Stuttering Min oscillations within E. coli bacteria: A stochastic polymerization model

We have developed a 3D off-lattice stochastic polymerization model to study subcellular oscillation of Min proteins in the bacteria Escherichia coli, and used it to investigate the experimental phenomenon of Min oscillation stuttering. Stuttering was affected by the rate of immediate rebinding of MinE released from depolymerizing filament tips (processivity), protection of depolymerizing filament tips from MinD binding, and fragmentation of MinD filaments due to MinE. Each of processivity, protection, and fragmentation reduces stuttering, speeds oscillations, and reduces MinD filament lengths. Neither processivity or tip-protection were, on their own, sufficient to produce fast stutter-free oscillations. While filament fragmentation could, on its own, lead to fast oscillations with infrequent stuttering; high levels of fragmentation degraded oscillations. The infrequent stuttering observed in standard Min oscillations are consistent with short filaments of MinD, while we expect that mutants that exhibit higher stuttering frequencies will exhibit longer MinD filaments. Increased stuttering rate may be a useful diagnostic to find observable MinD polymerization in experimental conditions.Comment: 21 pages, 7 figures, missing unit for k_f inserte

The effects of bilingualism on speakers who stutter during late childhood

Objectives: To examine stuttering by children speaking an alternative language exclusively (LE) or with English (BIL) and to study onset of stuttering, school performance and recovery rate relative to monolingual speakers who stutter (MONO). Design: Clinical referral sample with supplementary data obtained from speech recordings and interviews. Setting: South-East England, 1999–2007. Participants: Children aged 8–12 plus who stuttered (monolingual and bilingual) and fluent bilingual controls (FB). Main outcome measures: Participants’ stuttering history, SATS scores, measures of recovery or persistence of stuttering. Results: 69 (21.8%) of 317 children were bilingual. Of 38 children who used a language other than English at home, 36 (94.7%) stuttered in both languages. Fewer LE (15/38, 39.5%) than BIL (23/38, 60.5%) children stuttered at first referral to clinic, but more children in the fluent control sample were LE (28/38, 73.7%) than BIL (10/38, 26.3%). The association between stuttering and bilingual group (LE/BIL) was significant by x2 test; BIL speakers have more chance of stuttering than LE speakers. Age at stuttering onset and male/female ratio for LE, BIL and MONO speakers were similar (4 years 9 months, 4 years 10 months and 4 years 3 months, and 4.1:1, 4.75:1 and 4.43:1, respectively). Educational achievement was not affected by bilingualism relative to the MONO and FB groups. The recovery rate for the LE and MONO controls together (55%) was significantly higher by x2 test than for the BIL group (25%). Conclusions: BIL children had an increased risk of stuttering and a lower chance of recovery from stuttering than LE and MONO speakers

The Effects of Altered Auditory Feedback (AAF) on Fluency in Adults Who Stutter: A Systematic Review

Background and Objectives: Stuttering affects 70 million people worldwide, which is about 1% of the population. Altered auditory feedback (AAF) is a process by which an individual’s auditory speech signal is electronically changed to temporarily increase the fluency of a person who stutters. For the purpose of this systematic review, AAF includes delayed auditory feedback (DAF) and frequency-altered feedback (FAF). This systematic review examines fluency enhancement in adults who stutter when using AAF devices. Methods: A review of the literature was searched using PubMed, Ovid MEDLINE, PsycINFO, and CINAHL databases with key search terms related to stuttering and AAF. Inclusion criteria included: 1) adults ages ≥ 18 years old who stutter, 2) comparison of altered auditory feedback forms and/or no altered auditory feedback forms in the treatment of stuttering, 3) inclusion of DAF or FAF, 4) outcomes related to aspects of stuttering or people who stutter (e.g., fluency level, speech naturalness, speech rate), and 5) experimental research. Studies were quality assessed and rated by the authors. Results: A total of 16 articles were included in this review. Articles were of ‘moderate’ quality. Conclusions: AAF devices are generally effective in reducing stuttering frequency, with most notable fluency enhancement occurring during oral reading. The degree of fluency enhancement between individuals who stutter is variable and is influenced by factors such as stuttering severity. While research generally supports the use of AAF devices in reducing stuttering frequency, there are inconsistent findings regarding speech naturalness. AAF is likely most effective when used in conjunction with traditional speech therapy. Further research is needed to better understand the relationship between AAF and stuttering, particularly regarding unstructured speaking tasks and speech naturalness.https://scholarworks.uvm.edu/csdms/1004/thumbnail.jp

Anomalous morphology in left hemisphere motor and premotor cortex of children who stutter

Stuttering is a neurodevelopmental disorder that affects the smooth flow of speech production. Stuttering onset occurs during a dynamic period of development when children first start learning to formulate sentences. Although most children grow out of stuttering naturally, ∼1% of all children develop persistent stuttering that can lead to significant psychosocial consequences throughout one’s life. To date, few studies have examined neural bases of stuttering in children who stutter, and even fewer have examined the basis for natural recovery versus persistence of stuttering. Here we report the first study to conduct surface-based analysis of the brain morphometric measures in children who stutter. We used FreeSurfer to extract cortical size and shape measures from structural MRI scans collected from the initial year of a longitudinal study involving 70 children (36 stuttering, 34 controls) in the 3–10-year range. The stuttering group was further divided into two groups: persistent and recovered, based on their later longitudinal visits that allowed determination of their eventual clinical outcome. A region of interest analysis that focused on the left hemisphere speech network and a whole-brain exploratory analysis were conducted to examine group differences and group × age interaction effects. We found that the persistent group could be differentiated from the control and recovered groups by reduced cortical thickness in left motor and lateral premotor cortical regions. The recovered group showed an age-related decrease in local gyrification in the left medial premotor cortex (supplementary motor area and and pre-supplementary motor area). These results provide strong evidence of a primary deficit in the left hemisphere speech network, specifically involving lateral premotor cortex and primary motor cortex, in persistent developmental stuttering. Results further point to a possible compensatory mechanism involving left medial premotor cortex in those who recover from childhood stuttering.This study was supported by Award Numbers R01DC011277 (SC) and R01DC007683 (FG) from the National Institute on Deafness and other Communication Disorders (NIDCD). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIDCD or the National Institutes of Health. (R01DC011277 - National Institute on Deafness and other Communication Disorders (NIDCD); R01DC007683 - National Institute on Deafness and other Communication Disorders (NIDCD))Accepted manuscrip

Stuttering generalization self-measure: preliminary development of a self-measuring tool

Objectives: The reader will become knowledgeable about 1) the relationship between stuttering severity and speech-anxiety level, and 2) the importance of assessing the generalization effect in different social speaking situations. Additionally, the reader will understand the processes of validating the Stuttering Generalization Self-Measure. Abstract Introduction: Generalization of treatment is considered a difficult task for clinicians and people who stutter (PWS), and can constitute a barrier to long-term treatment success. To our knowledge, there are no standardized tests that collect measurement of the behavioral and cognitive aspects alongside the client’s self-perception in real-life speaking situations. Purpose: This paper describes the development of a Stuttering Generalization Self-Measure (SGSM). The purpose of SGSM is to assess 1) stuttering severity and 2) speech-anxiety level during real-life situations as perceived by PWS. Additionally, this measurement aims to 3) investigate correlations between stuttering severity and speech-anxiety level within the same real-life situation. Method: The SGSM includes speaking situations that are developed to cover a variety of frequent speaking situations. These items were created according to five listener categories (family and close friends, acquaintances, strangers, persons of authority, and giving a short speech to small audience). Forty-three participants (22 PWS, and 21 control) aged 18 to 53 years were asked to complete the assessment in real-life situations. Results: Preliminary analyses indicated that test-retest reliability was high for both groups. Discriminant validity was also achieved as the SGSM scores significantly differed between the two groups for stuttering and speech-anxiety. Convergent validity was confirmed by significant correlations between the SGSM and other speech-related anxiety measures

Involvement of the cortico-basal ganglia-thalamocortical loop in developmental stuttering

Stuttering is a complex neurodevelopmental disorder that has to date eluded a clear explication of its pathophysiological bases. In this review, we utilize the Directions Into Velocities of Articulators (DIVA) neurocomputational modeling framework to mechanistically interpret relevant findings from the behavioral and neurological literatures on stuttering. Within this theoretical framework, we propose that the primary impairment underlying stuttering behavior is malfunction in the cortico-basal ganglia-thalamocortical (hereafter, cortico-BG) loop that is responsible for initiating speech motor programs. This theoretical perspective predicts three possible loci of impaired neural processing within the cortico-BG loop that could lead to stuttering behaviors: impairment within the basal ganglia proper; impairment of axonal projections between cerebral cortex, basal ganglia, and thalamus; and impairment in cortical processing. These theoretical perspectives are presented in detail, followed by a review of empirical data that make reference to these three possibilities. We also highlight any differences that are present in the literature based on examining adults versus children, which give important insights into potential core deficits associated with stuttering versus compensatory changes that occur in the brain as a result of having stuttered for many years in the case of adults who stutter. We conclude with outstanding questions in the field and promising areas for future studies that have the potential to further advance mechanistic understanding of neural deficits underlying persistent developmental stuttering.R01 DC007683 - NIDCD NIH HHS; R01 DC011277 - NIDCD NIH HHSPublished versio

Auditory-motor adaptation is reduced in adults who stutter but not in children who stutter

Previous studies have shown that adults who stutter produce smaller corrective motor responses to compensate for unexpected auditory perturbations in comparison to adults who do not stutter, suggesting that stuttering may be associated with deficits in integration of auditory feedback for online speech monitoring. In this study, we examined whether stuttering is also associated with deficiencies in integrating and using discrepancies between expect ed and received auditory feedback to adaptively update motor programs for accurate speech production. Using a sensorimotor adaptation paradigm, we measured adaptive speech responses to auditory formant frequency perturbations in adults and children who stutter and their matched nonstuttering controls. We found that the magnitude of the speech adaptive response for children who stutter did not differ from that of fluent children. However, the adaptation magnitude of adults who stutter in response to formant perturbation was significantly smaller than the adaptation magnitude of adults who do not stutter. Together these results indicate that stuttering is associated with deficits in integrating discrepancies between predicted and received auditory feedback to calibrate the speech production system in adults but not children. This auditory-motor integration deficit thus appears to be a compensatory effect that develops over years of stuttering

Effects Of Length, Complexity, And Grammatical Correctness On Stuttering In Spanish-Speaking Preschool Children

Purpose: To explore the effects of utterance length, syntactic complexity, and grammatical correctness on stuttering in the spontaneous speech of young, monolingual Spanish-speaking children. Method: Spontaneous speech samples of 11 monolingual Spanish-speaking children who stuttered, ages 35 to 70 months, were examined. Mean number of syllables, total number of clauses, utterance complexity (i.e., containing no clauses, simple clauses, or subordinate and/or conjoined clauses), and grammatical correctness (i.e., the presence or absence of morphological and syntactical errors) in stuttered and fluent utterances were compared. Results: Findings revealed that stuttered utterances in Spanish tended to be longer and more often grammatically incorrect, and contain more clauses, including more subordinate and/or conjoined clauses. However, when controlling for the interrelatedness of syllable number and clause number and complexity, only utterance length and grammatical incorrectness were significant predictors of stuttering in the spontaneous speech of these Spanish-speaking children. Use of complex utterances did not appear to contribute to the prediction of stuttering when controlling for utterance length. Conclusions: Results from the present study were consistent with many earlier reports of English-speaking children. Both length and grammatical factors appear to affect stuttering in Spanish-speaking children. Grammatical errors, however, served as the greatest predictor of stuttering.Communication Sciences and Disorder

The Kid's Speech: The Effect of Stuttering on Human Capital Acquisition

A number of studies have shown that childhood speech impairments such as stuttering are associated with lower test scores and educational attainment. However, it is unclear whether this result is causal in nature or whether it can be explained by difficult-to-measure heterogeneity at the community, family, or individual level. Using data from the National Longitudinal Study of Adolescent Health and ordinary least squares, we show that stuttering is negatively associated with high school grades, the probability of high school graduation, and the probability of college attendance. However, empirical specifications with family fixed effects or controls for learning disabilities such as Attention Deficit Hyperactivity Disorder suggest that these associations can, in large part, be explained by difficult-to-measure heterogeneity.speech impairment, stuttering, human capital, educational attainment