The Study Of The Neural Basis And Music Training Effects Of Music Meaning Processing In Congenital Singers

Music is an important communicative system for human beings,and deciphering musical meaning is a primary motivation for music listeners.Although musical meaning can be conveyed through multiple cues,extra-musical meaning and intramusical meaning are regarded as two main classes of musical meaning.Previous studies have proposed that extra-musical meaning emerges from the interpretation of musical sign qualities with reference to the extra-musical world,while intra-musical meaning emerges from one musical element(or group of elements)pointing structurally to another musical element(or group of elements).In this scenario,iconic musical meaning and indexical musical meaning should be two dimensions of extramusical meaning,owing to the imitation of expressions in music.Congenital amusia(hereafter amusia),commonly known as “tone deafness” or “tune deafness”,is a neurogenetic disorder of musical pitch processing.Despite the core deficits in discriminating fine-grained musical pitch and perceiving melodic contour or pitch direction,amusic individuals showed poor performances in explicitly judging musical structure such as syntax and hierarchical pitch relations.Furthermore,they showed intact musical meaning processing for natural musical excerpts,but not for musical excerpts,in which musical meaning was conveyed by pitch direction,as the evidence by the absence of an N400 effect.Given amusia is from birth,individuals with amusia have become a big problem for music education.Indeed,the effects of musical training in pitch discrimination are very limited in amusia.The aims of the study were to investigate the neural basis of extra-musical intramusical meaning processing in individuals with amusia,and the extent to which music training could improve the processing of musical meaning in amusia.In order to better localize the neural basis of this degraded processing of iconic musical meaning,Experiment 1 used functional magnetic resonance imaging(fMRI)to test individuals with and without amusia with iconic musical meaning processing.The iconic musical meaning was represented by the direction of pitch change.The results showed that amusics as compared with controls showed reduced activation changes in the right middle temporal gyrus and inferior frontal gyrus.Experiment 2 and 3 using event-related potentials(ERPs)examined an electrophysiological correlate of neural representation of emotional musical meaning processing in individuals with amusia.The consonance and structure of chords were manipulated respectively to convey different emotions in the two experiments.Unlike controls,amusics failed to elicit an N400 effect when musical meaning was represented by the consonance and structure of chords.Experiment 4 and 5 used ERPs to investigate an electrophysiological correlate of neural representation of intra-musical meaning processing in individuals with amusia.The two experiments manipulated the chord(s)violations at the final or middle position of chord sequences respectively.The findings revealed that amusic individuals compared with controls did not elicit an N5 effect when musical meaning was represented by both the local and long-distance violations.These experiments above demonstrated that conscious use of knowledge about structural regularities in tonal music in amusia was likely reduced,but this knowledge was intact.Based on this result,Experiment 6 probed into the role of music training in processing the musical meaning.This experiment attempted to make amusics' implicit or tacit knowledge expressed through the use of metaphors.Prior to music training,amusics failed to discriminate the difference between regular and irregular melodies and generate an early right anterior negativity(ERAN)effect.However,after undertaking 9-session music training programs over 4.5 weeks,amusics exhibited significant improvements in distinguishing regular from irregular melodies and elicit the ERAN effect.Furthermore,amusics' performance reached a normal level.These findings indicated that individuals with amusia showed inferior performance on both extra-musical and intra-musical meaning processing as compared to controls.It is likely that the poorer performance of amusic individuals relate to conscious access to the implicit knowledge of regularities in tonal music.Nevertheless,short-term music training enhanced their explicit processing in musical meaning at the behavioral and neural level.This is the first study to explore the neural basis of musical meaning processing in individuals with amusia and the effect of musical training on the processing of musical meaning.music can improve The findings contribute to understand the processing of musical meaning in amusics,answer the question as to whether and to what extent the understanding of musical meaning is universal in humans,and provide evidence for music education.