Hyper-brain hyper-frequency network topology dynamics when playing guitar in quartet.

Ensemble music performance is a highly coordinated form of social behavior requiring not only precise motor actions but also synchronization of different neural processes both within and between the brains of ensemble players. In previous analyses, which were restricted to within-frequency coupling (WFC), we showed that different frequencies participate in intra- and inter-brain coordination, exhibiting distinct network topology dynamics that underlie coordinated actions and interactions. However, many of the couplings both within and between brains are likely to operate across frequencies. Hence, to obtain a more complete picture of hyper-brain interaction when musicians play the guitar in a quartet, cross-frequency coupling (CFC) has to be considered as well. Furthermore, WFC and CFC can be used to construct hyper-brain hyper-frequency networks (HB-HFNs) integrating all the information flows between different oscillation frequencies, providing important details about ensemble interaction in terms of network topology dynamics (NTD). Here, we reanalyzed EEG (electroencephalogram) data obtained from four guitarists playing together in quartet to explore changes in HB-HFN topology dynamics and their relation to acoustic signals of the music. Our findings demonstrate that low-frequency oscillations (e.g., delta, theta, and alpha) play an integrative or pacemaker role in such complex networks and that HFN topology dynamics are specifically related to the guitar quartet playing dynamics assessed by sound properties. Simulations by link removal showed that the HB-HFN is relatively robust against loss of connections, especially when the strongest connections are preserved and when the loss of connections only affects the brain of one guitarist. We conclude that HB-HFNs capture neural mechanisms that support interpersonally coordinated action and behavioral synchrony.

A practical guide to EEG hyperscanning in joint action research: from motivation to implementation.

Developments in cognitive neuroscience have led to the emergence of hyperscanning, the simultaneous measurement of brain activity from multiple people. Hyperscanning is useful for investigating social cognition, including joint action, because of its ability to capture neural processes that occur within and between people as they coordinate actions toward a shared goal. Here, we provide a practical guide for researchers considering using hyperscanning to study joint action and seeking to avoid frequently raised concerns from hyperscanning skeptics. We focus specifically on Electroencephalography (EEG) hyperscanning, which is widely available and optimally suited for capturing fine-grained temporal dynamics of action coordination. Our guidelines cover questions that are likely to arise when planning a hyperscanning project, ranging from whether hyperscanning is appropriate for answering one's research questions to considerations for study design, dependent variable selection, data analysis and visualization. By following clear guidelines that facilitate careful consideration of the theoretical implications of research design choices and other methodological decisions, joint action researchers can mitigate interpretability issues and maximize the benefits of hyperscanning paradigms.

Interbrain substrates of role switching during mother-child interaction.

Mother-child interaction is highly dynamic and reciprocal. Switching roles in these back-and-forth interactions serves as a crucial feature of reciprocal behaviors while the underlying neural entrainment is still not well-studied. Here, we designed a role-controlled cooperative task with dual EEG recording to explore how differently two brains interact when mothers and children hold different roles. When children were actors and mothers were observers, mother-child interbrain synchrony emerged primarily within the theta oscillations and the frontal lobe, which highly correlated with children's attachment to their mothers (self-reported by mothers). When their roles were reversed, this synchrony was shifted to the alpha oscillations and the central area and associated with mothers' perception of their relationship with their children. The results suggested an observer-actor neural alignment within the actor's oscillations, which was related to the actor-toward-observer emotional bonding. Our findings contribute to the understanding of how interbrain synchrony is established and dynamically changed during mother-child reciprocal interaction.

The association of maternal-infant interactive behavior, dyadic frontal alpha asymmetry, and maternal anxiety in a smartphone-adapted still face paradigm.

Mother-infant interactions form a strong basis for emotion regulation development in infants. These interactions can be affected by various factors, including maternal postnatal anxiety. Electroencephalography (EEG) hyperscanning allows for simultaneous assessment of mother-infant brain-to-behavior association during stressful events, such as the still-face paradigm (SFP). This study aimed at investigating dyadic interactive behavior and brain-to-behavior association across SFP and identifying neural correlates of mother-infant interactions in the context of maternal postnatal anxiety. We measured frontal alpha asymmetry (FAA), a physiological correlate of emotion regulation and a potential marker of risk for psychopathology. To emulate real-life interactions, EEG and behavioral data were collected from 38 mother-infant dyads during a smartphone-adapted dual-SFP. Although the behavioral data showed a clear still-face effect for the smartphone-adapted SFP, this was not reflected in the infant or maternal FAA. Brain-to-behavior data showed higher infant negative affect being associated with more infant leftward FAA during the still-face episodes. Finally, mothers with higher postnatal anxiety showed more right FAA during the first still-face episode, suggesting negative affectivity and a need to withdraw from the situation. Our results form a baseline for further research assessing the effects of maternal postnatal anxiety on infants' FAA and dyadic interactive behavior.

Mindfulness meditation enhances interbrain synchrony of adolescents when experiencing different emotions simultaneously.

Mindfulness is considered to benefit social behavior and interpersonal communication. However, the underlying neural mechanism has not been fully examined. This study aimed to explore how mindfulness practice affected the interbrain synchrony within adolescent peer dyads when sharing emotional experience together by using the electroencephalograph hyperscanning approach. Thirty adolescent dyads were randomly assigned to a mindfulness group or a non-mindfulness group. Mindfulness group performed a 20-min mindfulness exercise. Non-mindfulness group were instructed to rest. Simultaneously, electroencephalograph was recorded when they completed a picture-processing task. Phase-locking-value in the gamma band was used to calculate adolescent dyads' brain-to-brain synchrony. Results showed that greater interbrain synchrony in the frontal region was observed when viewing different emotional stimuli together after the mindfulness than before the mindfulness in the mindfulness group. However, there was no significant difference in the interbrain synchrony in the non-mindfulness group. Moreover, greater interbrain synchrony was observed in the mindfulness group than in the non-mindfulness group after mindfulness or rest in the frontal region. However, there was no significant difference between the mindfulness and non-mindfulness group before mindfulness or rest. The findings are discussed in light of the broader theoretical questions of how mindfulness may promote interpersonal functioning from a psychophysiological perspective.

Parental involvement affects parent-adolescents brain-to-brain synchrony when experiencing different emotions together: An EEG-based hyperscanning study.

Parental involvement (PI) is a broad and multifaceted construct, which refers to the parental demonstration of interest in their child, caring, and warmth (Davis et al., 2021). Parental involvement affects parent-adolescent's relationship and communication. However, there was little research to examine the underlying neural mechanism. The present study aimed to explore how parental involvement is associated with the brain-to-brain synchronous activation between parent-adolescent dyads when sharing emotional experience together by using the electroencephalograph (EEG) hyperscanning. EEG was recorded simultaneously in a sample of 26 parent-adolescent dyads (Mparents'age=43.312, SD=5.468; Madolescents' age=12.077, SD=1.412) when completing the picture processing task. Phase locking values (PLVs) in beta band and gamma band were used to compare the differences in the parent-adolescent dyads' induced brain-to-brain synchrony between the high parental involvement group (HPI) and the low parental involvement group (LPI). Results showed that greater beta brain-to-brain synchrony was observed in the HPIs than in the LPIs when experiencing positive emotions together in the central region. However, there was no significant difference between the HPIs and the LPIs in the negative and neutral condition. Moreover, greater gamma brain-to-brain synchrony was observed when viewing negative emotional stimuli together than viewing positive emotional stimuli together in the LPIs in the central region. However, there was no significant difference between different emotional conditions in the HPIs. Findings of the present study provide neuroscientific evidence that parental involvement may strengthen parent-adolescent's emotional interaction and communication.

The role of mindfulness on theta inter-brain synchrony during cooperation feedback processing: An EEG-based hyperscanning study

Mindfulness appears to improve empathy and understanding in relationships, which are necessary for successful cooperation. However, the impact of mindfulness on cooperation has not been fully studied. This study used hyperscanning technique to examine the effect of mindfulness on the inter-brain synchrony of interacting individuals during the cooperative tasks. Forty-one dyads were randomly assigned to a mindfulness group or a non-mindfulness group. Dyads of the mindfulness group performed a short mindfulness exercise following a 15-minute mindfulness audio guidance. Dyads of the non-mindfulness group were instructed to rest quietly with their eyes closed. Then, simultaneously and continuously EEG was recorded from all dyads when they completed a computer-based cooperative game task. Reaction times (RTs) and success rates were used to indicate the behavioral performance, and phase locking value (PLV) was used to indicate the inter-brain synchrony. The results showed that (1) Greater theta inter-brain synchrony during the cooperative computer game tasks was observed in the mindfulness group than in the non-mindfulness group; (2) Greater theta inter-brain synchrony was observed in the successful cooperation conditions as compared to those in the failure cooperation conditions; (3) Greater theta inter-brain synchrony was observed at the frontal region as compared to those at the parietal-occipital region in the successful cooperation condition. The results expand the neural basis of the effects of mindfulness on cooperation feedback processing. (AU)

Dynamics in interbrain synchronization while playing a piano duet.

Humans interact with each other through actions that are implemented by sensory and motor processes. To investigate the role of interbrain synchronization emerging during interpersonal action coordination, electroencephalography data from 13 pairs of pianists were recorded simultaneously while they performed a duet together. The study aimed to investigate whether interbrain phase couplings can be reduced to similar bottom-up driven processes during synchronous play, or rather represent cognitive top-down control required during periods of higher coordination demands. To induce such periods, one of the musicians acted as a confederate who deliberately desynchronized the play. As intended, on the behavioral level, the perturbation caused a breakdown in the synchronization of the musicians' play and in its stability across trials. On the brain level, interbrain synchrony, as measured by the interbrain phase coherence (IPC), increased in the delta and theta frequency bands during perturbation as compared to non-perturbed trials. Interestingly, this increase in IPC in the delta band was accompanied by the shift of the phase difference angle from in-phase toward anti-phase synchrony. In conclusion, the current study demonstrates that interbrain synchronization is based on the interpersonal temporal alignment of different brain mechanisms and is not simply reducible to similar sensory or motor responses.

Age differences in interbrain synchronization during peer cooperation: an EEG hyperscanning study.

Healthy peer relationships could provide emotional and social support for adolescents experiencing dramatic physical and environmental changes. Examining age differences in cognitive neural processing during peer interaction provides insight into adolescent interpersonal contact and "social brain" development. The present study compared the age differences between adolescents and adults by examining the behavior and interbrain synchronization of pairs in a cooperative computer game task. 32 pairs of adolescents and 31 pairs of adults were recruited as participants. The reaction times and interbrain synchronization of the participants were measured. The results revealed that interbrain synchronization activation following the onset of the "ready signal" was primarily detected in low-frequency bands such as delta and theta. Adolescent pairs' interbrain synchronization activations were significantly higher than those of adult pairs in the anterior and central brain regions, such as the frontal, frontal-central, and parietal lobes. Correlation analysis indicated a positive correlation between occipital region interbrain synchronization and behavioral performance. The findings provide behavioral and neurophysiological evidence for the characteristics of adolescent interpersonal cognitive processing and point to the significance of low-frequency interbrain synchronization in interpersonal coordination.

The role of mindfulness on theta inter-brain synchrony during cooperation feedback processing: An EEG-based hyperscanning study.

Mindfulness appears to improve empathy and understanding in relationships, which are necessary for successful cooperation. However, the impact of mindfulness on cooperation has not been fully studied. This study used hyperscanning technique to examine the effect of mindfulness on the inter-brain synchrony of interacting individuals during the cooperative tasks. Forty-one dyads were randomly assigned to a mindfulness group or a non-mindfulness group. Dyads of the mindfulness group performed a short mindfulness exercise following a 15-minute mindfulness audio guidance. Dyads of the non-mindfulness group were instructed to rest quietly with their eyes closed. Then, simultaneously and continuously EEG was recorded from all dyads when they completed a computer-based cooperative game task. Reaction times (RTs) and success rates were used to indicate the behavioral performance, and phase locking value (PLV) was used to indicate the inter-brain synchrony. The results showed that (1) Greater theta inter-brain synchrony during the cooperative computer game tasks was observed in the mindfulness group than in the non-mindfulness group; (2) Greater theta inter-brain synchrony was observed in the successful cooperation conditions as compared to those in the failure cooperation conditions; (3) Greater theta inter-brain synchrony was observed at the frontal region as compared to those at the parietal-occipital region in the successful cooperation condition. The results expand the neural basis of the effects of mindfulness on cooperation feedback processing.

Intra- and interbrain synchrony and hyperbrain network dynamics of a guitarist quartet and its audience during a concert.

Playing music in a concert represents a multilevel interaction between musicians and the audience, where interbrain synchronization might play an essential role. Here, we simultaneously recorded electroencephalographs (EEGs) from the brains of eight people during a concert: a quartet of professional guitarists and four participants in the audience. Using phase synchronization analyses between EEG signals within and between brains, we constructed hyperbrain networks, comprising synchronized brain activity across the eight brains, and analyzed them using a graph-theoretical approach. We found that strengths within and between brains in the delta band were higher in the quartet than in the public. Within-brain strengths were higher and between-brain strengths were lower in the music than in the applause condition, both particularly in the quartet group. These changes in coupling strength were accompanied by corresponding changes in the hyperbrain network topology, which were also frequency-specific. Moreover, the network topology and the dynamical structure of guitar sounds showed specific guitar-brain, guitar-guitar, and brain-brain directional associations, indicating multilevel dynamics with upward and downward causation. Finally, the hyperbrain networks exhibit modular structures that were more stable during music performance than during applause. Our findings illustrate complex hyperbrain network interactions in a quartet and its audience during a concert.

A two for one special: EEG hyperscanning using a single-person EEG recording setup.

EEG hyperscanning refers to recording electroencephalographic (EEG) data from multiple participants simultaneously. Many hyperscanning experimental designs seek to mimic naturalistic behavior, relying on unpredictable participant-generated stimuli. The majority of this research has focused on neural oscillatory activity that is quantified over hundreds of milliseconds or more. This contrasts with traditional event-related potential (ERP) research in which analysis focuses on transient responses, often only tens of milliseconds in duration. Deriving ERPs requires precise time-locking between stimuli and EEG recordings, and thus typically relies on pre-set stimuli that are presented to participants by a system that controls stimulus timing and synchronization with an EEG system. EEG hyperscanning methods typically use separate EEG amplifiers for each participant, increasing cost and complexity - including challenges in synchronizing data between systems. Here, we describe a method that allows for simultaneous acquisition of EEG data from a pair of participants engaged in conversation, using a single EEG system with simultaneous audio data collection that is synchronized with the EEG recording. This allows for the post-hoc insertion of trigger codes so that it is possible to analyze ERPs time-locked to specific events. We further demonstrate methods for deriving ERPs elicited by another person's spontaneous speech, using this setup.•EEG hyperscanning method using a single EEG amplifier•EEG hyperscanning method allowing simultaneous recording of audio data directly into the EEG data file for perfect synchronization•EEG method for naturalistic language and human interaction studies that allows the study of event-related potentials time-locked to spontaneous speech.

Relations between family cohesion and adolescent-parent's neural synchrony in response to emotional stimulations.

BACKGROUND: The interaction between parent and adolescent is more challenging than in other age periods. Family cohesion seriously impacts parent-adolescent emotional interactions. However, the underlying neural mechanism has not been fully examined. This study examined the differences in the neural synchrony in response to emotional film clips between high and low family cohesion adolescent-parent dyads by using the electroencephalograph (EEG) hyperscanning. RESULTS: Simultaneously electroencephalograph (EEG) was recorded while 15 low family cohesion parent-adolescent dyads (LFCs)and 14 high family cohesion parent-adolescent dyads (HFCs)received different emotional induction when viewing film clips. Interbrain phase-locking-value (PLV) in gamma band was used to calculate parent-adolescent dyads' interbrain synchrony. Results showed that higher gamma interbrain synchrony was observed in the HFCs than the LFCs in the positive conditions. However, there was no significant difference between the HFCs and LFCs in other conditions. Also, the HFCs had significantly higher gamma interbrain synchrony in the positive conditions than in the negative conditions. CONCLUSION: Interbrain synchrony may represent an underlying neural mechanism of the parent-adolescent emotional bonding, which is the core of family cohesion.

Adolescent social anxiety undermines adolescent-parent interbrain synchrony during emotional processing: A hyperscanning study.

Social anxiety severely impacts adolescents' social interactions with others; however, the underlying neural mechanism has not been revealed. This study examined how adolescent's social anxiety level influences the interbrain synchrony within adolescent-parent dyads during emotional processing by using electroencephalograph (EEG) hyperscanning. A sample of 25 adolescent-parent dyads completed the picture processing task. Adolescents' ages ranged from 10 to 14 years old. The results showed that (1) at parietal areas, greater gamma interbrain synchrony was observed in the high social anxiety adolescent-parent dyads (HSAs) than the low social anxiety adolescent-parent dyads (LSAs) in the positive conditions. However, greater gamma interbrain synchrony of the picture processing task was observed in the LSAs than the HSAs in the negative conditions. (2) Compared with the neutral condition, LSAs induced greater interbrain synchronization in the negative condition than in the neutral condition at central and parietal areas. However, HSAs induced greater interbrain synchronization in the positive condition than in the negative condition at parietal areas. (3) HSAs induced greater interbrain synchronization at parietal areas than in the central areas in positive conditions. The results provide neurological evidence that the way parent and adolescent process different emotions in the same emotional episode could be affected by the adolescent's anxiety level.

Adolescent social anxiety undermines adolescent-parent interbrain synchrony during emotional processing: A hyperscanning study

Social anxiety severely impacts adolescents’ social interactions with others; however, the underlying neural mechanism has not been revealed. This study examined how adolescent's social anxiety level influences the interbrain synchrony within adolescent-parent dyads during emotional processing by using electroencephalograph (EEG) hyperscanning. A sample of 25 adolescent-parent dyads completed the picture processing task. Adolescents’ ages ranged from 10 to 14 years old. The results showed that (1) at parietal areas, greater gamma interbrain synchrony was observed in the high social anxiety adolescent-parent dyads (HSAs) than the low social anxiety adolescent-parent dyads (LSAs) in the positive conditions. However, greater gamma interbrain synchrony of the picture processing task was observed in the LSAs than the HSAs in the negative conditions. (2) Compared with the neutral condition, LSAs induced greater interbrain synchronization in the negative condition than in the neutral condition at central and parietal areas. However, HSAs induced greater interbrain synchronization in the positive condition than in the negative condition at parietal areas. (3) HSAs induced greater interbrain synchronization at parietal areas than in the central areas in positive conditions. The results provide neurological evidence that the way parent and adolescent process different emotions in the same emotional episode could be affected by the adolescent's anxiety level. (AU)

EEG Hyperscanning and Qualitative Analysis of Moments of Interest in Music Therapy for Stroke Rehabilitation-A Feasibility Study.

Interdisciplinary research into the underlying neural processes of music therapy (MT) and subjective experiences of patients and therapists are largely lacking. The aim of the current study was to assess the feasibility of newly developed procedures (including electroencephalography/electrocardiography hyperscanning, synchronous audio-video monitoring, and qualitative interviews) to study the personal experiences and neuronal dynamics of moments of interest during MT with stroke survivors. The feasibility of our mobile setup and procedures as well as their clinical implementation in a rehabilitation centre and an acute hospital ward were tested with four phase C patients. Protocols and interviews were used for the documentation and analysis of the feasibility. Recruiting patients for MT sessions was feasible, although data collection on three consecutive weeks was not always possible due to organisational constraints, especially in the hospital with acute ward routines. Research procedures were successfully implemented, and according to interviews, none of the patients reported any burden, tiredness, or increased stress due to the research procedures, which lasted approx. 3 h (ranging from 135 min to 209 min) for each patient. Implementing the research procedures in a rehabilitation unit with stroke patients was feasible, and only small adaptations were made for further research.

Audience Interbrain Synchrony During Live Music Is Shaped by Both the Number of People Sharing Pleasure and the Strength of This Pleasure.

The study of interbrain coupling in a group of people attending a concert together is a favorable framework to estimate group emotions and more precisely emotional connection between people sharing situations in the same environment. It offers the advantage of studying interactions at the group level. By recording the cerebral activity of people from an audience during a concert using electroencephalography, we previously demonstrated that the higher the emotions and the physically closer the people were, the more the interbrain synchrony (IBS) was enhanced. To further investigate the parameters that shaped inter-brain synchronization in this context, we now focus on the emotional dynamics of the group as a whole by identifying specific moments in the concert that evoked strong or weak emotions, as well as strong or weak emotional cohesion between individuals. We demonstrated that audience interbrain synchrony is mainly associated with experiencing high musical pleasure and that the group emotional cohesion can enhance IBS, but alone is not the major parameter that shapes it in this context.

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.

Inter-brain synchronization is weakened by the introduction of external punishment.

Punishment is a popular institution to enforce social norms in human society. However, how the punishment institution impacts the inter-brain neural signatures of two-person social interactions is still an open question. By performing electroencephalography recording of brain activity in two interacting parties as they simultaneously played both the revised repeated ultimatum game (rrUG) and the revised repeated dictator game (rrDG), this study focused on exploring how the introduction of external punishment influences inter-brain synchronization between the two parties. The data showed a significant negative effect of external punishment on inter-brain synchronization, with greater inter-brain synchronization observed in the rrDG than in the rrUG. We proposed a possible mechanism underlying this result. In the rrDG, the similar moral motivation of both proposers and responders results in inter-brain synchronization between them. However, in the rrUG, the introduction of external punishment crowds out the intrinsic moral motivation of the proposers, thereby undermining the inter-brain synchronization. Moreover, we found a significant positive correlation between the rejection rate from responders for disadvantageous inequal offer and inter-brain synchronization in the rrDG. These findings contribute to understanding the negative effect of punishment institution and shed light on the inter-brain mechanism underlying social interaction.

Interbrain emotional connection during music performances is driven by physical proximity and individual traits.

How musical emotions and the pleasure derived from music, regardless of the musical valence, can be shared between individuals is a fascinating question, and investigating it can shed light on the function of musical reward. We carried out our investigations in a natural setting during an international competition for orchestra conductors. Participants (n = 15) used a dedicated smartphone app to report their subjective emotional experiences in real time while we recorded their cerebral activity using electroencephalography and their electrodermal activity. The overall behavioral real-time behavioral ratings suggest a possible social influence on the reported and felt pleasure. The physically closer the participants, the more similar their reported pleasure. By calculating the interindividual cerebral coherence (n = 21 pairs), we showed that when people simultaneously reported either high or low pleasure, their cerebral activities were closer than for simultaneous neutral pleasure reports. Participants' skin conductance levels were also more coupled when reporting higher emotional degrees simultaneously. More importantly, the participants who were physically closer had higher cerebral coherence, but only when they simultaneously reported a high level of pleasure. We propose that emotional contagion and/or emotional resonance mechanisms could explain why a form of "emotional connecting force" arises between people during shared appraisal situations.