A model of serial order problems in fluent, stuttered and agrammatic speech

The clinical and genetic spectrum of paediatric speech and language disorders

Speech and language disorders are known to have a substantial genetic contribution. Although frequently examined as components of other conditions, research on the genetic basis of linguistic differences as separate phenotypic subgroups has been limited so far. Here, we performed an in-depth characterization of speech and language disorders in 52 143 individuals, reconstructing clinical histories using a large-scale data-mining approach of the electronic medical records from an entire large paediatric healthcare network. The reported frequency of these disorders was the highest between 2 and 5 years old and spanned a spectrum of 26 broad speech and language diagnoses. We used natural language processing to assess the degree to which clinical diagnoses in full-text notes were reflected in ICD-10 diagnosis codes. We found that aphasia and speech apraxia could be retrieved easily through ICD-10 diagnosis codes, whereas stuttering as a speech phenotype was coded in only 12% of individuals through appropriate ICD-10 codes. We found significant comorbidity of speech and language disorders in neurodevelopmental conditions (30.31%) and, to a lesser degree, with epilepsies (6.07%) and movement disorders (2.05%). The most common genetic disorders retrievable in our analysis of electronic medical records were STXBP1 (n = 21), PTEN (n = 20) and CACNA1A (n = 18). When assessing associations of genetic diagnoses with specific linguistic phenotypes, we observed associations of STXBP1 and aphasia (P = 8.57 × 10-7, 95% confidence interval = 18.62-130.39) and MYO7A with speech and language development delay attributable to hearing loss (P = 1.24 × 10-5, 95% confidence interval = 17.46-infinity). Finally, in a sub-cohort of 726 individuals with whole-exome sequencing data, we identified an enrichment of rare variants in neuronal receptor pathways, in addition to associations of UQCRC1 and KIF17 with expressive aphasia, MROH8 and BCHE with poor speech, and USP37, SLC22A9 and UMODL1 with aphasia. In summary, our study outlines the landscape of paediatric speech and language disorders, confirming the phenotypic complexity of linguistic traits and novel genotype-phenotype associations. Subgroups of paediatric speech and language disorders differ significantly with respect to the composition of monogenic aetiologies.

The clinical and genetic spectrum of paediatric speech and language disorders in 52,143 individuals

Speech and language disorders are known to have a substantial genetic contribution. Although frequently examined as components of other conditions, research on the genetic basis of linguistic differences as separate phenotypic subgroups has been limited so far. Here, we performed an in-depth characterization of speech and language disorders in 52,143 individuals, reconstructing clinical histories using a large-scale data mining approach of the Electronic Medical Records (EMR) from an entire large paediatric healthcare network. The reported frequency of these disorders was the highest between 2 and 5 years old and spanned a spectrum of twenty-six broad speech and language diagnoses. We used Natural Language Processing to assess to which degree clinical diagnosis in full-text notes were reflected in ICD-10 diagnosis codes. We found that aphasia and speech apraxia could be easily retrieved through ICD-10 diagnosis codes, while stuttering as a speech phenotype was only coded in 12% of individuals through appropriate ICD-10 codes. We found significant comorbidity of speech and language disorders in neurodevelopmental conditions (30.31%) and to a lesser degree with epilepsies (6.07%) and movement disorders (2.05%). The most common genetic disorders retrievable in our EMR analysis were STXBP1 (n=21), PTEN (n=20), and CACNA1A (n=18). When assessing associations of genetic diagnoses with specific linguistic phenotypes, we observed associations of STXBP1 and aphasia (P=8.57 × 10-7, CI=18.62-130.39) and MYO7A with speech and language development delay due to hearing loss (P=1.24 × 10-5, CI=17.46-Inf). Finally, in a sub-cohort of 726 individuals with whole exome sequencing data, we identified an enrichment of rare variants in synaptic protein and neuronal receptor pathways and associations of UQCRC1 with expressive aphasia and WASHC4 with abnormality of speech or vocalization. In summary, our study outlines the landscape of paediatric speech and language disorders, confirming the phenotypic complexity of linguistic traits and novel genotype-phenotype associations. Subgroups of paediatric speech and language disorders differ significantly with respect to the composition of monogenic aetiologies.

Language sample analysis of conversation samples from school-age children who stutter: The role of syntactic factors in stuttering

INTRODUCTION

The purpose of the study was to compare school-age children who stutter (CWS) and age-matched children who do not stutter (CWNS) in syntactic abilities and syntactic performance.

METHODS

Computerized Language Sample Analysis (LSA) was conducted on the conversation samples obtained from 46 school-age CWS and CWNS between 7 and 16 years (CWS, n = 23). Syntactic abilities were assessed using the Index of Productive Syntax (the IPsyn) and Developmental Sentence Scores (DSS) and mixed effects logistic regression analyses with participants as random effects were conducted to determine if the scores were predictive of group membership. Additionally, the groups were compared in the IPsyn subcategories to assess the use of syntactic structures. Syntactic performance was assessed by: (a) Categorizing the sentences from each conversation sample into high vs. low syntactic complexity categories based on DSS scores and comparing the sentence categories in % stuttered sentences (% SS); and (b) Comparing the groups in the proportion of phrase-level disfluencies (phrase repetitions vs. revisions) that are associated with syntactic planning.

RESULTS

In terms of syntactic abilities, the IPsyn scores interacted with the number of utterances (sample size) used to compute the scores in predicting group membership. In comparison to the CWNS, the CWS obtained higher scores in the IPsyn and the sentence structure subcategory of the IPsyn that were independent of sample size. In terms of syntactic performance: (a) Significantly more sentences were stuttered in the high compared to the low syntactic sentence category; (b) Compared to the CWNS who demonstrated significantly more phrase revisions, the CWS showed comparable and fewer phrase revisions and repetitions. Additionally, post-hoc analysis showed that the CWS used significantly elaborated noun phrases and a similar trend was evident for verb phrase elaborations. A significant association between verb phrase elaborations and%SS was also obtained.

CONCLUSIONS

Findings from the IPsyn and the use of elaborate noun phrases, and to some extent verb phrases, suggested that the CWS used more complex syntax even in shorter conversational samples. More stuttered sentences in the high DSS sentence category, the use of fewer phrase revisions, and the association between stuttering and elaborated verb phrases in the CWS are interpreted to suggest the effects of syntactic planning and reformulation demands on fluency during ongoing articulation.

A reconceptualization of sentence production in post-stroke agrammatic aphasia: the synergistic processing bottleneck model

The language production deficit in post-stroke agrammatic aphasia (PSA-G) tends to result from lesions to the left inferior frontal gyrus (LIFG) and is characterized by a triad of symptoms: fragmented sentences, errors in functional morphology, and a dearth of verbs. Despite decades of research, the mechanisms underlying production patterns in PSA-G have been difficult to characterize. Two major impediments to progress may have been the view that it is a purely morphosyntactic disorder and the (sometimes overzealous) application of linguistic theory without interceding psycholinguistic evidence. In this paper, empirical evidence is examined to present an integrated portrait of language production in PSA-G and to evaluate the assumption of a syntax-specific syndrome. In light of extant evidence, it is proposed that agrammatic language production results from a combination of morphosyntactic, phonomotor, and processing capacity limitations that cause a cumulative processing bottleneck at the point of articulatory planning. This proposed Synergistic Processing Bottleneck model of PSA-G presents a testable framework for future research. The paper ends with recommendations for future research on PSA-G.

Rate of Stuttering and Factors Associated With Speech Fluency Characteristics in Adult Struggling Readers

Stuttering is a disorder that affects about 1% of the population and manifests as speech disfluencies. Reading difficulties and disabilities are commonly found in this population. Nonetheless, speech disfluencies have not been explored in adult struggling readers (ASRs). In the current study, we examined the rate of stuttering in ASRs as well as the relationships between their speech fluency and reading skills. A total of 120 participants were interviewed about their experiences with reading and administered standardized reading and reading-related assessments. Speech fluency and the criterion for stuttering were based on the interview. About 18.3% of the sample met the criterion for stuttering. ASRs who stutter (ASRs-S) and ASRs who do not stutter (ASRs-NS) did not differ in their reading and reading-related skills. ASRs-S had higher rates of negative correlations between reading and reading-related skills compared with ASRs-NS. Correlation patterns between performance on standardized assessments point to higher rates of uneven skills or dissociations in ASRs-S. These findings may have implications for the assessment and instruction for ASRs.

Latent Class Analysis Reveals Distinct Groups Based on Executive Function and Socioemotional Traits, Developmental Conditions, and Stuttering: A Population Study

A growing body of research has reported associations between weaker Executive Functions (EF), the set capacities that are needed to manage and allocate one's cognitive resources during cognitively challenging activities and various neurodevelopmental conditions, including stuttering. The majority of this research has been based on variable-centered approaches, which have the potential to obscure within-population heterogeneity. Person-centered analyses are essential to understanding multifactorial disorders where relationships between indicators have been elusive, such as stuttering. The current study addressed gaps in the literature by using latent class analysis (LCA), a person-centered approach, to identify homogenous subgroups within the National Health Interview Survey (2004-2018) publicly available data set. Using this exploratory approach, we examined the hypothesis that there exist distinct classes (or subgroups) of children based on parent reports of EF, Socioemotional (SE) traits, developmental atypicality, and stuttering. Our analyses revealed distinct subgroups with substantially different likelihoods of parent-reported stuttering behaviors and developmental atypicality. For children with both EF and SE difficulties, the likelihood of parental report of stuttering and atypical development was even higher, in fact this likelihood (of stuttering and not-typically developing) was highest among all subgroups. In contrast, children without difficulties were the least likely to be reported with stuttering or not-typically developing. Our findings are consistent with theoretical frameworks for stuttering, which cite EF as a crucial component in the disorder. Additionally, our findings suggest within-population heterogeneity among children with EF difficulties and, specifically, EF and SE heterogeneity among children who stutter.

Competitive state of movements during planning predicts sequence performance

Humans can learn and produce skilled movement sequences from memory, yet the nature of sequence planning is not well understood. Previous computational and neurophysiological work suggests that movements in a sequence are planned as parallel graded activations and selected for output through competition. However, the relevance of this planning pattern to sequence production fluency and accuracy, as opposed to the temporal structure of sequences, is unclear. To resolve this question, we assessed the relative availability of constituent movements behaviorally during the preparation of motor sequences from memory. In three separate multisession experiments, healthy participants were trained to retrieve and produce four-element finger press sequences with particular timing according to an abstract sequence cue. We evaluated reaction time (RT) and error rate as markers of movement availability to constituent movement probes. Our results demonstrate that longer preparation time produces more pronounced differences in availability between adjacent sequence elements, whereas no effect was found for sequence speed or temporal grouping. Further, participants with larger position-dependent differences in movement availability tended to initiate correct sequences faster and with a higher temporal accuracy. Our results suggest that competitive preactivation is established gradually during sequence planning and predicts sequence skill, rather than the temporal structure of the motor sequence.NEW & NOTEWORTHY Sequence planning is an integral part of motor sequence control. Here, we demonstrate that the competitive state of sequential movements during sequence planning can be read out behaviorally through movement probes. We show that position-dependent differences in movement availability during planning reflect sequence preparedness and skill but not the timing of the planned sequence. Behavioral access to the preparatory state of movements may serve as a marker of sequence planning capacity.

Lexical Planning in People Who Stutter: A Defect in Lexical Encoding or the Planning Scope?

Developmental stuttering is a widely discussed speech fluency disorder. Research on its mechanism has focused on an atypical interface between the planning (PLAN) and execution (EX) processes, known collectively as the EXPLAN model. However, it remains unclear how this atypical interface influences people who stutter. A straightforward assumption is that stuttering speakers adopt a smaller scope of speech planning, whereas a defect in word retrieval can be confounding. To shed light on this issue, we took the semantic blocking effect as an index to examine lexical planning in word and phrase production. In Experiment 1, for word production, pictures from the same semantic category were combined to form homogeneous blocks, and pictures from different categories were combined to form heterogeneous blocks. A typical effect of semantic blocking showing longer naming latencies for homogeneous blocks than heterogeneous ones was observed for both stuttering and fluent speakers. However, this effect was smaller for stuttering speakers, when it was subject to lexical defects in stuttering. In Experiment 2, for a conjoined noun phrase production task, the pictures referring to the first noun were manipulated into homogeneous and heterogeneous conditions. The semantic blocking effect was also much smaller for stuttering speakers, indicating a smaller scope of lexical planning. Therefore, the results provided more evidence in support of the EXPLAN model and indicated that a smaller scope of lexical planning rather than lexical defects causes the atypical interface for stuttering. Moreover, a comparison between these two tasks showed that the study findings have implications for syntactic defects in stuttering.

Associations between stuttering, comorbid conditions and executive function in children: a population-based study

Background

The aim of this study was to investigate the relationship between executive function (EF), stuttering, and comorbidity by examining children who stutter (CWS) and children who do not stutter (CWNS) with and without comorbid conditions. Data from the National Health Interview Survey were used to examine behavioral manifestations of EF, such as inattention and self-regulation, in CWS and CWNS.

Methods

The sample included 2258 CWS (girls = 638, boys = 1620), and 117,725 CWNS (girls = 57,512; boys = 60,213). EF, and the presence of stuttering and comorbid conditions were based on parent report. Descriptive statistics were used to describe the distribution of stuttering and comorbidity across group and sex. Regression analyses were to determine the effects of stuttering and comorbidity on EF, and the relationship between EF and socioemotional competence.

Results

Results point to weaker EF in CWS compared to CWNS. Also, having comorbid conditions was also associated with weaker EF. CWS with comorbidity showed the weakest EF compared to CWNS with and without comorbidity, and CWS without comorbidity. Children with stronger EF showed higher socioemotional competence. A majority (60.32%) of CWS had at least one other comorbid condition in addition to stuttering. Boys who stutter were more likely to have comorbid conditions compared to girls who stutter.

Conclusion

Present findings suggest that comorbidity is a common feature in CWS. Stuttering and comorbid conditions negatively impact EF.

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

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.

End-word dysfluencies in young children: a clinical report

OBJECTIVE

We report on 12 children with end-word dysfluencies (EWDs). Our aim was to document this little-reported type of dysfluency and to develop a possible explanation for them and how they relate to developmental stuttering.

METHOD

Audio recordings were made for 9 of the 12 children in the study. The EWDs were identified by consensus of two specialist speech pathologists and confirmed on acoustic displays. A segment of participant 1's speech was transcribed, including phonetic transcription of EWDs.

RESULTS

The EWDs typically consisted of repetitions of the nucleus and/or the coda. However, there were also some EWDs that consisted of fixed postures on the nucleus (when in final position) or coda. We also report on the infrequent occurrence of broken words. Ten of the 12 children also stuttered, with 9 of them coming from four families, each with a history of stuttering.

CONCLUSION

This study indicates that EWDs may be more prevalent than previously thought, but they may go largely unnoticed due to their perceptually fleeting nature. The hypothesis was developed that EWDs be regarded as another type of developmental dysfluency, along with stuttering and cluttering. Ideas for further research are suggested.

Computational modeling of stuttering caused by impairments in a basal ganglia thalamo-cortical circuit involved in syllable selection and initiation

Atypical white-matter integrity and elevated dopamine levels have been reported for individuals who stutter. We investigated how such abnormalities may lead to speech dysfluencies due to their effects on a syllable-sequencing circuit that consists of basal ganglia (BG), thalamus, and left ventral premotor cortex (vPMC). "Neurally impaired" versions of the neurocomputational speech production model GODIVA were utilized to test two hypotheses: (1) that white-matter abnormalities disturb the circuit via corticostriatal projections carrying copies of executed motor commands and (2) that dopaminergic abnormalities disturb the circuit via the striatum. Simulation results support both hypotheses: in both scenarios, the neural abnormalities delay readout of the next syllable's motor program, leading to dysfluency. The results also account for brain imaging findings during dysfluent speech. It is concluded that each of the two abnormality types can cause stuttering moments, probably by affecting the same BG-thalamus-vPMC circuit.

Classification of types of stuttering symptoms based on brain activity

Among the non-fluencies seen in speech, some are more typical (MT) of stuttering speakers, whereas others are less typical (LT) and are common to both stuttering and fluent speakers. No neuroimaging work has evaluated the neural basis for grouping these symptom types. Another long-debated issue is which type (LT, MT) whole-word repetitions (WWR) should be placed in. In this study, a sentence completion task was performed by twenty stuttering patients who were scanned using an event-related design. This task elicited stuttering in these patients. Each stuttered trial from each patient was sorted into the MT or LT types with WWR put aside. Pattern classification was employed to train a patient-specific single trial model to automatically classify each trial as MT or LT using the corresponding fMRI data. This model was then validated by using test data that were independent of the training data. In a subsequent analysis, the classification model, just established, was used to determine which type the WWR should be placed in. The results showed that the LT and the MT could be separated with high accuracy based on their brain activity. The brain regions that made most contribution to the separation of the types were: the left inferior frontal cortex and bilateral precuneus, both of which showed higher activity in the MT than in the LT; and the left putamen and right cerebellum which showed the opposite activity pattern. The results also showed that the brain activity for WWR was more similar to that of the LT and fluent speech than to that of the MT. These findings provide a neurological basis for separating the MT and the LT types, and support the widely-used MT/LT symptom grouping scheme. In addition, WWR play a similar role as the LT, and thus should be placed in the LT type.

Behavioral effects arising from the neural substrates for atypical planning and execution of word production in stuttering

This article reports on an fMRI study that examined the neural bases of atypical planning and execution processes involved in stuttering (Lu et al., 2010). In the study, twelve stuttering speakers and 12 controls named pictures which required single-syllable, multi-syllable, or repeated-syllable word responses, in the scanner. The factors associated with planning and execution were: (1) number of syllable-sized motor programs; and (2) syllable size and onset complexity. Structural equation modeling revealed two parallel neural circuits (the basal ganglia-inferior frontal gyrus, premotor area circuit and the cerebellum-premotor area circuit). These were involved in atypical planning and execution processes in stuttering, respectively. The interface between planning and execution in stuttering involved the angular gyrus. This article discusses the relevance of these findings to behavioral theories that also propose separate planning and execution mechanisms behind stuttering.

Chiari malformation type III and results of surgery: a clinical study: report of eight surgically treated cases and review of the literature

BACKGROUND

The characteristics of Chiari malformation type III and its treatment are evaluated in this study. Radiological and surgical findings were correlated and the benefits of the therapy are discussed.

METHODS

Eight patients (6 males, 2 females) with Chiari malformation type III were studied. All patients underwent surgery to remove encephalocele along with neural tissue and to repair the dura and the skin. Associated pathologies such as hydrocephalus, tethered cord syndrome and syringomyelia were also surgically treated. Follow-up was based on the evaluation of postoperative motor and mental development, as well as on magnetic resonance imaging findings.

RESULTS

Ventriculoperitoneal shunt malfunction in 2 patients was the only surgical complication. One patient died 10 days after the operation, 7 patients survived, and the outcome of 2 patients was quite poor because of severe mental retardation and neurological deficits at the beginning. In the remaining patients, motor and mental development was normal, and the neurological outcome was satisfactory.

CONCLUSION

Surgery in the newborn period, initial severity of neurological deficits, the presence of intermittent apnoea, delayed treatment of hydrocephalus and the amount of neuronal tissue within the excised encephalocele were determined as unfavourable prognostic factors for the outcome. If the appropriate surgical procedure is done at the right time, the outcome of the Chiari malformation type III patient can be satisfactory with a low mortality rate.