustic periodicities corresponding to the meter, whereas the other rhythm did not. Infants showed significantly enhanced representations of meter periodicities in their EEG responses to both rhythms. This effect is unlikely to reflect the tracking of salient acoustic features in the stimulus, as it was observed irrespective of the prominence of meter periodicities in the audio signals. Moreover, as previously observed in adults, the neural enhancement of meter was greater when the rhythm was delivered by low-pitched sounds. Together, these findings indicate that the endogenous enhancement of metric periodicities beyond low-level acoustic features is a neural property that is already present soon after birth. These high-level neural processes could set the stage for internal representations of musical meter that are critical for human movement coordination during rhythmic musical behavior. RESEARCH HIGHLIGHTS: 5- to 6-month-old infants were presented with auditory rhythms that induce the perception of a periodic pulse-like meter in adults. Infants showed selective enhancement of EEG activity at meter-related frequencies irrespective of the prominence of these frequencies in the stimulus. Responses at meter-related frequencies were boosted when the rhythm was conveyed by bass sounds. High-level neural processes that transform rhythmic auditory stimuli into internal meter templates emerge early after birth.

Endogenous sources of interbrain synchrony in duetting pianists.

When people interact with each other, their brains synchronize. However, it remains unclear whether interbrain synchrony (IBS) is functionally relevant for social interaction or stems from exposure of individual brains to identical sensorimotor information. To disentangle these views, the current dual-EEG study investigated amplitude-based IBS in pianists jointly performing duets containing a silent pause followed by a tempo change. First, we manipulated the similarity of the anticipated tempo change and measured IBS during the pause, hence, capturing the alignment of purely endogenous, temporal plans without sound or movement. Notably, right posterior gamma IBS was higher when partners planned similar tempi, it predicted whether partners' tempi matched after the pause, and it was modulated only in real, not in surrogate pairs. Second, we manipulated the familiarity with the partner's actions and measured IBS during joint performance with sound. Although sensorimotor information was similar across conditions, gamma IBS was higher when partners were unfamiliar with each other's part and had to attend more closely to the sound of the performance. These combined findings demonstrate that IBS is not merely an epiphenomenon of shared sensorimotor information but can also hinge on endogenous, cognitive processes crucial for behavioral synchrony and successful social interaction.

Lateral prefrontal cortex is a hub for music production from structural rules to movements.

Complex sequential behaviors, such as speaking or playing music, entail flexible rule-based chaining of single acts. However, it remains unclear how the brain translates abstract structural rules into movements. We combined music production with multimodal neuroimaging to dissociate high-level structural and low-level motor planning. Pianists played novel musical chord sequences on a muted MR-compatible piano by imitating a model hand on screen. Chord sequences were manipulated in terms of musical harmony and context length to assess structural planning, and in terms of fingers used for playing to assess motor planning. A model of probabilistic sequence processing confirmed temporally extended dependencies between chords, as opposed to local dependencies between movements. Violations of structural plans activated the left inferior frontal and middle temporal gyrus, and the fractional anisotropy of the ventral pathway connecting these two regions positively predicted behavioral measures of structural planning. A bilateral frontoparietal network was instead activated by violations of motor plans. Both structural and motor networks converged in lateral prefrontal cortex, with anterior regions contributing to musical structure building, and posterior areas to movement planning. These results establish a promising approach to study sequence production at different levels of action representation.

Dynamic modulation of cortico-muscular coupling during real and imagined sensorimotor synchronisation.

People have a natural and intrinsic ability to coordinate body movements with rhythms surrounding them, known as sensorimotor synchronisation. This can be observed in daily environments, when dancing or singing along with music, or spontaneously walking, talking or applauding in synchrony with one another. However, the neurophysiological mechanisms underlying accurately synchronised movement with selected rhythms in the environment remain unclear. Here we studied real and imagined sensorimotor synchronisation with interleaved auditory and visual rhythms using cortico-muscular coherence (CMC) to better understand the processes underlying the preparation and execution of synchronised movement. Electroencephalography (EEG), electromyography (EMG) from the finger flexors, and continuous force signals were recorded in 20 participants during tapping and imagined tapping with discrete stimulus sequences consisting of alternating auditory beeps and visual flashes. The results show that the synchronisation between cortical and muscular activity in the beta (14-38 Hz) frequency band becomes time-locked to the taps executed in synchrony with the visual and auditory stimuli. Dynamic modulation in CMC also occurred when participants imagined tapping with the visual stimuli, but with lower amplitude and a different temporal profile compared to real tapping. These results suggest that CMC does not only reflect changes related to the production of the synchronised movement, but also to its preparation, which appears heightened under higher attentional demands imposed when synchronising with the visual stimuli. These findings highlight a critical role of beta band neural oscillations in the cortical-muscular coupling underlying sensorimotor synchronisation.

Neural tracking of the musical beat is enhanced by low-frequency sounds.

Music makes us move, and using bass instruments to build the rhythmic foundations of music is especially effective at inducing people to dance to periodic pulse-like beats. Here, we show that this culturally widespread practice may exploit a neurophysiological mechanism whereby low-frequency sounds shape the neural representations of rhythmic input by boosting selective locking to the beat. Cortical activity was captured using electroencephalography (EEG) while participants listened to a regular rhythm or to a relatively complex syncopated rhythm conveyed either by low tones (130 Hz) or high tones (1236.8 Hz). We found that cortical activity at the frequency of the perceived beat is selectively enhanced compared with other frequencies in the EEG spectrum when rhythms are conveyed by bass sounds. This effect is unlikely to arise from early cochlear processes, as revealed by auditory physiological modeling, and was particularly pronounced for the complex rhythm requiring endogenous generation of the beat. The effect is likewise not attributable to differences in perceived loudness between low and high tones, as a control experiment manipulating sound intensity alone did not yield similar results. Finally, the privileged role of bass sounds is contingent on allocation of attentional resources to the temporal properties of the stimulus, as revealed by a further control experiment examining the role of a behavioral task. Together, our results provide a neurobiological basis for the convention of using bass instruments to carry the rhythmic foundations of music and to drive people to move to the beat.

Oxytocin as an allostatic agent in the social bonding effects of music.

Despite acknowledging that musicality evolved to serve multiple adaptive functions in human evolution, Savage et al. promote social bonding to an overarching super-function. Yet, no unifying neurobiological framework is offered. We propose that oxytocin constitutes a socio-allostatic agent whose modulation of sensing, learning, prediction, and behavioral responses with reference to the physical and social environment facilitates music's social bonding effects.

Accent-induced Modulation of Neural and Movement Patterns during Spontaneous Synchronization to Auditory Rhythms.

Human rhythmic movements spontaneously synchronize with auditory rhythms at various frequency ratios. The emergence of more complex relationships-for instance, frequency ratios of 1:2 and 1:3-is enhanced by adding a congruent accentuation pattern (binary for 1:2 and ternary for 1:3), resulting in a 1:1 movement-accentuation relationship. However, this benefit of accentuation on movement synchronization appears to be stronger for the ternary pattern than for the binary pattern. Here, we investigated whether this difference in accent-induced movement synchronization may be related to a difference in the neural tracking of these accentuation profiles. Accented and control unaccented auditory sequences were presented to participants who concurrently produced finger taps at their preferred frequency, and spontaneous movement synchronization was measured. EEG was recorded during passive listening to each auditory sequence. The results revealed that enhanced movement synchronization with ternary accentuation was accompanied by enhanced neural tracking of this pattern. Larger EEG responses at the accentuation frequency were found for the ternary pattern compared with the binary pattern. Moreover, the amplitude of accent-induced EEG responses was positively correlated with the magnitude of accent-induced movement synchronization across participants. Altogether, these findings show that the dynamics of spontaneous auditory-motor synchronization is strongly driven by the multi-time-scale sensory processing of auditory rhythms, highlighting the importance of considering neural responses to rhythmic sequences for understanding and enhancing synchronization performance.

Neural tracking and integration of 'self' and 'other' in improvised interpersonal coordination.

Humans coordinate their movements with one another in a range of everyday activities and skill domains. Optimal joint performance requires the continuous anticipation of and adaptation to each other's movements, especially when actions are spontaneous rather than pre-planned. Here we employ dual-EEG and frequency-tagging techniques to investigate how the neural tracking of self- and other-generated movements supports interpersonal coordination during improvised motion. LEDs flickering at 5.7 and 7.7 Hz were attached to participants' index fingers in 28 dyads as they produced novel patterns of synchronous horizontal forearm movements. EEG responses at these frequencies revealed enhanced neural tracking of self-generated movement when leading and of other-generated movements when following. A marker of self-other integration at 13.4 Hz (inter-modulation frequency of 5.7 and 7.7 Hz) peaked when no leader was designated, and mutual adaptation and movement synchrony were maximal. Furthermore, the amplitude of EEG responses reflected differences in the capacity of dyads to synchronize their movements, offering a neurophysiologically grounded perspective for understanding perceptual-motor mechanisms underlying joint action.

Effects of pitch and tempo of auditory rhythms on spontaneous movement entrainment and stabilisation.

Human movements spontaneously entrain to auditory rhythms, which can help to stabilise movements in time and space. The properties of auditory rhythms supporting the occurrence of this phenomenon, however, remain largely unclear. Here, we investigate in two experiments the effects of pitch and tempo on spontaneous movement entrainment and stabilisation. We examined spontaneous entrainment of hand-held pendulum swinging in time with low-pitched (100 Hz) and high-pitched (1600 Hz) metronomes to test whether low pitch favours movement entrainment and stabilisation. To investigate whether stimulation and movement tempi moderate these effects of pitch, we manipulated (1) participants' preferred movement tempo by varying pendulum mechanical constraints (Experiment 1) and (2) stimulation tempo, which was either equal to, or slightly slower or faster (± 10%) than the participant's preferred movement tempo (Experiment 2). The results showed that participants' movements spontaneously entrained to auditory rhythms, and that this effect was stronger with low-pitched rhythms independently of stimulation and movement tempi. Results also indicated that auditory rhythms can lead to increased movement amplitude and stabilisation of movement tempo and amplitude, particularly when low-pitched. However, stabilisation effects were found to depend on intrinsic movement variability. Auditory rhythms decreased movement variability of individuals with higher intrinsic variability but increased movement variability of individuals with lower intrinsic variability. These findings provide new insights into factors that influence auditory-motor entrainment and how they may be optimised to enhance movement efficiency.

Your move or mine? Music training and kinematic compatibility modulate synchronization with self- versus other-generated dance movement.

Motor simulation has been implicated in how musicians anticipate the rhythm of another musician's action to achieve interpersonal synchronization. Here, we investigated whether similar mechanisms govern a related form of rhythmic action: dance. We examined (1) whether synchronization with visual dance stimuli was influenced by movement agency, (2) whether music training modulated simulation efficiency, and (3) what cues were relevant for simulating the dance rhythm. Participants were first recorded dancing the basic Charleston steps paced by a metronome, and later in a synchronization task they tapped to the rhythm of their own point-light dance stimuli, stimuli of another physically matched participant or one matched in movement kinematics, and a quantitative average across individuals. Results indicated that, while there was no overall "self advantage" and synchronization was generally most stable with the least variable (averaged) stimuli, motor simulation was driven-indicated by high tap-beat variability correlations-by familiar movement kinematics rather than morphological features. Furthermore, music training facilitated simulation, such that musicians outperformed non-musicians when synchronizing with others' movements but not with their own movements. These findings support action simulation as underlying synchronization in dance, linking action observation and rhythm processing in a common motor framework.

When the rhythm disappears and the mind keeps dancing: sustained effects of attentional entrainment.

Research has demonstrated that the human cognitive system allocates attention most efficiently to a stimulus that occurs in synchrony with an established rhythmic background. However, our environment is dynamic and constantly changing. What happens when rhythms to which our cognitive system adapted disappear? We addressed this question using a visual categorization task comprising emotional and neutral faces. The task was split into three blocks of which the first and the last were completed in silence. The second block was accompanied by an acoustic background rhythm that, for one group of participants, was synchronous with face presentations, and for another group was asynchronous. Irrespective of group, performance improved with background stimulation. Importantly, improved performance extended into the third silent block for the synchronous, but not for the asynchronous group. These data suggest that attentional entrainment resulting from rhythmic environmental regularities disintegrates only gradually after the regularities disappear.

Accent-induced stabilization of spontaneous auditory-motor synchronization.

Humans spontaneously synchronize their movements with external auditory rhythms such as a metronome or music. Although such synchronization preferentially occurs toward a simple 1:1 movement-sound frequency ratio, the parameters facilitating spontaneous synchronization to more complex frequency ratios remain largely unclear. The present study investigates the dynamics of spontaneous auditory-motor synchronization at a range of frequency ratios between movement and sound, and examines the benefit of simple accentuation pattern on synchronization emergence and stability. Participants performed index finger oscillations at their preferred tempo while listening to a metronome presented at either their preferred tempo, or twice or three times faster (frequency ratios of 1:1, 1:2 or 1:3) with different patterns of accentuation (unaccented, binary or ternary accented), and no instruction to synchronize. Participants' movements were spontaneously entrained to the auditory stimuli in the three different frequency ratio conditions. Moreover, the emergence and stability of the modes of coordination were influenced by the interaction between frequency ratio and pattern of accentuation. Coherent patterns, such as a 1:3 frequency ratio supported by a ternary accentuation, facilitated the emergence and stability of the corresponding mode of coordination. Furthermore, ternary accentuation induced a greater gain in stability for the corresponding mode of coordination than was observed with binary accentuation. Together, these findings demonstrate the importance of matching accentuation pattern and movement tempo for enhanced synchronization, opening new perspectives for stabilizing complex rhythmic motor behaviors, such as running.

The influence of pacer-movement continuity and pattern matching on auditory-motor synchronisation.

People commonly move along with auditory rhythms in the environment. Although the processes underlying such sensorimotor synchronisation have been extensively investigated in the previous research, the properties of auditory rhythms that facilitate the synchronisation remain largely unclear. This study explored the possible benefits of a continuity matching between auditory pacers and the movement produced as well as of a spatial pattern matching that has been previously demonstrated with visual pacers. Participants synchronised either finger tapping or forearm oscillations with either discrete or continuous pacers. The pacers had either a spatial pattern (left-right panning) that matched the movement pattern produced or no spatial pattern. The accuracy and variability of synchronisation were assessed by the mean and standard deviation of the asynchronies, respectively, between participant's movement and the pacers. Results indicated that synchronisation was more accurate and less variable for discrete pacers and continuous movement (i.e., forearm oscillations). The interaction between those two factors involved a more complex relationship than a simple continuity match benefit. Although synchronisation variability increased with continuous pacers for both types of movement, this increase was smaller for continuous movement than discrete movement, suggesting that continuous movement is more beneficial only for continuous pacers. Moreover, the results revealed limited benefits of spatial pattern matching on auditory-motor synchronisation variability, which might be due to lower spatial resolution of the auditory sensory modality. Together, these findings confirm that sensorimotor synchronisation is modulated by complex relations between pacer and movement properties.

Tutorial and simulations with ADAM: an adaptation and anticipation model of sensorimotor synchronization.

Interpersonal coordination of movements often involves precise synchronization of action timing, particularly in expert domains such as ensemble music performance. According to the adaptation and anticipation model (ADAM) of sensorimotor synchronization, precise yet flexible interpersonal coordination is supported by reactive error correction mechanisms and anticipatory mechanisms that exploit systematic patterns in stimulus timing to plan future actions. Here, we provide a tutorial introduction to the computational architecture of ADAM and present a series of single- and dual-virtual agent simulations that examine the model parameters that produce ideal synchronization performance in different tempo conditions. In the single-agent simulations, a virtual agent synchronized responses to steady tempo sequence or a sequence containing gradual tempo changes. Parameters controlling basic reactive error (phase) correction were sufficient for producing ideal synchronization performance at the steady tempo, whereas parameters controlling anticipatory mechanisms were necessary for ideal performance with a tempo-changing sequence. In the dual-agent simulations, two interacting virtual agents produced temporal sequences from either congruent or incongruent internal performance templates specifying a steady tempo or tempo changes. Ideal performance was achieved with reactive error correction alone when both agents implemented the same performance template (either steady tempo or tempo change). In contrast, anticipatory mechanisms played a key role when one agent implemented a steady tempo template and the other agent implemented a tempo change template. These findings have implications for understanding the interplay between reactive and anticipatory mechanisms when agents possess compatible versus incompatible representations of task goals during human-human and human-machine interaction.

Neural bases of rhythmic entrainment in humans: critical transformation between cortical and lower-level representations of auditory rhythm.

The spontaneous ability to entrain to meter periodicities is central to music perception and production across cultures. There is increasing evidence that this ability involves selective neural responses to meter-related frequencies. This phenomenon has been observed in the human auditory cortex, yet it could be the product of evolutionarily older lower-level properties of brainstem auditory neurons, as suggested by recent recordings from rodent midbrain. We addressed this question by taking advantage of a new method to simultaneously record human EEG activity originating from cortical and lower-level sources, in the form of slow (< 20 Hz) and fast (> 150 Hz) responses to auditory rhythms. Cortical responses showed increased amplitudes at meter-related frequencies compared to meter-unrelated frequencies, regardless of the prominence of the meter-related frequencies in the modulation spectrum of the rhythmic inputs. In contrast, frequency-following responses showed increased amplitudes at meter-related frequencies only in rhythms with prominent meter-related frequencies in the input but not for a more complex rhythm requiring more endogenous generation of the meter. This interaction with rhythm complexity suggests that the selective enhancement of meter-related frequencies does not fully rely on subcortical auditory properties, but is critically shaped at the cortical level, possibly through functional connections between the auditory cortex and other, movement-related, brain structures. This process of temporal selection would thus enable endogenous and motor entrainment to emerge with substantial flexibility and invariance with respect to the rhythmic input in humans in contrast with non-human animals.