The Neural Mechanism Of Stutters In Rhythm Boundary Processing

Stuttering is a kind of speech rhythm disorder.According to research by the World Health Organization(WHO,2010),stuttering refers that the flow of speech is interrupted by involuntary repetitions and prolongations of sounds,syllables,words or phrases.Stuttering is also accompanied with some concomitant symptoms such as facial pain,compulsive efforts,and involuntary blink whereas these symptoms could potentially worsen expression.As a high morbidity disease,stuttering causes many negative impacts in the patients' life and work.Therefore,the necessity of the research in stutter's processing of prosodic information is obvious.This crucial research could not only provide theoretical support for the construction of a complete model of psychological linguistics,but also reveal the essence of stuttering and provide scientific guidance for stuttering treatment.Since the most obvious symptom of stuttering is expression obstacles,many researches on stuttering show their attention on processing defects in speech production.However,due to the complexity of stuttering,consistent conclusions on processing defects in these studies have yet to be obtained.The production and perception of speech contains similar cognitive and neural basis which means the speech perception process has important influence on production.The researchers have examined whether stutterers' language processing is different from normal adults in the aspects of phonetic,syntactic,and semantic.An important achievement has been made in this area.However,there are still many unclear aspects which worth further investigating.Meanwhile,the characteristics of stutter's prosodic information processing capability have not been examined.This study uses event-related potential(ERP)technology to explore the stutter's cognitive and neural mechanism of perception and processing of explicit prosodic boundary.The implicit prosodic boundary is also studied while our participants listening to oral speech in order to investigate the prosodic priming effect and its related neural responses in different stimuli-presenting mode when stutters process different kinds of prosodic boundary.Firstly,language fluency of subjects with professional scale is evaluated,then the sentence is presented(Study 1:ditterent hierarchical prosodic boundaries in four sentence in a group),whereas the participants were asked to complete the sentence comprehension task.Secondly,rendering the phrase(Study 2:pairs of ambiguous phrases),using priming paradigm,let the participants complete lexical and structural judgement tasks.The two research ERP data are combined to discuss stuttering and verbal fluency in the sense of rhythm boundary in cognitive neural mechanisms.ERP results,(1)Phonological phrase intonation phrase boundaries in the Chinese sentence failed to induce significant as reflected by stable boundary processing of the specific electrical components(CPS,Closure Positive Shift)with stutterers and normal subjects.Moreover,the stutter's elicited in the perception of phonological phrase is more positive than fluency speaker.(2)Regardless of lexical decision task or structure tasks of ambiguous phrase rhythm priming,the priming effects induced by stuttering are significantly greater than normal people,especially in structure task.In addition,different types of ambiguous phrases elicited priming effects different.The results above have indicated that the stuttering is more sensitive to rhythm information than the verbal fluency people.This study reveals that the neural mechanisms of stuttering and verbal fluency people are different in the process of speech perception.Stuttering is more sensitive than verbal fluency people in the process of speech perception.This research helps to expand people's awareness in speech perception of prosodic information and further understanding of the impact in speech production process of stuttering.This research also shows that the effect of environmental factors which cause stutter should be taken into account at the stage of learning language.