The Neural Mechanism Of Musical Rhythm On The Process Of Music Evoked Emotion

In music activities,human's evoked emotion is an important aspect of psychology,music psychology and cognitive neuroscience.Rhythm is an important factor affecting musical emotion.Fast music mainly arouses positive and strong emotional experience,while slow music mainly arouses negative and calm emotional experience.However,why do different rhythm tempi generate such different emotional effects? What is the underlying neurological mechanism? Apart from rhythm tempi,are there any other subattributes of rhythm that affect music evoked emotion? To explore these questions,we can not only clarify the internal relationship between music rhythm and emotional processing,but also promote the development of brain neuroplasticity in the field of music emotion,and provide strong evidence for the psychological health function of music.Rhythm is a modality that the general things are carried out alternately and orderly.In music,rhythm refers to the organization form and movement mode formed by beats' length and intensity.It arouses audience's sense of tempi and patterns,which corresponds to the rhythm tempo of temporal dimension and pattern of spatial dimension respectively.Previous studies of music rhythm's effects on emotional processing mainly focused on the influence of tempo on individuals' music evoked emotion and psychophysiological activities.However,there is still a lack of research combining subjective emotional experience and objective emotional neural mechanism activities,and the lack of researching patterns' affecting on music emotional processing.Patterns is a typical,recurring and typical rhythm unit in music,which presents the beats of a certain length of times and number of cycles and has relatively independent semantic information,and has internal beat and distinct musical characteristic.By comparing the EEG activity of individual perceiving 2/4 pattern and 3/4 pattern,it was found that 3/4 pattern induced a wider range of sensormotor cortex and fronto-parietal joint cortex than 2/4 pattern,reflecting the effects of rhythmic pattern in individuals' musical processing.In addition,as a typical artistic form of emotion arousal,music-evoked emotion has a close relationship not only with the acoustic properties of music,but also with the audiences' age,gender,music training experience and social cognition,in which social cognition includes individuals' social status,personality traits,emotional feelings,social cultural background and so on.To explore the neural mechanism of music rhythm affecting emotional processing,we should not only realize the rational operation of rhythm variables,but also effectively control the relevant additional variables.At the theoretical level,it can be helpful to clarify the relationship between rhythm and music emotion.Practically,their relationship can provide operational guidance for the psychological health value of music emotion.Based on its acoustic characteristics and psychological effects,rhythm was defined operationally as periodic repetitive music attribute with the specific rhythm tempo and rhythm pattern.This study explored the musical effects of three tempi(fast-tempo,medium-tempo and slow-tempo)and four patterns(2/4 pattern,3/4 pattern,4/4 pattern,6/8 pattern)on the brain neurological activity of males and females' music emotional processing by passive listening paradigm in real music and rhythm only music,with a view to clarifying the neurological mechanism of music rhythm affecting emotional processing.Study 1: Investigation of music uses and music emotional characteristics.Part A of the study was to carry out a questionnaire survey on music use and music emotional characteristics.?Music Use Questionnaire? and ?Music Preference Survey?were used to investigate college students' music use purpose,music style preference,music appreciation scene preference,music emotional experience and music preference formation.Part B of the study compared the differences between non-musicians and musicians in their subjective experience of musical emotion and brain activity.Part C of the study compared the differences of individuals' subjective experience and brain image activity between pop,classical,national,jazz and rock music.It was found that music training experience and music style significantly affected listeners' music emotional processing.Therefore,in the follow-up study,non-musicians and music materials of unified style were selected to explore the influence of rhythm tempi and rhythm pattern on music emotions.Study 2: The influence of rhythm tempi on music evoked emotion.This part contained three experiments.In Experiment 1,music evoked emotion was induced by passive listening paradigm,and the effects of fast-tempo,medium-tempo and slow-tempo on emotional experience and brain activity of non-musicians were explored in twelve pieces of classical music.Experiment 2 explored the effects of three rhythm tempi on males and females' emotional experience and brain image activity.In Experiment 3,rhythm only music of above twelve songs were further produced,and tempi's effect on individual emotional processing was compared among fast-tempo,medium-tempo and slow-tempo music.Study 3: The influence of rhythm pattern on music emotional processing.This part contained three experiments.In Experiment 4,music emotion was induced by passive listening paradigm,and the effects of 2/4 pattern,3/4 pattern,4/4 pattern,6/8 pattern on the emotional experience and brain image activity of non-musicians were explored in one hundred pieces of pop music.Experiments 5 explored the effects of 2/4 pattern,3/4 pattern,4/4 pattern,6/8 pattern on males and females' emotional experience and brain image activity.In Experiment 6,rhythm only music of above one hundred songs were made to compare the effects of 2/4 pattern,3/4 pattern,4/4 pattern,6/8 pattern on individual emotional processing.Based on the above studies,three results were obtained:Study 1 showed a close relationship between musical emotion and its music use content,music training experience and music style.College students mainly used music because of its emotional purposes and experience pleasure and excitement.They preferred popular,rock,folk,jazz and classical music.Musicians and non-musicians showed no difference in emotional arousal and pleasure experience,but musicians showed stronger activation in the left inferior parietal lobule than non-musicians.As for the music style,differences were significant in arousal and pleasure between pop,rock,folk songs,jazz and classical music,among which rock music had the highest score of arousal and classical music had the highest pleasure.In functional magenetic resonance image(fMRI)results,only pop music showed activation of bilateral superior temporal gyrus and bilateral auxiliary motor areas,while the other four styles showed deactivation of different brain regions.Above results guided the follow-up study to choose the subjects with unified music training experience and the music of unified style.Study 2 showed that rhythm tempo had a significant impact on the listeners' emotional processing of music,and generated difference between males and females.In real music,rhythm tempi did not affect the individual's emotional pleasure experience,but significantly affected the individual's emotional arousal: fast-tempo music was scored the highest in emotion arousal dimension,medium-tempo music was scored the lowest.In fMRI result,medium-tempo music activated stronger bilateral superior temporal gyrus,bilateral precuneus and right posterior cingulate gyrus than slow-tempo music.In subjective evaluation of music evoked emotion,no difference was found in the processing of musical emotion between males and females.However in fMRI,females activated stronger bilateral superior inferior frontal gyrus,bilateral precuneus and left occipital visual association cortex under fast-slow conditions.In the rhythm only music,fast-tempo music significantly aroused greater pleasure and arousal than medium-tempo and slowtempo music,and induced stronger activation in bilateral superior temporal gyrus.Study 3 show that rhythm pattern has a significant impact on the listeners' musical emotional processing,and shows a different role between males and females.Among the four typical rhythmic patterns(2/4 pattern,3/4 pattern,4/4 pattern and 6/8 pattern),4/4 rhythmic patterns had significant emotional arousal effects,showed the highest scores of arousal and pleasure,and significantly activated bilateral superior temporal gyrus and supplementary motor cortex at the brain level.The difference of musical emotion between the males and females was significant in the 6/8 rhythm pattern.Females showed stronger activation of left frontal pole and right posterior central gyrus than males,including right inferior parietal lobule and right secondary somatosensory cortex.There were no significant differences in emotional evaluation and neurological activity among the four rhythmic stimuli.In conclusion,rhythm is an important music element in regulating music evoked emotion.It has an important impact on the subjective experience of musical evoked emotion and brain image processing by tempo and pattern.Females are more likely to be affected by rhythm changes than males in the processing of musical emotion.By comparing the rhythm only music of three tempi and four patterns,it can be speculated that the influence of tempi on music emotion is more prominent than that of rhythm pattern to a certain extent.Tempo is the core component of rhythm,which presents the changes of rhythm temporally.Fast-tempo music can evoke the strongest emotional experience and activate the superior temporal gyrus and precuneus related to auditory processing and emotional processing.The females' activation of the occipital lobe indicate that fast-tempo music can promote individual's emotional processing through visual imagination.Although medium-tempo music has the lowest degree of emotion arousal,it can still effectively arouse the brain related to auditory processing and emotional regulation.As a stimulation closest to human physiological rhythm,the characteristics of medium-tempo could activate listeners' acoustical process and emotional process without arousing their subjective emotional perception.Pattern is another important sub-attribute of rhythm,which is an important organizational feature of rhythm in spatial dimension.As subjects' most familiar pattern in daily life,4/4 pattern has the greatest advantage in arousing individual's musical emotion processing.6/8 pattern is more complex than the other three rhythm types,and females were found to engage stronger brain activation than males in 6/8 pattern music,which implied that different pattern could impose different emotional effectivities in males and females.The study defines rhythm operatively by breakthrough selection of its tempi and pattern,which provides an important theoretical basis for exploring the relationship between music rhythm and music evoked emotion,as well as guiding evidence for the clinical application of musical emotion.The research not only provides reliable empirical support for the subjects and the selection of music emotion-inducing materials,but also provides objective guarantee for describing the influence mechanism of music rhythm on emotional processing.In the future,the research will further enrich the sample of multilevel subjects and explore the interaction between different sub-attributes of rhythm,so as to promote the exploration of brain nervous mechanism of musical emotion and the popularization and application of clinical practice.