Patterns of regional cerebral blood flow during attempted reading aloud by stutterers both on and off haloperidol medication: Evidence for inadequate left frontal activation during stuttering

Two stutterers, both recent college graduates, were subjected to regional cerebral blood flow measurements while attempting to read aloud. Each one received two measurements, one of which was under the influence of haloperidol, 3 mg daily. Both subjects showed improvement on medication, allowing a stuttering versus essentially no stuttering comparisons for each subject. Both subjects showed higher Broca's area flow in the right compared to the left hemisphere, during stuttering. Both showed higher Wernicke's area flow in the left compared to the right hemisphere, however, during stuttering. During reading aloud without stuttering, however, the Brocas's area flows were reversed, now showing a left hemisphere advantage. The results were interpreted as consistent with H. M. Sussman and P. F. MacNeilage's (1975, Neuropsychologia, 13, 19–26) proposal that stutterers exhibit conventional left cerebral dominance for speech reception, but inadequate left cerebral dominance for speech production.     

Speech lateralization in deaf populations: evidence for a developmental critical period

Cerebral lateralization for speech in right-handed normal hearing and deaf adolescents was assessed using the dual-task paradigm. Subjects with normal hearing and deafness acquired after 3 years of age displayed left hemispheric dominance for speech production, whereas both congenitally deaf and those with an early acquired deafness (onset 6-36 months) showed atypical, anomalous cerebral representation. These results suggest the presence of a developmental critical period for cerebral lateralization during which exposure to adequate environmental stimulation may be needed to activate left hemispheric dominance for speech.     

The effects of linguistic experience on cerebral lateralization for speech production in normal hearing and deaf adolescents

The cerebral lateralization patterns for speech production in 57 normal hearing and deaf adolescents were studied using the dual-task paradigm. Normal hearing subjects showed left hemispheric dominance for speech production, whereas both the congenitally deaf and those with early acquired deafness showed atypical cerebral representation for speech production. Deaf subjects whose hearing loss occurred after 2 years of age displayed a pattern of mixed cerebral dominance related to complexity of speech production or task difficulty. These results are interpreted as evidence for a relationship between linguistic/cognitive stage of development and the ontogenesis of cerebral lateralization. A parallel lateralization hypothesis of left cerebral dominance for speech production is offered.     

Some effects of the Edinburgh Masker on stuttering during oral reading and spontaneous speech

This study assessed the effect of a voice-activated masking unit, known as the Edinburgh Masker, on the speech of four stutterers during oral reading and spontaneous speech. The results show that one stutterer reduced stuttering almost completely whenever the masker was activated. Two subjects showed either marginal or temporary reductions of stuttering during one speaking condition but showed no change in the other condition. The other subject reduced stuttering only during spontaneous speech. No reduction in stuttering was associated with reduced speech rate. A perceptual analysis procedure conducted to assess for altered speech quality during masking conditions found changes in speech quality were evident in two subjects. The clinical implications of these findings are discussed.     

Dichotic ear preferences of stuttering children and adults.

39 stutterers and 39 normal speakers indicated their ear preferences for dichotically presented words and digits. A single response mode for both dichotic words and digits was selected to study speech perception. Stutterers showed significantly less of the normal right-ear preference for dichotic words and digits than non-stutterers. The proportion of stutterers who failed to demonstrate a right-ear preference for dichotic words was significantly greater than for non-stutterers. 18% of the stutterers and none of the non-stutterers showed reversed or a left-ear preference for dichotic digits. Although non-stuttering children and adults performed alike on the dichotic tasks, the right-ear dichotic-words scores of stuttering children were significantly smaller than those of adult stutterers. The results are related to an early notion that stuttering may be related to mixed dominance and recent evidence showing that large percentages of older stuttering children show spontaneous remission of stuttering.     

Stuttering treatment control using P300 event-related potentials

Positron emission tomography studies during speech have indicated a failure to show the normal activation of auditory cortical areas in stuttering individuals. In the present study, P300 event-related potentials were used to investigate possible effects of behavioral treatment on the pattern of signal amplitude and latency between waves. In order to compare variations in P300 measurements, a control group paired by age and gender to the group of stutterers, was included in the study. Findings suggest that the group of stutterers presented a significant decrease in stuttering severity after the fluency treatment program. Regarding P300 measurements, stutterers and their controls presented results within normal limits in all testing situations and no significant statistical variations between pre and post treatment testing. When comparing individual results between the testing situations, stutterers presented a higher average decrease in wave latency for the right ear following treatment. The results are discussed in light of previous P300 event-related potentials and functional imaging studies with stuttering adults.Educational objectives: The reader will learn about and be able to describe the: (1) use of P300 event-related potentials in the study of stuttering; (2) differences between stuttering and non-stuttering adults; and (3) effects of behavioral fluency treatment on cerebral activity in stuttering speakers.     

Reprint of: stuttering treatment control using P300 event-related potentials

Positron emission tomography studies during speech have indicated a failure to show the normal activation of auditory cortical areas in stuttering individuals. In the present study, P300 event-related potentials were used to investigate possible effects of behavioral treatment on the pattern of signal amplitude and latency between waves. In order to compare variations in P300 measurements, a control group paired by age and gender to the group of stutterers, was included in the study. Findings suggest that the group of stutterers presented a significant decrease in stuttering severity after the fluency treatment program. Regarding P300 measurements, stutterers and their controls presented results within normal limits in all testing situations and no significant statistical variations between pre and post treatment testing. When comparing individual results between the testing situations, stutterers presented a higher average decrease in wave latency for the right ear following treatment. The results are discussed in light of previous P300 event-related potentials and functional imaging studies with stuttering adults.Educational objectives: The reader will learn about and be able to describe the: (1) use of P300 event-related potentials in the study of stuttering; (2) differences between stuttering and non-stuttering adults; and (3) effects of behavioral fluency treatment on cerebral activity in stuttering speakers.     

The effect of SpeechEasy on stuttering frequency, speech rate, and speech naturalness

The effects of SpeechEasy on stuttering frequency, stuttering severity self-ratings, speech rate, and speech naturalness for 31 adults who stutter were examined. Speech measures were compared for samples obtained with and without the device in place in a dispensing setting. Mean stuttering frequencies were reduced by 79% and 61% for the device compared to the control conditions on reading and monologue tasks, respectively. Mean severity self-ratings decreased by 3.5 points for oral reading and 2.7 for monologue on a 9-point scale. Despite dramatic reductions in stuttering frequency, mean global speech rates in the device condition increased by only 8% in the reading task and 15% for the monologue task, and were well below normal. Further, complete elimination of stuttering was not associated with normalized speech rates. Nevertheless, mean ratings of speech naturalness improved markedly in the device compared to the control condition and, at 3.3 and 3.2 for reading and monologue, respectively, were only slightly outside the normal range. These results show that SpeechEasy produced improved speech outcomes in an assessment setting. However, findings raise the issue of a possible contribution of slowed speech rate to the stuttering reduction effect, especially given participants' instructions to speak chorally with the delayed signal as part of the active listening instructions of the device protocol. Study of device effects in situations of daily living over the long term is necessary to fully explore its treatment potential, especially with respect to long-term stability. Educational objectives: The reader will be able to discuss and evaluate: (1) issues pertinent to evaluating treatment benefits of fluency aids and (2) the effects of SpeechEasy on stuttering frequency, speech rate, and speech naturalness during testing in a dispensing setting for a relatively large sample of adults who stutter.     

Electroencephalographic and dichotic indices of cerebral laterality in stutterers

To test the hypothesis that stuttering is the product of faulty cerebral laterality four experiments were performed on each of five adult stutterers and five fluent speakers. These tests were: (1) dichotic listening with consonant-vowel pairs, (2) alpha recording over both hemispheres during the performance of cognitive tasks intended to engage preferentially the left or right hemispheres, (3) contingent negative variation with either an articulatory or bilaterally symmetrical response, and (4) readiness potential with the same responses. The results fail to disconfirm the null hypothesis regarding stutterers and their fluent peers. All subjects showed consistent patterns of cerebral laterality indicative of localization of speech function in the left hemisphere. Suggestions are made regarding a possible contribution of deficient sensorimotor integration in stuttering.     

Effect of reading with reversed speech on frequency of stuttering in adults

This study explored the effect of reading with reversed speech on the frequency of stuttering. Eight adults who stutter served as participants and read four 300-syllable passages while listening to three types of speech stimuli: normal speech (choral reading), reversed speech at normal speed, reversed speech at half speed, and a control condition of no auditory feedback. A repeated-measures analysis of variance showed a significant decrease in stuttering frequency in the choral reading condition but not in reversed speech at normal and half speed. However, the reversed speech at half-speed condition showed a large effect size (omega2 = 0.32). Data suggest that a forward moving speech feedback is not essential to decrease the frequency of stuttering in adults who stutter.     

Evaluation and elimination of an avoidance response in a child who stutters: A case study

In this case study, efforts to treat stuttering in a 6-year-old male with cerebral palsy were complicated by frequent replies of “I don't know” that allowed the child to avoid more extensive answers to conversational questions. Following a program of extinction plus differential reinforcement of alternative behavior (DRA), the response “I don't know” was decreased while both speech rate and stuttering increased. Simplified habit reversal (SHR) techniques (controlled breathing) were then applied and resulted in a reduction of stuttering and maintenance of low rates of avoidance. A reversal to baseline resulted in initially high levels of avoidance and low levels of stuttering, with these trends reversing as baseline continued. The SHR treatment for stuttering was then reimplemented and stuttering rates again decreased while avoidance rates remained low, Implications are discussed.     

Cerebral specialization for speech production in persons with Down syndrome.

The study of cerebral specialization in persons with Down syndrome (DS) has revealed an anomalous pattern of organization. Specifically, dichotic listening studies (e.g., Elliott & Weeks, 1993) have suggested a left ear/right hemisphere dominance for speech perception for persons with DS. In the current investigation, the cerebral dominance for speech production was examined using the mouth asymmetry technique. In right-handed, nonhandicapped subjects, mouth asymmetry methodology has shown that during speech, the right side of the mouth opens sooner and to a larger degree then the left side (Graves, Goodglass, & Landis, 1982). The phenomenon of right mouth asymmetry (RMA) is believed to reflect the direct access that the musculature on the right side of the face has to the left hemisphere's speech production systems. This direct access may facilitate the transfer of innervatory patterns to the muscles on the right side of the face. In the present study, the lateralization for speech production was investigated in 10 right-handed participants with DS and 10 nonhandicapped subjects. A RMA at the initiation and end of speech production occurred for subjects in both groups. Surprisingly, the degree of asymmetry between groups did not differ, suggesting that the lateralization of speech production is similar for persons with and persons without DS. These results support the biological dissociation model (Elliott, Weeks, & Elliott, 1987), which holds that persons with DS display a unique dissociation between speech perception (right hemisphere) and speech production (left hemisphere).     

The speech naturalness of people who stutter speaking under delayed auditory feedback as perceived by different groups of listeners

This study investigated listeners' perception of the speech naturalness of people who stutter (PWS) speaking under delayed auditory feedback (DAF) with particular attention for possible listener differences. Three panels of judges consisting of 14 stuttering individuals, 14 speech language pathologists, and 14 naive listeners rated the naturalness of speech samples of stuttering and non-stuttering individuals using a 9-point interval scale. Results clearly indicate that these three groups evaluate naturalness differently. Naive listeners appear to be more severe in their judgements than speech language pathologists and stuttering listeners, and speech language pathologists are apparently more severe than PWS. The three listener groups showed similar trends with respect to the relationship between speech naturalness and speech rate. Results of all three indicated that for PWS, the slower a speaker's rate was, the less natural speech was judged to sound. The three listener groups also showed similar trends with regard to naturalness of the stuttering versus the non-stuttering individuals. All three panels considered the speech of the non-stuttering participants more natural. EDUCATIONAL OBJECTIVES: The reader will be able to: (1) discuss the speech naturalness of people who stutter speaking under delayed auditory feedback, (2) discuss listener differences about the naturalness of people who stutter speaking under delayed auditory feedback, and (3) discuss the importance of speech rate for the naturalness of speech.     

Cerebral lateralization for speech in deaf and normal children

The cerebral lateralization pattern for speech production in normal hearing and congenitally deaf children was studied using the dual-task paradigm. Performance under the verbal task conditions showed predicted left hemispheric dominance for speech production in the normal hearing children. No developmental trends in asymmetry were found, suggesting that speech lateralization is present in normal 3-year-old children. These data support the developmental invariance hypothesis of cerebral organization. Deaf children showed more symmetrical patterns of cerebral control for speech production. No developmental trends in functional brain organization were observed among prepubescent deaf children.     

Stuttering: a dynamic motor control disorder

The purpose of this review is to determine what neural mechanisms may be dysfunctional in stuttering. Three sources of evidence are reviewed. First, studies of dynamic inter-relationships among brain regions during normal speech and in persons who stutter (PWS) suggest that the timing of neural activity in different regions may be abnormal in PWS. Second, the brain lesions associated with acquired stuttering are reviewed. These indicate that in a high percentage of cases, the primary speech and language regions are not affected but lesions involve other structures, such as the basal ganglia, which may modulate the primary speech and language regions. Third, to characterize the motor control disorder in stuttering, similarities and differences from focal dystonias such as spasmodic dysphonia (SD) and Tourette’s syndrome (TS) are reviewed. This review indicates that the central control abnormalities in stuttering are not due to disturbance in one particular brain region but rather a system dysfunction that interferes with rapid and dynamic speech processing for production.

Educational objectives: The reader will be able to describe: (1) the similarities and differences between stuttering and other speech motor control disorders, (2) which brain lesions are most likely to produce acquired stuttering in adults, and (3) what type of brain abnormality most likely underlies stuttering.     

Life experiences of people who stutter, and the perceived impact of stuttering on quality of life: personal accounts of South African individuals

The purpose of the study was to investigate the life experiences of a group of South African adults who stutter and the impact of stuttering on their quality of life. Participants were 16 adults with a mean age of 28.9 and ranging from 20 to 59 years. Methods involved individual interviews designed to explore the life domains of education; social life; employment; speech therapy; family and marital life; and identity, beliefs and emotional issues. Main findings of the study indicated that the majority of participants perceived their stuttering to have impacted on their academic performance at school, and relationships with teachers and classmates. Although their stuttering was not perceived to adversely influence their ability to establish friendships, people generally reacted negatively to their stuttering. Many felt that their stuttering did not have an adverse effect on their choice of occupation, ability to obtain work, and relationships with managers and co-workers, although it was perceived to influence their work performance and hamper their chances for promotion. Although the majority viewed their speech therapy experiences as being negative; more than half the sample believed that speech therapy had, nevertheless exerted a positive effect on their quality of life. Overall, stuttering did not appear to have influenced participants’ family and marital life. Most participants felt that stuttering had affected their self-esteem and self-image, and had evoked strong emotions within them. Findings are taken to suggest the need to incorporate subjective feelings about stuttering into the clinical practice of speech-language therapy; to provide information and coping strategies for teachers and employers; and for further research.

Educational objectives: After completing this activity, the reader will be able to: (1) describe and explain the perceived impact of stuttering on quality of life in terms of education; social life; employment; speech therapy; family and marital life; and identity, beliefs and emotional issues; (2) to interpret and utilize the subjective meanings that individuals attach to their stuttering to improve stuttering treatment, counseling and research.     

The morphological asymmetry of the hemispheres and cerebral dominance for speech: A possible relationship

The asymmetry of the posterior Sylvian branches of the middle cerebral artery was examined on the carotid angiograms of 59 patients in whom the lateralization of speech representation was known from sodium amobarbital (Amytal) studies. The usual asymmetry of these vessels was found to be present in the group of patients with left-hemisphere speech representation but significantly reduced in patients with atypical cerebral dominance for speech. A model of the inheritance of handedness and cerebral dominance is extended to take account of these results.     

发展性口吃的脑机制

口吃是一种常见的言语障碍,对此曾提出过大脑半球言语功能偏侧化异常假设。近期,发展性口吃的神经成像研究在支持这一经典假设的同时,还发现负责言语监控的颞叶系统和负责言语运动控制的额叶系统与皮层下脑结构存在功能失调,这可能损害言语产生时的精确时间控制。据此,研究者开始用神经网络的观点来解释发展性口吃产生的脑机制,认为患者可能存在由多个言语产生相关脑区构成的“双通路”网络的功能障碍     

Comparing judgments of stuttering made by students, clinicians, and highly experienced judges

Purpose: The purpose of this study was to compare judgments of stuttering made by students and clinicians with previously available judgments made by highly experienced judges in stuttering. Method: On two occasions, 41 university students and 31 speech-language pathologists judged the presence or absence of stuttering in each of 216 audiovisually recorded 5-s intervals of the speech of adults who stutter. Intrajudge and interjudge agreement were calculated, and comparisons were made to judgments previously made about the same recordings by 10 highly experienced judges of stuttering. Results: Students and clinicians showed similar and relatively high levels of intrajudge and interjudge agreement, but both students and clinicians identified less than half as much stuttering as the highly experienced judges had identified. Conclusions: These results replicate previous findings of high agreement coexisting with low accuracy in students’ judgments of stuttering, extending those findings to show that similar problems are evident in judgments made by practicing clinicians. Implications include the need for explicit stuttering judgment training programs for both students and practicing clinicians.

Educational objectives: After reading this article, the reader will be able to: (1) describe different methods for identifying stuttering and possible problems associated with each method; (2) describe two different methods for reporting interjudge reliability; (3) describe how the identification of stuttering differs for student, clinician, and highly experienced judges.