Naturalistic music and dance : Cortical phase synchrony in musicians and dancers

Expertise in music has been investigated for decades and the results have been applied not only in composition, performance and music education, but also in understanding brain plasticity in a larger context. Several studies have revealed a strong connection between auditory and motor processes and listening to and performing music, and music imagination. Recently, as a logical next step in music and movement, the cognitive and affective neuro-sciences have been directed towards expertise in dance. To understand the versatile and overlapping processes during artistic stimuli, such as music and dance, it is necessary to study them with continuous naturalistic stimuli. Thus, we used long excerpts from the contemporary dance piece Carmen presented with and without music to professional dancers, musicians, and laymen in an EEG laboratory. We were interested in the cortical phase synchrony within each participant group over several frequency bands during uni- and multimodal processing. Dancers had strengthened theta and gamma synchrony during music relative to silence and silent dance, whereas the presence of music decreased systematically the alpha and beta synchrony in musicians. Laymen were the only group of participants with significant results related to dance. Future studies are required to understand whether these results are related to some other factor (such as familiarity to the stimuli), or if our results reveal a new point of view to dance observation and expertise.Peer reviewe

EEG Analysis during Music Perception

This review presents the most interesting results of electroencephalographic studies on musical perception performed with different analysis techniques. In first place, concepts on intra-musical characteristics such as tonality, rhythm, dissonance or musical syntax, which have been object of further investigation, are introduced. Most of the studies found use listening musical extracts, sequences of notes or chords as an experimental situation, with the participants in a resting situation. There are few works with participants performing or imagining musical performance. The reviewed works have been divided into two groups: a) those that analyze the EEGs recorded in different cortical areas separately using frequency domain techniques: spectral power, phase or time domain EEG procedures such as potentials event related (ERP); b) those that investigate the interdependence between different EEG channels to evaluate the functional connectivity between different cortical areas through different statistical or synchronization indices. Most of the aspects studied in music-brain interaction are those related to musical emotions, syntax of different musical styles, musical expectation, differences between pleasant and unpleasant music and effects of musical familiarity and musical experience. Most of the works try to know the topographic maps of the brain centers, pathways and functions involved in these aspects

Dance on Cortex : ERPs and Phase Synchrony in Dancers and Musicians during a Contemporary Dance Piece

Music and dance have been important parts of the human experience for millennia. They have enabled interaction which has given rise to resilient communities and rich cultures. Neuroscience has studied music for decades. It has been found to activate both the cortical and deeper brain areas in a unique way. Neuroscience of dance, instead, is a young but quickly growing field. Studies of professional dancers and musicians have highlighted the importance of multimodal interaction and motor-related brain regions in cerebral processing of dance and music. Current direction of neuroscience is to study the brain in its natural environment. Therefore, simplified stimuli made for the laboratory conditions have been replaced by the stimuli of the real world, such as arts and social interaction. Despite these continuous stimuli have already been successfully studied with fMRI, methods to study cortical EEG under such stimuli are lacking. The purpose of my doctoral research is to develop and use two methods for studying the brain with EEG during the perception of dance and music. One of these methods is based on the event-related potentials (ERPs) to investigate the influence of fast changes of musical features in the brain in a short timescale. The other method utilizes changes in phase synchrony between two electrode channels when investigating cortical dynamics during observation of dance and music over a longer timescale. In my doctoral research, the developed methods are applied in studying differences in cortical dynamics of professional dancers, musicians and laymen. By both methods, differences in brain activity were found between the groups of experts and laymen when watching dance or listening to music. In addition, these methods detected changes in lower lever brain processes related to uni- and multimodal processing and acceleration of dance movement. By the ERP method, dancers were shown to have an enhanced auditory P50 response when compared to musicians and laymen which refers to dancers’ modulated processing of musical features in an early preattentive level. The method of phase synchrony revealed enhanced theta (4-8 Hz) synchrony in dancers when compared to two other groups when watching audio-visual dance. During music, dancers had enhanced theta and gamma (30-48 Hz) synchrony when compared to conditions without music. Both theta and gamma are associated with higher order processing related to multimodal integration, memory and emotions. In contrast, musicians had decreased alpha (8-13 Hz) and beta (13-30 Hz) synchrony when listening to music. These frequency bands are associated with movement preparation and execution. In addition, laymen were the only group which showed systematic changes in synchrony during dance when compared to the conditions without dance. These changes occurred on theta, alpha, beta and gamma bands. The processing of early changes within uni- and multimodal stimuli, and the accelerated movement of the body did not differ between dancers, musicians and laymen. In all groups, the auditory ERP responses were generally suppressed and sped up during multimodal presentation of music when compared to the unimodal stimulus. Also, the alpha synchrony was decreased in all groups during the parts of the choreography with accelerated large dance movement when compared to parts with nearly still presence. These changes were the strongest during the audio-visual stimulus with a real dancer. Also, during audio-visual dancing stick figure and silent dance some cortical regions showed decreased alpha synchrony for fast dance movement. Decreased alfa-synchrony is associated to motor processing and higher state of alertness in general. These results show that the methods developed in my doctoral research are suitable in analysing continuous EEG of naturalistic artistic stimuli, and in detecting changes in cortical processing of dancers and musicians during such stimuli. The results of the study suggest that dancers have modulated cortical processing related to multimodal interaction, memory and/or emotions whereas musicians have a special motor-related processing when listening to music. The methods developed in my doctoral research can be used when watching a live performance to study further dance and musical expertise. These methods can be directly applied during music production and light dancing. Several neurological and psychiatric disorders are associated with abnormalities in oscillatory activity, especially in cross-frequency coupling. Therefore, development of the phase synchrony method to that direction is essential. Together this array of methods could be applied in estimating the efficiency and developing further expressive therapies, such as dance-movement therapy, and in alleviating symptoms as a part of holistic treatment plan for conditions such as Parkinson’s disease, dementia, autism, and pain and mood disorders.  Musiikki ja tanssi ovat tuottaneet kallisarvoisia kokemuksia ihmisille jo vuosituhansien ajan. Niiden kautta syntyneen vuorovaikutuksen avulla on muodostunut elinvoimaisia yhteisöjä ja rikkaita kulttuureja. Musiikkia on tutkittu neurotieteen näkökulmasta jo vuosikymmeniä. Sen on osoitettu aktivoivan sekä aivokuoren alueita että syvempiä aivojen rakenteita ainutlaatuisella tavalla. Tanssin neurotiede sen sijaan on nuori, mutta nopeasti kasvava tieteenala. Ammattitanssijoilla ja -muusikoilla tehdyt tutkimukset osoittavat eri aistien vuorovaikutteisen informaation ja liikkeen aivoalueiden tärkeyden tanssin ja musiikin herättämissä aivoprosesseissa. Tällä hetkellä neurotiede suuntautuu tutkimaan aivoja niiden luonnollisessa ympäristössä. Sen vuoksi laboratorio-olosuhteisiin suunnitellut yksinkertaiset ärsykkeet on korvattu todellisen maailman ärsykkeillä, kuten taiteella ja sosiaalisella vuorovaikutuksella. Vaikka tällaisia jatkuvia ärsykkeitä on jo menestyksellisesti tutkittu funktionaalisella aivokuvantamisella (fMRI), menetelmät näiden ärsykkeiden tutkimiseen aivosähkökäyrällä (EEG) puuttuvat. Väitöskirjatyöni tarkoituksena on kehittää kaksi menetelmää ja käyttää niitä aivojen tutkimiseen EEG-tekniikalla tanssin katselun ja musiikin kuuntelun aikana. Toinen menetelmä perustuu tapahtumasidonnaisiin aivovasteisiin (ERP) tutkittaessa musiikkipiirteiden nopeiden muutosten vaikutusta aivoissa lyhyellä aikajänteellä. Toinen menetelmä taas perustuu kahden elektrodikanavan välille syntyvään vaihesynkroniaan tutkittaessa aivokuoren toiminnan muutoksia tanssi- ja musiikkihavainnon aikana pidemmällä aikajänteellä. Väitöskirjatyössäni kehitettyjä menetelmiä käytetään ammattitanssijoiden, -muusikoiden ja kontrolliryhmän aivokuoren toiminnan erojen tutkimiseen. Sekä ERP- että vaihesynkroniamenetelmän avulla havaittiin eroja ammattilaisryhmien ja kontrolliryhmän välillä tanssin katselun ja musiikkin kuuntelun aikana. Lisäksi näillä menetelmillä havaittiin muutoksia matalamman tason aivoprosesseissa, jotka liittyivät yksi- ja moniaistillisen ärsykkeen käsittelyyn sekä kehon liikkeen kiihtyvyyden muutoksiin. ERP-menetelmän avulla tanssijoilla voitiin osoittaa olevan suurempi P50-kuulovaste verrattuna muusikoihin ja kontrolliryhmään, mikä viittaa musiikkipiirteiden kehittyneeseen käsittelyyn aikaisella esi-tietoisella tasolla. Vaihesynkronia-menetelmän avulla tanssijoilla havaittiin voimistunut theta-synkronia (4-8 Hz) verrattuna kahteen muuhun ryhmään audiovisuaalista tanssia katsottaessa. Tanssijoilla todettiin musiikin kuuntelun aikana voimistunut theta- ja gamma-synkronia (30-48 Hz) verrattuna ärsykkeisiin ilman musiikkia. Sekä theta- että gamma-synkronia liitetään korkeamman tason aivoprosesseihin, kuten moniaistillisen ärsykkeen yhdistämiseen, muistiin ja tunteisiin. Muusikoilla sen sijaan oli heikentynyt alfa- (8-13 Hz) ja beta-synkronia (13-30 Hz) musiikin kuuntelun aikana. Nämä taajuuskaistojen synkronian heikkenemiset yhdistetään liikkeeseen valmistautumiseen ja sen suorittamiseen. Kontrolliryhmä oli ainoa ryhmä, jolla löytyi systemaattisia synkronian muutoksia tanssin katsomisen aikana verrattuna ärsykkeisiin ilman tanssia. Nämä muutokset esiintyivät theta, alfa, beta ja gamma-kaistoilla. Tanssiin ja musiikkiin liittyvän nopeasti muuttuvan yksi- ja moniaistillisen ärsykkeen ja kehon kiihtyvän liikkeen käsittelyssä ei havaittu eroja tanssijoiden, muusikoiden ja kontrolliryhmän välillä. Kaikissa ryhmissä ERP-kuulovasteet heikkenivät ja ilmaantuivat nopeammin moniaistillisesti esitetyn musiikin aikana, kun sitä verrattiin vain ääniärsykkeenä esitettyyn musiikkiin. Alfa-synkronia laski kaikissa ryhmissä koreografian kiihtyvää suurta liikettä sisältävien osioiden aikana, kun sitä verrattiin lähes paikallaanolevan läsnäolon osioihin. Nämä muutokset olivat voimakkaimpia tanssijan esittämän audiovisuaalisen ärsykkeen aikana. Samantyyppisiä muutoksia havaittiin myös äänettömän tanssin ja audio-visuaalisen tikku-ukon ärsykkeiden aikana. Heikentynyt alfa-synkronia viittaa liikkeen käsittelyyn sekä yleisen vireystason nousuun. Nämä tulokset osoittavat, että väitöskirjatyössäni kehitetyt menetelmät soveltuvat luonnollisen taiteellisen ärsykkeen synnyttämän jatkuvan EEG-aineiston analysointiin sekä aivokuoren toiminnan muutoksien havainnointiin ja tutkimiseen tanssijoilla ja muusikoilla kyseisen ärsykkeen aikana. Tutkimuksen tulokset viittaavat siihen, että tanssijoiden aivokuoren, erityisesti moniaistilliseen tanssin katseluun, muistiin ja/tai tunteisiin liittyvät toiminnat eroavat tanssijoilla muusikoista ja maallikoista. Muusikoilla sen sijaan musiikin kuuntelu herättää erityisiä liikkeeseen liittyviä aivokuoren prosesseja. Tässä tutkimuksessa kehitettyjä menetelmiä voidaan käyttää live-esityksen katselun aikana tanssijoiden ja muusikoiden aivokuoren eroavaisuuksien syvempään ymmärtämiseen. Näitä menetelmiä voi suoraan soveltaa musiikin soittamisen ja kevyen tanssimisen aikana. Aivojen oskillaation epätavalliset muutokset liittyvät moniin neurologisiin ja psykiatrisiin häiriöihin. Nämä muutokset esiintyvät erityisesti eri tajuuskaistojen välisessä synkroniassa. Sen takia on olennaista kehittää vaihesynkronia-menetelmää taajuuskaistojen välisen synkronian suuntaan. Tätä uutta metodologista kokonaisuutta voitaisiin soveltaa terapian vaikuttavuuden arvioinnissa ja ilmaisullisten terapioiden, kuten tanssi- ja liiketerapian, kehittämisessä pidemmälle esimerkiksi Parkinsonin taudin, muistisairauksien, autismin, ja kipu- ja mielialahäiriöiden oireiden lievittämiseksi ja jopa parantamiseksi osana kokonaisvaltaista hoito-ohjelmaa

Brain-to-brain communication during musical improvisation: a performance case study [version 4; peer review: 1 approved, 2 approved with reservations]

Understanding and predicting others' actions in ecological settings is an important research goal in social neuroscience. Here, we deployed a mobile brain-body imaging (MoBI) methodology to analyze inter-brain communication between professional musicians during a live jazz performance. Specifically, bispectral analysis was conducted to assess the synchronization of scalp electroencephalographic (EEG) signals from three expert musicians during a three-part 45 minute jazz performance, during which a new musician joined every five minutes. The bispectrum was estimated for all musician dyads, electrode combinations, and five frequency bands. The results showed higher bispectrum in the beta and gamma frequency bands (13-50 Hz) when more musicians performed together, and when they played a musical phrase synchronously. Positive bispectrum amplitude changes were found approximately three seconds prior to the identified synchronized performance events suggesting preparatory cortical activity predictive of concerted behavioral action. Moreover, a higher amount of synchronized EEG activity, across electrode regions, was observed as more musicians performed, with inter-brain synchronization between the temporal, parietal, and occipital regions the most frequent. Increased synchrony between the musicians' brain activity reflects shared multi-sensory processing and movement intention in a musical improvisation task

Cortico-muscular coherence in sensorimotor synchronisation

This thesis sets out to investigate the neuro-muscular control mechanisms underlying the ubiquitous phenomenon of sensorimotor synchronisation (SMS). SMS is the coordination of movement to external rhythms, and is commonly observed in everyday life. A large body of research addresses the processes underlying SMS at the levels of behaviour and brain. Comparatively, little is known about the coupling between neural and behavioural processes, i.e. neuro-muscular processes. Here, the neuro-muscular processes underlying SMS were investigated in the form of cortico-muscular coherence measured based on Electroencephalography (EEG) and Electromyography (EMG) recorded in human healthy participants. These neuro-muscular processes were investigated at three levels of engagement: passive listening and observation of rhythms in the environment, imagined SMS, and executed SMS, which resulted in the testing of three hypotheses: (i) Rhythms in the environment, such as music, spontaneously modulate cortico-muscular coupling, (ii) Movement intention modulates cortico-muscular coupling, and (iii) Cortico-muscular coupling is dynamically modulated during SMS time-locked to the stimulus rhythm. These three hypotheses were tested through two studies that used Electroencephalography (EEG) and Electromyography (EMG) recordings to measure Cortico-muscular coherence (CMC). First, CMC was tested during passive music listening, to test whether temporal and spectral properties of music stimuli known to induce groove, i.e., the subjective experience of wanting to move, can spontaneously modulate the overall strength of the communication between the brain and the muscles. Second, imagined and executed movement synchronisation was used to investigate the role of movement intention and dynamics on CMC. The two studies indicate that both top-down, and somatosensory and/or proprioceptive processes modulate CMC during SMS tasks. Although CMC dynamics might be linked to movement dynamics, no direct correlation between movement performance and CMC was found. Furthermore, purely passive auditory or visual rhythmic stimulation did not affect CMC. Together, these findings thus indicate that movement intention and active engagement with rhythms in the environment might be critical in modulating CMC. Further investigations of the mechanisms and function of CMC are necessary, as they could have important implications for clinical and elderly populations, as well as athletes, where optimisation of motor control is necessary to compensate for impaired movement or to achieve elite performance

The neuroscience of musical creativity using complexity tools

This project is heavily experimental and draws on a wide variety of disciplines from musicology and music psychology to cognitive neuroscience and (neuro)philosophy. The objective is to explore and characterise brain activity during the process of creativity and corroborating this with self-assessments from participants and external assessments from professional “judges”. This three-way experimental design bypasses the semantically difficult task of defining and assessing creativity by asking both participants and judges to rate ‘How creative did you think that was?’. Characterising creativity is pertinent to complexity as it is an opportunity to comprehensively investigate a neural and cognitive system from multiple experimental and analytical facets. This thesis explores the anatomical and functional system underlying the creative cognitive state by analysing the concurrent time series recorded from the brain and furthermore, investigates a model in the stages of creativity using a behavioural experiment, in more detail than hitherto done in this domain. Experimentally, the investigation is done in the domain of music and the time series is the recorded Electroencephalogram (EEG) of a pianist’s whilst performing the two creative musical tasks of ‘Interpretation’ and ‘Improvisation’ manipulations of musical extracts. An initial pilot study consisted of 5 participants being shown 30 musical extracts spanning the Classical soundworld across different rhythms, keys and tonalities. The study was then refined to only 20 extracts and modified to include 10 Jazz extracts and 8 participants from a roughly equal spread of Classical and Jazz backgrounds and gender. 5 external assessors had a roughly even spread of expertise in Jazz and Classical music. Source localisation was performed on the experimental EEG data collected using a software called sLORETA that allows a linear inverse mapping of the electrical activity recorded at the scalp surface onto deeper cortical structures as the source of the recorded activity. Broadman Area (BA) 37 which has previously been linked to semantic processing, was robustly related to participants from a Classical background and BA 7 which has previously been linked to altered states of consciousness such as hypnagogia and sleep, was robustly related to participants from a Jazz background whilst Improvising. Analyses exploring the spread, agreement and biases of ratings across the different judges and self-ratings revealed a judge and participant inter-rater reliability at participant level. There was also an equal agreement between judges when rating the different genres Jazz or Classical, across the different tasks of ‘Improvisation’ and ‘Interpretation’, increasing confidence in inter-genre rating reliability for further analyses on the EEG of the extracts themselves. Furthermore, based on the ratings alone, it was possible to partition participants into either Jazz or Classical, which agreed with phenomenological interview information taken from the participants themselves. With the added conditions of extracts that were deemed creative by objective judge assessment, source localisation analyses pinpointed BA 32 as a robust indicator of Creativity within the participants’ brain. It is an area that is particularly well connected and allows an integration of motoric and emotional communication with a maintenance of executive control. Network analysis was performed using the PLV index (Phase Locking Value) between the 64 electrodes, as the strength of the links in an adjacency matrix of a complex network. This revealed the brain network is significantly more efficient and more strongly synchronised and clustered when participants’ are playing Classical extracts compared to Jazz extracts, in the fronto-central region with a clear right hemispheric lateralization. A behavioural study explored the role of distraction in the ‘Incubation’ period for both interpretation and improvisation using a 2-back number exercise occupying working memory, as the distractor. Analysis shows that a distractor has no significant effect on ‘Improvisation’ but significantly impairs ‘Interpretation’ based on the self-assessments by the participants.Open Acces

Music in the brain

Music is ubiquitous across human cultures — as a source of affective and pleasurable experience, moving us both physically and emotionally — and learning to play music shapes both brain structure and brain function. Music processing in the brain — namely, the perception of melody, harmony and rhythm — has traditionally been studied as an auditory phenomenon using passive listening paradigms. However, when listening to music, we actively generate predictions about what is likely to happen next. This enactive aspect has led to a more comprehensive understanding of music processing involving brain structures implicated in action, emotion and learning. Here we review the cognitive neuroscience literature of music perception. We show that music perception, action, emotion and learning all rest on the human brain’s fundamental capacity for prediction — as formulated by the predictive coding of music model. This Review elucidates how this formulation of music perception and expertise in individuals can be extended to account for the dynamics and underlying brain mechanisms of collective music making. This in turn has important implications for human creativity as evinced by music improvisation. These recent advances shed new light on what makes music meaningful from a neuroscientific perspective