Peter Howell

Relationship between Speech Production and Perception in People Who Stutter

Speech production difficulties are apparent in people who stutter (PWS). PWS also have difficulties in speech perception compared to controls. It is unclear whether the speech perception difficulties in PWS are independent of, or related to, their speech production difficulties. To investigate this issue, functional MRI data were collected on 13 PWS and 13 controls whilst the participants performed a speech production task and a speech perception task. PWS performed poorer than controls in the perception task and the poorer performance was associated with a functional activity difference in the left anterior insula (part of the speech motor area) compared to controls. PWS also showed a functional activity difference in this and the surrounding area [left inferior frontal cortex (IFC)/anterior insula] in the production task compared to controls. Conjunction analysis showed that the functional activity differences between PWS and controls in the left IFC/anterior insula coincided across the perception and production tasks. Furthermore, Granger Causality Analysis on the resting-state fMRI data of the participants showed that the causal connection from the left IFC/anterior insula to an area in the left primary auditory cortex (Heschl’s gyrus) differed significantly between PWS and controls. The strength of this connection correlated significantly with performance in the perception task. These results suggest that speech perception difficulties in PWS are associated with anomalous functional activity in the speech motor area, and the altered functional connectivity from this area to the auditory area plays a role in the speech perception difficulties of PWS.

Planum temporale asymmetry in people who stutter

Highlights • Planum temporale asymmetry was compared in 67 people who stutter and 63 age-matched controls.• Size or asymmetry of the planum temporale did not differ between people who stutter and controls.• The asymmetry of the planum temporale was not affected by stuttering severity.• Differences in asymmetry of the planum temporale are not a cause, consequence or correlate of developmental stuttering.

Identification of fluency and word-finding difficulty in samples of children with diverse language backgrounds

BACKGROUND Stuttering and word-finding difficulty (WFD) are two types of communication difficulty that occur frequently in children who learn English as an additional language (EAL), as well as those who only speak English. The two disorders require different, specific forms of intervention. Prior research has described the symptoms of each type of difficulty. This paper describes the development of a non-word repetition test (UNWR), applicable across languages, that was validated by comparing groups of children identified by their speech and language symptoms as having either stuttering or WFD. AIMS To evaluate whether non-word repetition scores using the UNWR test distinguished between children who stutter and those who have a WFD, irrespective of the childrens first language. METHODS & PROCEDURES UNWR was administered to ninety-six 4-5-year-old children attending UK schools (20.83% of whom had EAL). The childrens speech samples in English were assessed for symptoms of stuttering and WFD. UNWR scores were calculated. OUTCOMES & RESULTS Regression models were fitted to establish whether language group (English only/EAL) and symptoms of (1) stuttering and (2) WFD predicted UNWR scores. Stuttering symptoms predicted UNWR, whereas WFD did not. These two findings suggest that UNWR scores dissociate stuttering from WFD. There were no differences between monolingual English-speakers and children who had EAL. CONCLUSIONS & IMPLICATIONS UNWR scores distinguish between stuttering and WFD irrespective of language(s) spoken, allowing future evaluation of a range of languages in clinics or schools.

Children who stutter exchange linguistic accuracy for processing speed in sentence comprehension

Comprehension of predicates and reflexives was examined in children who stutter (CWS) and children who do not stutter (CWNS) who were between 9 years, 7 months and 10 years, 2 months. Demands on working memory and manual reaction time were also assessed in two experiments that employed a four-choice picture-selection sentence comprehension task. CWS were less accurate than CWNS on the attachment of predicates. For reflexives, there was no between-group difference in accuracy, but there was a difference in speed. The two constructions induced processing at different points on a speed–accuracy continuum with CWS sacrificing accuracy to respond fast with predicates, while they maintained accuracy of reflexives by responding slower relative to CWNS. Predicates made more demands on language than nonspeech motor reaction time, whereas the reverse was the case with reflexives for CWS compared to CWNS.

Reorganization of brain function after a short-term behavioral intervention for stuttering

&NA; This study investigated changes in brain function that occurred over a 7‐day behavioral intervention for adults who stutter (AWS). Thirteen AWS received the intervention (AWS+), and 13 AWS did not receive the intervention (AWS−). There were 13 fluent controls (FC−). All participants were scanned before and after the intervention. Whole‐brain analysis pre‐intervention showed significant differences in task‐related brain activation between AWS and FC− in the right inferior frontal cortex (IFC) and left middle temporal cortex, but there were no differences between the two AWS groups. Across the 7‐day period of the intervention, AWS+ alone showed a significant increase of brain activation in the left ventral IFC/insula. There were no changes in brain function for the other two groups. Further analysis revealed that the change did not correlate with resting‐state functional connectivity (RSFC) that AWS showed in the cerebellum (Lu et al., 2012). However, both changes in task‐related brain function and RSFC correlated with changes in speech fluency level. Together, these findings suggest that functional reorganization in a brain region close to the left IFC that shows anomalous function in AWS, occurs after a short‐term behavioral intervention for stuttering. HighlightsChanges in the left vIFCs function were identified after a short‐term behavioral intervention for stuttering.Changes of brain function in the left vIFC significantly correlated with changes of speech fluency level in adults who stutter.Distinct roles of task‐related changes in the vIFC and task‐independent RSFC changes in the cerebellum were clarified.

Subtypes of stuttering determined by latent class analysis in two Swiss epidemiological surveys

Aims Associations between stuttering in childhood and a broad spectrum of risk factors, associated factors and comorbidities were examined in two large epidemiological studies. Subtypes of stuttering were then identified based on latent class analysis (LCA). Methods Data were from two representative Swiss population samples: PsyCoLaus (N = 4,874, age 35–82 years) and the ZInEP Epidemiology Survey (N = 1,500, age 20–41 years). Associations between stuttering and sociodemographic characteristics, familial aggregation, comorbidity and psychosocial risk / associated factors were investigated in both samples. LCAs were conducted on selected items from people in both samples who reported having stuttered in childhood. Results Initial analyses linked early anxiety disorders, such as separation anxiety disorder and overanxious disorder, to stuttering (PsyCoLaus). ADHD was associated with stuttering in both datasets. In the analyses of risk / associated factors, dysfunctional parental relationships, inter-parental violence and further childhood adversities were mutual predictors of stuttering. Moreover, comorbidities were seen with hay fever, asthma, eczema and psoriasis (PsyCoLaus). Subsequent LCA identified an unspecific group of persons who self-reported that they stuttered and a group defined by associations with psychosocial adversities (ZINEP, PsyCoLaus) and atopic diseases (PsyCoLaus). Conclusions The two subtypes of developmental stuttering have different risk / associated factors and comorbidity patterns. Most of the factors are associated with vulnerability mechanisms that occur early in life and that have also been linked with other neurodevelopmental disorders. Both psychosocial and biological factors appear to be involved in the etiopathogenesis of stuttering.

Relationship between speech-evoked neural responses and perception of speech in noise in older adults

Speech-in-noise (SPIN) perception involves neural encoding of temporal acoustic cues. Cues include temporal fine structure (TFS) and envelopes that modulate at syllable (Slow-rate ENV) and fundamental frequency (F0-rate ENV) rates. Here the relationship between speech-evoked neural responses to these cues and SPIN perception was investigated in older adults. Theta-band phase-locking values (PLVs) that reflect cortical sensitivity to Slow-rate ENV and peripheral/brainstem frequency-following responses phase-locked to F0-rate ENV (FFRENV_F0) and TFS (FFRTFS) were measured from scalp-electroencephalography responses to a repeated speech syllable in steady-state speech-shaped noise (SpN) and 16-speaker babble noise (BbN). The results showed that (1) SPIN performance and PLVs were significantly higher under SpN than BbN, implying differential cortical encoding may serve as the neural mechanism of SPIN performance that varies as a function of noise types; (2) PLVs and FFRTFS at resolved harmonics were significantly related to good SPIN performance, supporting the importance of phase-locked neural encoding of Slow-rate ENV and TFS of resolved harmonics during SPIN perception; (3) FFRENV_F0 was not associated to SPIN performance until audiometric threshold was controlled for, indicating that hearing loss should be carefully controlled when studying the role of neural encoding of F0-rate ENV. Implications are drawn with respect to fitting auditory prostheses.

Identification of neural structures involved in stuttering using vibrotactile feedback

HighlightsDifferences between auditory and vibratory pathways were identified.The effects of stimulating these pathways were studied in people who stutter (PWS).The fluency‐enhancing effects of vibrotactile feedback were confirmed.Differences were noted in the slowing effects when delaying these two pathways.Potential neural structures that may improve the fluency of PWS were identified. &NA; Feedback delivered over auditory and vibratory afferent pathways has different effects on the fluency of people who stutter (PWS). These features were exploited to investigate the neural structures involved in stuttering. The speech signal vibrated locations on the body (vibrotactile feedback, VTF). Eleven PWS read passages under VTF and control (no‐VTF) conditions. All combinations of vibration amplitude, synchronous or delayed VTF and vibrator position (hand, sternum or forehead) were presented. Control conditions were performed at the beginning, middle and end of test sessions. Stuttering rate, but not speaking rate, differed between the control and VTF conditions. Notably, speaking rate did not change between when VTF was delayed versus when it was synchronous in contrast with what happens with auditory feedback. This showed that cerebellar mechanisms, which are affected when auditory feedback is delayed, were not implicated in the fluency‐enhancing effects of VTF, suggesting that there is a second fluency‐enhancing mechanism.

Do Events on One Day Influence the Perception of Stuttering on Subsequent Days

Objective: The reaction of children and adolescents who stutter to their own speech and their perception about how others reacted to them were examined over time. Day-to-day changes in perception of own-speech and emotional impact of others on their stuttering were assessed using the new Daily Questionnaire. Design: Nineteen participants (mean age13.10 years, SD=2.8 years) who attended an intensive stuttering treatment completed the Daily Questionnaire on 19 successive days. Results: The Daily Questionnaire assessed day-to-day experiences of the participants and the influence these experiences had on the participant’s life. Significant cross-lagged panel correlations between the impact of other people’s behavior on the previous day with perception of general speaking abilities on the current day were found and between the emotions reported on the previous day and the perception of their own speaking abilities on the current day. Conclusions: The experiences of children and adolescents who stutter fluctuated over time because of the perception of their own and other people’s behavior. These perceived experiences affected how the participants perceived their speech on subsequent days.