Evidence for planning and motor subtypes of stuttering based on resting state functional connectivity

We tested the hypothesis, generated from the Gradient Order Directions Into Velocities of Articulators (GODIVA) model, that adults who stutter (AWS) may comprise subtypes based on differing connectivity within the cortico-basal ganglia planning or motor loop. Resting state functional connectivity from 91 AWS and 79 controls was measured for all GODIVA model connections. Based on a principal components analysis, two connections accounted for most of the connectivity variability in AWS: left thalamus - left posterior inferior frontal sulcus (planning loop component) and left supplementary motor area - left ventral premotor cortex (motor loop component). A k-means clustering algorithm using the two connections revealed three clusters of AWS. Cluster 1 was significantly different from controls in both connections; Cluster 2 was significantly different in only the planning loop; and Cluster 3 was significantly different in only the motor loop. These findings suggest the presence of planning and motor subtypes of stuttering.

Contemporary clinical conversations about stuttering: What does brain imaging research mean to clinicians?

PURPOSE

To discuss among neuroscientists and community speech-language pathologists what brain imaging research means to clinicians.

METHOD

Two university neuroscientists and two speech-language pathologists in private practice discussed the matter. Written conversational turns in an exchange were limited to 100 words each. When that written dialogue was concluded, each participant provided 200 words of final reflection about the matter.

RESULT

For now, neuroscience treatments are not available for clinicians to use. But sometime in the future, a critical mass of neuroscientists will likely produce such treatments. The neuroscientists expressed diverse views about the methods that might be used for that to occur.

CONCLUSION

Neuroscience does have practical clinical application at present and, in a way, that does not exclude a concurrent influence of the social model of disability. As such, the current practices of the clinicians are supported by basic neuroscience research.

Brain response to errors in children who stutter

PURPOSE

Heightened rates of social anxiety have been reported in adults who stutter (AWS), but it is unclear whether anxiety is heightened also in children who stutter (CWS). Objective neurophysiological responses such as the error-related negativity (ERN) have been associated with anxiety, and ERN was reported to be increased in AWS. In this study, we examined whether ERN and error positivity (Pe) are increased in CWS. We further characterized ERN associations with age and anxiety in CWS relative to children who do not stutter (CWNS).

METHODS

EEG data were recorded from twenty-four CWS and twenty-four matched CWNS aged 3-9 years as they performed a Go/No-Go task. Parent-reported anxiety, and child-reported speech-associated attitude measures were collected. Linear regression models tested the effects of age, group, and their interaction, and the effects of anxiety, group, and their interaction on ERN and Pe.

RESULTS

Contrary to expectations, no ERN or Pe difference were observed between CWS and CWNS. However, larger ERN amplitudes were associated with older age in CWS but not CWNS, suggesting altered development of the error monitoring system in CWS. Association of Pe with anxiety also differed between groups: smaller Pe amplitudes were associated with higher level of parent-reported child anxiety in CWNS but not in CWS. Neither anxiety nor self-reported communication attitude differed between groups.

CONCLUSIONS

Brain responses to errors were overall comparable between CWS and CWNS. However, CWS differed in how error monitoring responses varied with age and with anxiety levels. More research is warranted to examine how these factors contribute to persistent stuttering.

Knowns and unknowns about the neurobiology of stuttering

Stuttering occurs in early childhood during a dynamic phase of brain and behavioral development. The latest studies examining children at ages close to this critical developmental period have identified early brain alterations that are most likely linked to stuttering, while spontaneous recovery appears related to increased inter-area connectivity. By contrast, therapy-driven improvement in adults is associated with a functional reorganization within and beyond the speech network. The etiology of stuttering, however, remains enigmatic. This Unsolved Mystery highlights critical questions and points to neuroimaging findings that could inspire future research to uncover how genetics, interacting neural hierarchies, social context, and reward circuitry contribute to the many facets of stuttering.

Neural oscillatory activity and connectivity in children who stutter during a non-speech motor task

BACKGROUND

Neural motor control rests on the dynamic interaction of cortical and subcortical regions, which is reflected in the modulation of oscillatory activity and connectivity in multiple frequency bands. Motor control is thought to be compromised in developmental stuttering, particularly involving circuits in the left hemisphere that support speech, movement initiation, and timing control. However, to date, evidence comes from adult studies, with a limited understanding of motor processes in childhood, closer to the onset of stuttering.

METHODS

We investigated the neural control of movement initiation in children who stutter and children who do not stutter by evaluating transient changes in EEG oscillatory activity (power, phase locking to button press) and connectivity (phase synchronization) during a simple button press motor task. We compared temporal changes in these oscillatory dynamics between the left and right hemispheres and between children who stutter and children who do not stutter, using mixed-model analysis of variance.

RESULTS

We found reduced modulation of left hemisphere oscillatory power, phase locking to button press and phase connectivity in children who stutter compared to children who do not stutter, consistent with previous findings of dysfunction within the left sensorimotor circuits. Interhemispheric connectivity was weaker at lower frequencies (delta, theta) and stronger in the beta band in children who stutter than in children who do not stutter.

CONCLUSIONS

Taken together, these findings indicate weaker engagement of the contralateral left motor network in children who stutter even during low-demand non-speech tasks, and suggest that the right hemisphere might be recruited to support sensorimotor processing in childhood stuttering. Differences in oscillatory dynamics occurred despite comparable task performance between groups, indicating that an altered balance of cortical activity might be a core aspect of stuttering, observable during normal motor behavior.

A comparison of structural morphometry in children and adults with persistent developmental stuttering

This cross-sectional study aimed to differentiate earlier occurring neuroanatomical differences that may reflect core deficits in stuttering versus changes associated with a longer duration of stuttering by analysing structural morphometry in a large sample of children and adults who stutter and age-matched controls. Whole-brain T1-weighted structural scans were obtained from 166 individuals who stutter (74 children, 92 adults; ages 3-58) and 191 controls (92 children, 99 adults; ages 3-53) from eight prior studies in our laboratories. Mean size and gyrification measures were extracted using FreeSurfer software for each cortical region of interest. FreeSurfer software was also used to generate subcortical volumes for regions in the automatic subcortical segmentation. For cortical analyses, separate ANOVA analyses of size (surface area, cortical thickness) and gyrification (local gyrification index) measures were conducted to test for a main effect of diagnosis (stuttering, control) and the interaction of diagnosis-group with age-group (children, adults) across cortical regions. Cortical analyses were first conducted across a set of regions that comprise the speech network and then in a second whole-brain analysis. Next, separate ANOVA analyses of volume were conducted across subcortical regions in each hemisphere. False discovery rate corrections were applied for all analyses. Additionally, we tested for correlations between structural morphometry and stuttering severity. Analyses revealed thinner cortex in children who stutter compared with controls in several key speech-planning regions, with significant correlations between cortical thickness and stuttering severity. These differences in cortical size were not present in adults who stutter, who instead showed reduced gyrification in the right inferior frontal gyrus. Findings suggest that early cortical anomalies in key speech planning regions may be associated with stuttering onset. Persistent stuttering into adulthood may result from network-level dysfunction instead of focal differences in cortical morphometry. Adults who stutter may also have a more heterogeneous neural presentation than children who stutter due to their unique lived experiences.

Brain activity during the preparation and production of spontaneous speech in children with persistent stuttering

Speech production forms the basis for human verbal communication. Though fluent speech production is effortless and automatic for most people, it is disrupted in speakers who stutter, who experience difficulties especially during spontaneous speech and at utterance onsets. Brain areas comprising the basal ganglia thalamocortical (BGTC) motor loop have been a focus of interest in the context of stuttering, given this circuit's critical role in initiating and sequencing connected speech. Despite the importance of better understanding the role of the BGTC motor loop in supporting overt, spontaneous speech production, capturing brain activity during speech has been challenging to date, due to fMRI artifacts associated with severe head motions during speech production. Here, using an advanced technique that removes speech-related artifacts from fMRI signals, we examined brain activity occurring immediately before, and during, overt spontaneous speech production in 22 children with persistent stuttering (CWS) and 18 children who do not stutter (controls) in the 5-to-12-year age range. Brain activity during speech production was compared in two conditions: spontaneous speech (i.e., requiring language formulation) and automatic speech (i.e., overlearned word sequences). Compared to controls, CWS exhibited significantly reduced left premotor activation during spontaneous speech production but not during automatic speech. Moreover, CWS showed an age-related reduction in left putamen and thalamus activation during speech preparation. These results provide further evidence that stuttering is associated with functional deficits in the BGTC motor loop, which are exacerbated during spontaneous speech production.

Brain developmental trajectories associated with childhood stuttering persistence and recovery

Stuttering is a neurodevelopmental disorder affecting 5-8 % of preschool-age children, continuing into adulthood in 1 % of the population. The neural mechanisms underlying persistence and recovery from stuttering remain unclear and little information exists on neurodevelopmental anomalies in children who stutter (CWS) during preschool age, when stuttering symptoms typically first emerge. Here we present findings from the largest longitudinal study of childhood stuttering to date, comparing children with persistent stuttering (pCWS) and those who later recovered from stuttering (rCWS) with age-matched fluent peers, to examine the developmental trajectories of both gray matter volume (GMV) and white matter volume (WMV) using voxel-based morphometry. A total of 470 MRI scans were analyzed from 95 CWS (72 pCWS and 23 rCWS) and 95 fluent peers between 3 and 12 years of age. We examined overall group and group by age interactions in GMV and WMV in preschool age (3-5 years old) and school age (6-12 years old) CWS and controls, controlling for sex, IQ, intracranial volume, and socioeconomic status. The results provide broad support for a possible basal ganglia-thalamocortical (BGTC) network deficit starting in the earliest phases of the disorder and point to normalization or compensation of earlier occurring structural changes associated with stuttering recovery.

Dissecting structural connectivity of the left and right inferior frontal cortex in children who stutter

Inferior frontal cortex pars opercularis (IFCop) features a distinct cerebral dominance and vast functional heterogeneity. Left and right IFCop are implicated in developmental stuttering. Weak left IFCop connections and divergent connectivity of hyperactive right IFCop regions have been related to impeded speech. Here, we reanalyzed diffusion magnetic resonance imaging data from 83 children (41 stuttering). We generated connection probability maps of functionally segregated area 44 parcels and calculated hemisphere-wise analyses of variance. Children who stutter showed reduced connectivity of executive, rostral-motor, and caudal-motor corticostriatal projections from the left IFCop. We discuss this finding in the context of tracing studies from the macaque area 44, which leads to the need to reconsider current models of speech motor control. Unlike the left, the right IFCop revealed increased connectivity of the inferior posterior ventral parcel and decreased connectivity of the posterior dorsal parcel with the anterior insula, particularly in stuttering boys. This divergent connectivity pattern in young children adds to the debate on potential core deficits in stuttering and challenges the theory that right hemisphere differences might exclusively indicate compensatory changes that evolve from lifelong exposure. Instead, early right prefrontal connectivity differences may reflect additional brain signatures of aberrant cognition-emotion-action influencing speech motor control.

Combined Cognitive Training and Transcranial Direct Current Stimulation in Neuropsychiatric Disorders: A Systematic Review and Meta-analysis

BACKGROUND

Treatments for cognitive dysfunction in neuropsychiatric conditions are urgently needed. Cognitive training and transcranial direct current stimulation (tDCS) hold promise, and there is growing interest in combined or multimodal treatments, though studies to date have had small samples and inconsistent results.

METHODS

A systematic review and meta-analysis was completed. Retained studies included cognitive training combined with active or sham tDCS in a neuropsychiatric population and reported a posttreatment cognitive outcome. Meta-analyses included effect sizes comparing cognitive training plus active tDCS and cognitive training plus sham tDCS in 5 cognitive domains. Risk of bias in included studies and across studies was explored.

RESULTS

Fifteen studies were included: 10 in neurodegenerative disorders and 5 in psychiatric disorders (n = 629). There were several tDCS montages, though two-thirds of studies placed the anode over the left dorsolateral prefrontal cortex. A wide variety of cognitive training types and outcome measures were reported. There was a small, statistically significant effect of combined treatment on measures of attention/working memory, as well as small and non-statistically significant effects favoring combined treatment on global cognition and language. There was no evidence of bias in individual studies but some evidence of nonreporting or small-study bias across studies.

CONCLUSIONS

These results may provide preliminary support for the efficacy of combined cognitive training and tDCS on measures of attention/working memory. More data are needed, particularly via studies that explicitly align the cognitive ability of interest, stimulation target, training type, and outcome measures.

Auditory rhythm discrimination in adults who stutter: An fMRI study

Rhythm perception deficits have been linked to neurodevelopmental disorders affecting speech and language. Children who stutter have shown poorer rhythm discrimination and attenuated functional connectivity in rhythm-related brain areas, which may negatively impact timing control required for speech. It is unclear whether adults who stutter (AWS), who are likely to have acquired compensatory adaptations in response to rhythm processing/timing deficits, are similarly affected. We compared rhythm discrimination in AWS and controls (total n = 36) during fMRI in two matched conditions: simple rhythms that consistently reinforced a periodic beat, and complex rhythms that did not (requiring greater reliance on internal timing). Consistent with an internal beat deficit hypothesis, behavioral results showed poorer complex rhythm discrimination for AWS than controls. In AWS, greater stuttering severity was associated with poorer rhythm discrimination. AWS showed increased activity within beat-based timing regions and increased functional connectivity between putamen and cerebellum (supporting interval-based timing) for simple rhythms.

Neural activity during solo and choral reading: A functional magnetic resonance imaging study of overt continuous speech production in adults who stutter

Previous neuroimaging investigations of overt speech production in adults who stutter (AWS) found increased motor and decreased auditory activity compared to controls. Activity in the auditory cortex is heightened, however, under fluency-inducing conditions in which AWS temporarily become fluent while synchronizing their speech with an external rhythm, such as a metronome or another speaker. These findings suggest that stuttering is associated with disrupted auditory motor integration. Technical challenges in acquiring neuroimaging data during continuous overt speech production have limited experimental paradigms to short or covert speech tasks. Such paradigms are not ideal, as stuttering primarily occurs during longer speaking tasks. To address this gap, we used a validated spatial ICA technique designed to address speech movement artifacts during functional magnetic resonance imaging (fMRI) scanning. We compared brain activity and functional connectivity of the left auditory cortex during continuous speech production in two conditions: solo (stutter-prone) and choral (fluency-inducing) reading tasks. Overall, brain activity differences in AWS relative to controls in the two conditions were similar, showing expected patterns of hyperactivity in premotor/motor regions but underactivity in auditory regions. Functional connectivity of the left auditory cortex (STG) showed that within the AWS group there was increased correlated activity with the right insula and inferior frontal area during choral speech. The AWS also exhibited heightened connectivity between left STG and key regions of the default mode network (DMN) during solo speech. These findings indicate possible interference by the DMN during natural, stuttering-prone speech in AWS, and that enhanced coordination between auditory and motor regions may support fluent speech.

Tract profiles of the cerebellar peduncles in children who stutter

Cerebellar-cortical loops comprise critical neural circuitry that supports self-initiated movements and motor adjustments in response to perceived errors, functions that are affected in stuttering. It is unknown whether structural aspects of cerebellar circuitry are affected in stuttering, particularly in children close to symptom onset. Here we examined white matter diffusivity characteristics of the three cerebellar peduncles (CPs) based on diffusion MRI (dMRI) data collected from 41 children who stutter (CWS) and 42 controls in the 3-11 years range. We hypothesized that CWS would exhibit decreased fractional anisotropy (FA) in the right CPs given the contralateral connectivity of the cerebellar-cortical loops and past reports of structural differences in left cortical areas in stuttering speakers. Automatic Fiber Quantification (AFQ) was used to track and segment cerebellar white matter pathways and to extract diffusivity measures. We found significant group differences for FA in the right inferior CP (ICP) only: controls showed significantly higher FA in the right ventral ICP compared to CWS, controlling for age, sex, and verbal IQ. Furthermore, FA of right ICP was negatively correlated with stuttering frequency in CWS. These results suggest an early developmental difference in the right ICP for CWS compared to age-matched peers, which may indicate an alteration in error processing, a function previously linked to the ICP. Lower FA here may impact error monitoring and sensory input processing to guide motor corrections. Further longitudinal investigations in children may provide additional insights into how CP development links to stuttering persistence and recovery.

Charting brain growth and aging at high spatial precision

Defining reference models for population variation, and the ability to study individual deviations is essential for understanding inter-individual variability and its relation to the onset and progression of medical conditions. In this work, we assembled a reference cohort of neuroimaging data from 82 sites (N=58,836; ages 2-100) and used normative modeling to characterize lifespan trajectories of cortical thickness and subcortical volume. Models are validated against a manually quality checked subset (N=24,354) and we provide an interface for transferring to new data sources. We showcase the clinical value by applying the models to a transdiagnostic psychiatric sample (N=1985), showing they can be used to quantify variability underlying multiple disorders whilst also refining case-control inferences. These models will be augmented with additional samples and imaging modalities as they become available. This provides a common reference platform to bind results from different studies and ultimately paves the way for personalized clinical decision-making.

Predicting Persistent Developmental Stuttering Using a Cumulative Risk Approach

PURPOSE

The purpose of this study was to explore how well a cumulative risk approach, based on empirically supported predictive factors, predicts whether a young child who stutters is likely to develop persistent developmental stuttering. In a cumulative risk approach, the number of predictive factors indicating a child is at risk to develop persistent stuttering is evaluated, and a greater number of indicators of risk are hypothesized to confer greater risk of persistent stuttering.

METHOD

We combined extant data on 3- to 5-year-old children who stutter from two longitudinal studies to identify cutoff values for continuous predictive factors (e.g., speech and language skills, age at onset, time since onset, stuttering frequency) and, in combination with binary predictors (e.g., sex, family history of stuttering), used all-subsets regression and receiver operating characteristic curves to compare the predictive validity of different combinations of 10 risk factors. The optimal combination of predictive factors and the odds of a child developing persistent stuttering based on an increasing number of factors were calculated.

RESULTS

Based on 67 children who stutter (i.e., 44 persisting and 23 recovered) with relatively strong speech-language skills, the predictive factor model that yielded the best predictive validity was based on time since onset (≥ 19 months), speech sound skills (≤ 115 standard score), expressive language skills (≤ 106 standard score), and stuttering severity (≥ 17 Stuttering Severity Instrument total score). When the presence of at least two predictive factors was used to confer elevated risk to develop persistent stuttering, the model yielded 93% sensitivity and 65% specificity. As a child presented with a greater number of these four risk factors, the odds for persistent stuttering increased.

CONCLUSIONS

Findings support the use of a cumulative risk approach and the predictive utility of assessing multiple domains when evaluating a child's risk of developing persistent stuttering. Clinical implications and future directions are discussed.

Developmental Factors That Predict Head Movement During Resting-State Functional Magnetic Resonance Imaging in 3-7-Year-Old Stuttering and Non-stuttering Children

Early childhood marks a period of dynamic neurocognitive development. Preschool-age coincides with the onset of many childhood disorders and is a developmental period that is frequently studied to determine markers of neurodevelopmental disorders. Magnetic resonance imaging (MRI) is often used to explore typical brain development and the neural bases of neurodevelopmental disorders. However, acquiring high-quality MRI data in young children is challenging. The enclosed space and loud sounds can trigger unease and cause excessive head movement. A better understanding of potential factors that predict successful MRI acquisition would increase chances of collecting useable data in children with and without neurodevelopmental disorders. We investigated whether age, sex, stuttering status, and childhood temperament as measured using the Child Behavioral Questionnaire, could predict movement extent during resting-state functional MRI (rs-fMRI) in 76 children aged 3–7 years, including 42 children who stutter (CWS). We found that age, sex, and temperament factors could predict motion during rs-fMRI scans. The CWS were not found to differ significantly from controls in temperament or head movement during scanning. Sex and age were significant predictors of movement. However, age was no longer a significant predictor when temperament, specifically effortful control, was considered. Controlling for age, boys with higher effortful control scores moved less during rs-fMRI procedures. Additionally, boys who showed higher negative affectivity showed a trend for greater movement. Considering temperament factors in addition to age and sex may help predict the success of acquiring useable rs-fMRI (and likely general brain MRI) data in young children in MR neuroimaging.

Association Between Gray Matter Volume Variations and Energy Utilization in the Brain: Implications for Developmental Stuttering

Purpose The biological mechanisms underlying developmental stuttering remain unclear. In a previous investigation, we showed that there is significant spatial correspondence between regional gray matter structural anomalies and the expression of genes linked to energy metabolism. In the current study, we sought to further examine the relationship between structural anomalies in the brain in children with persistent stuttering and brain regional energy metabolism. Method High-resolution structural MRI scans were acquired from 26 persistent stuttering and 44 typically developing children. Voxel-based morphometry was used to quantify the between-group gray matter volume (GMV) differences across the whole brain. Group differences in GMV were then compared with published values for the pattern of glucose metabolism measured via F18 fluorodeoxyglucose uptake in the brains of 29 healthy volunteers using positron emission tomography. Results A significant positive correlation between GMV differences and F18 fluorodeoxyglucose uptake was found in the left hemisphere (ρ = .36, p < .01), where speech-motor and language processing are typically localized. No such correlation was observed in the right hemisphere (ρ = .05, p = .70). Conclusions Corroborating our previous gene expression studies, the results of the current study suggest a potential connection between energy metabolism and stuttering. Brain regions with high energy utilization may be particularly vulnerable to anatomical changes associated with stuttering. Such changes may be further exacerbated when there are sharp increases in brain energy utilization, which coincides with the developmental period of rapid speech/language acquisition and the onset of stuttering during childhood. Supplemental Material https://doi.org/10.23641/asha.14110454.

Linking Lysosomal Enzyme Targeting Genes and Energy Metabolism with Altered Gray Matter Volume in Children with Persistent Stuttering

Developmental stuttering is a childhood onset neurodevelopmental disorder with an unclear etiology. Subtle changes in brain structure and function are present in both children and adults who stutter. It is a highly heritable disorder, and 12-20% of stuttering cases may carry a mutation in one of four genes involved in intracellular trafficking. To better understand the relationship between genetics and neuroanatomical changes, we used gene expression data from the Allen Institute for Brain Science and voxel-based morphometry to investigate the spatial correspondence between gene expression patterns and differences in gray matter volume between children with persistent stuttering (n = 26, and 87 scans) and their fluent peers (n = 44, and 139 scans). We found that the expression patterns of two stuttering-related genes (GNPTG and NAGPA) from the Allen Institute data exhibited a strong positive spatial correlation with the magnitude of between-group gray matter volume differences. Additional gene set enrichment analyses revealed that genes whose expression was highly correlated with the gray matter volume differences were enriched for glycolysis and oxidative metabolism in mitochondria. Because our current study did not examine the participants' genomes, these results cannot establish the direct association between genetic mutations and gray matter volume differences in stuttering. However, our results support further study of the involvement of lysosomal enzyme targeting genes, as well as energy metabolism in stuttering. Future studies assessing variations of these genes in the participants' genomes may lead to increased understanding of the biological mechanisms of the observed spatial relationship between gene expression and gray matter volume.

Lexical diversity and lexical skills in children who stutter

PURPOSE

Numerous "small N" studies of language ability in children who stutter have produced differing conclusions. We combined test and spontaneous language data from a large cohort of children who stutter (CWS) and typically fluent peers, gathered from independent laboratories across the US, to appraise a variety of lexical measures.

METHOD

Standardized receptive and expressive vocabulary test data and spontaneous language samples from 99 pairs of CWS (ages 25-100 months), and age-, gender-, and SES-matched children who do not stutter (CWNS) were compared. Language sample transcripts were analyzed with four measures of lexical diversity. Correlations between lexical diversity measures and expressive vocabulary scores were also calculated.

RESULTS

On standardized tests of both receptive and expressive vocabulary, there were significant differences between CWS and CWNS. In contrast, on spontaneous language measures of lexical diversity, CWS did not differ in their lexical diversity, across analyses, compared to CWNS. Three of the four lexical diversity analyses, MATTR, VocD, and NDW, were significantly correlated with each other.

CONCLUSIONS

We were able to confirm prior findings of relative disadvantage on standardized vocabulary tests for a very large sample of well-matched CWS. However, spontaneous language measures of lexical diversity did not distinguish the groups. This relative weakness in CWS may emerge from task differences: CWS are free to encode their own spontaneous utterances but must comply with explicit lexical prompts in standardized testing situations.

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.

A Simple 3-Parameter Model for Examining Adaptation in Speech and Voice Production

Sensorimotor adaptation experiments are commonly used to examine motor learning behavior and to uncover information about the underlying control mechanisms of many motor behaviors, including speech production. In the speech and voice domains, aspects of the acoustic signal are shifted/perturbed over time via auditory feedback manipulations. In response, speakers alter their production in the opposite direction of the shift so that their perceived production is closer to what they intended. This process relies on a combination of feedback and feedforward control mechanisms that are difficult to disentangle. The current study describes and tests a simple 3-parameter mathematical model that quantifies the relative contribution of feedback and feedforward control mechanisms to sensorimotor adaptation. The model is a simplified version of the DIVA model, an adaptive neural network model of speech motor control. The three fitting parameters of SimpleDIVA are associated with the three key subsystems involved in speech motor control, namely auditory feedback control, somatosensory feedback control, and feedforward control. The model is tested through computer simulations that identify optimal model fits to six existing sensorimotor adaptation datasets. We show its utility in (1) interpreting the results of adaptation experiments involving the first and second formant frequencies as well as fundamental frequency; (2) assessing the effects of masking noise in adaptation paradigms; (3) fitting more than one perturbation dimension simultaneously; (4) examining sensorimotor adaptation at different timepoints in the production signal; and (5) quantitatively predicting responses in one experiment using parameters derived from another experiment. The model simulations produce excellent fits to real data across different types of perturbations and experimental paradigms (mean correlation between data and model fits across all six studies = 0.95 ± 0.02). The model parameters provide a mechanistic explanation for the behavioral responses to the adaptation paradigm that are not readily available from the behavioral responses alone. Overall, SimpleDIVA offers new insights into speech and voice motor control and has the potential to inform future directions of speech rehabilitation research in disordered populations. Simulation software, including an easy-to-use graphical user interface, is publicly available to facilitate the use of the model in future studies.

Neurofilament-lysosomal genetic intersections in the cortical network of stuttering

The neurobiological underpinnings of stuttering, a speech disorder characterized by disrupted speech fluency, remain unclear. While recent developments in the field have afforded researchers the ability to pinpoint several genetic profiles associated with stuttering, how these specific genetic backgrounds impact neuronal circuits and how they generate or facilitate the emergence of stuttered speech remains unknown. In this study, we identified the large-scale cortical network that characterizes stuttering using functional connectivity MRI and graph theory. We performed a spatial similarity analysis that examines whether the topology of the stuttering cortical network intersects with genetic expression levels of previously reported genes for stuttering from the protein-coding transcriptome data of the Allen Human Brain Atlas. We found that GNPTG - a gene involved in the mannose-6-phosphate lysosomal targeting pathways - was significantly co-localized with the stuttering cortical network. An enrichment analysis demonstrated that the genes identified with the stuttering cortical network shared a significantly overrepresented biological functionality of Neurofilament Cytoskeleton Organization (NEFH, NEFL and INA). The relationship between lysosomal pathways, cytoskeleton organization, and stuttering, was investigated by comparing the genetic interactome between GNPTG and the neurofilament genes implicated in the current study. We found that genes of the interactome network, including CDK5, SNCA, and ACTB, act as functional links between lysosomal and neurofilament genes. These findings support the notion that stuttering is due to a lysosomal dysfunction, which has deleterious effects on the neurofilament organization of the speech neuronal circuits. They help to elucidate the intriguing, unsolved link between lysosomal mutations and the presence of stuttering.

Topically applied treatments for external genital warts in nonimmunocompromised patients: a systematic review and network meta-analysis

Selecting a topical treatment from among the numerous topical agents for external genital warts remains challenging without clear evidence. Our aim was to evaluate comparatively the efficacy and safety of topical agents for external genital warts using a network meta-analysis. We included all randomized controlled trials that evaluated any topically applied treatment for external genital warts. Using the R package netmeta, network meta-analyses were performed with a frequentist approach. We identified 41 relevant studies comprising 6371 patients. Among conventional agents, podophyllotoxin 0·5% solution (odds ratio 1·94, 95% confidence interval 1·02-3·71) was significantly more efficacious than imiquimod 5% cream for lesion clearance; however, it was associated with a higher overall adverse event rate. Sinecatechins 15% ointment (odds ratio 0·21, 95% confidence interval 0·12-0·34) was significantly less efficacious than imiquimod 5% cream. Idoxuridine, polyhexamethylene biguanide, cidofovir and SB206 showed comparable therapeutic efficacies with conventional therapies. None of the treatments were significantly different from each other with respect to recurrence, patients with severe adverse events, or patients who withdrew because of treatment-related adverse events. Conventional modalities were efficacious and well tolerated, although each of them had their advantages and disadvantages. Additional efficacy and safety studies are warranted for unconventional agents.

Stuttering Severity Modulates Effects of Non-invasive Brain Stimulation in Adults Who Stutter

Stuttering is a neurodevelopmental disorder that manifests as frequent disruptions in the flow of speech, affecting 1% of adults. Treatments are limited to behavioral interventions with variable success and high relapse rates, particularly in adults. However, even in severe cases, fluency can be temporarily induced during conditions in which the speaker synchronizes his speech with external rhythmic cues, such as when reading in unison (choral speech) or with a metronome. Non-invasive neuromodulation techniques such as transcranial direct current stimulation (tDCS) have shown promise in augmenting the effects of behavioral treatment during motor and speech/language rehabilitation, but only one study to date has examined behavioral modulatory effects of tDCS in the context of stuttering. Using high-definition (HD)-tDCS electrodes, which improves focality of stimulation relative to conventional tDCS, we investigated the effects of tDCS on speech fluency and brain activation in 14 adults who stutter (AWS). Either anodal or sham stimulation was delivered on separate days over left supplementary motor area (SMA). During stimulation, participants read aloud in sync with a metronome. Measures of speech fluency and brain activity functional magnetic resonance imaging (fMRI) were collected before and after stimulation. No significant differences in brain activity or speech fluency were found when comparing active and sham stimulation. However, stuttering severity significantly modulated the effect of stimulation: active stimulation attenuated the atypically strong association between stuttering severity and right thalamocortical network activity, especially in more severe speakers. These preliminary results warrant additional research into potential application of HD-tDCS to modulate speech motor networks to enhance fluency in stuttering.

Neuroanatomical Correlates of Childhood Stuttering: MRI Indices of White and Gray Matter Development That Differentiate Persistence Versus Recovery

Purpose We review two recent neuroanatomical studies of children who stutter (CWS), one that examines white matter integrity and the other that focuses on cortical gray matter morphology. In both studies, we sought to examine differences between children whose stuttering persists ("persistent"), children who recovered from stuttering ("recovered"), and their nonstuttering peers ("controls"). Method Both of the reviewed studies use data from a large pediatric sample spanning preschool- to school-age children (3-10 years old at initial testing). Study 1 focused on surface-based measures of cortical size (thickness) and shape (gyrification) using structural magnetic resonance imaging, whereas Study 2 utilized diffusion tensor imaging to examine white matter integrity. Results In both studies, the main difference that emerged between CWS and fluent peers encompassed left hemisphere speech motor areas that are interconnected via the arcuate fasciculus. In the case of white matter integrity, the temporoparietal junction and posterior superior temporal gyrus, both connected via the left arcuate fasciculus, and regions along the corpus callosum that contain fibers connecting bilateral motor regions were significantly decreased in white matter integrity in CWS compared to controls. In the morphometric study, children who would go on to have persistent stuttering specifically had lower cortical thickness in ventral motor and premotor areas of the left hemisphere. Conclusion These results point to aberrant development of cortical areas involved in integrating sensory feedback with speech movements in CWS and differences in interhemispheric connectivity between the two motor cortices. Furthermore, developmental trajectories in these areas seem to diverge between persistent and recovered cases.

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.

Stuttering and gray matter morphometry: A population-based neuroimaging study in young children

Stuttering is a developmental speech disorder originating in early childhood. We aimed to replicate the association of stuttering and structural morphometry using a large, population-based prospective cohort, the Generation R Study, and explore the neurobiological mechanism of stuttering in children. Twenty-six children with a history of stuttering and 489 fluent speaking peers (ages 6-9) were included in the MRI sub-study. Cortical and subcortical regions of interest were analyzed using linear regression models. Compared to fluent speakers, children with a history of stuttering had less gray matter volume in the left inferior frontal gyrus and supplementary motor area. Exploratory surface-based brain analysis showed thinner cortex in the left inferior frontal gyrus, and in bilateral frontal and parietal areas. These findings corroborate previous studies that reported aberrant brain morphometry in speech motor and auditory regions in children who stutter. Future research is needed to explore the causal nature of this association.

Functional and Neuroanatomical Bases of Developmental Stuttering: Current Insights

Affecting 5% of all preschool-aged children and 1% of the general population, developmental stuttering-also called childhood-onset fluency disorder-is a complex, multifactorial neurodevelopmental disorder characterized by frequent disruption of the fluent flow of speech. Over the past two decades, neuroimaging studies of both children and adults who stutter have begun to provide significant insights into the neurobiological bases of stuttering. This review highlights convergent findings from this body of literature with a focus on functional and structural neuroimaging results that are supported by theoretically driven neurocomputational models of speech production. Updated views on possible mechanisms of stuttering onset and persistence, and perspectives on promising areas for future research into the mechanisms of stuttering, are discussed.

A systematic literature review of sex differences in childhood language and brain development

The extent of sex differences in childhood language development is unclear. We conducted a systematic literature review synthesizing results from studies examining sex differences in brain structure and function relevant to language development during childhood. We searched PubMed and Scopus databases, and this returned a total of 46 published studies meeting criteria for inclusion that directly examined sex differences in brain development relevant to language function in children. The results indicate that: (a) sex differences in brain structure or function do not necessarily lead to differences in language task performance; (b) evidence for sex differences in brain and language development are limited; (c) when present, sex differences often interact with a variety of factors such as age and task. Overall, the magnitude of sexual dimorphism of brain developmental trajectories associated with language is not as significant as previously thought. Sex differences were found, however, in studies employing tighter age ranges. This suggests that sex differences may be more prominent during certain developmental stages but are negligible in other stages, likely due to different rates of maturation between the sexes. More research is needed to improve our understanding of how sex differences may arise due to the influence of sex hormones and developmental stages, and how these differences may lead to differences in various language task performance. These studies are expected to provide normative information that may be used in studies examining neurodevelopmental disorders that frequently affect more males than females, and also often affect language development.

Anomalous network architecture of the resting brain in children who stutter

PURPOSE

We combined a large longitudinal neuroimaging dataset that includes children who do and do not stutter and a whole-brain network analysis in order to examine the intra- and inter-network connectivity changes associated with stuttering. Additionally, we asked whether whole brain connectivity patterns observed at the initial year of scanning could predict persistent stuttering in later years.

METHODS

A total of 224 high-quality resting state fMRI scans collected from 84 children (42 stuttering, 42 controls) were entered into an independent component analysis (ICA), yielding a number of distinct network connectivity maps ("components") as well as expression scores for each component that quantified the degree to which it is expressed for each child. These expression scores were compared between stuttering and control groups' first scans. In a second analysis, we examined whether the components that were most predictive of stuttering status also predicted persistence in stuttering.

RESULTS

Stuttering status, as well as stuttering persistence, were associated with aberrant network connectivity involving the default mode network and its connectivity with attention, somatomotor, and frontoparietal networks. The results suggest developmental alterations in the balance of integration and segregation of large-scale neural networks that support proficient task performance including fluent speech motor control.

CONCLUSIONS

This study supports the view that stuttering is a complex neurodevelopmental disorder and provides comprehensive brain network maps that substantiate past theories emphasizing the importance of considering situational, emotional, attentional and linguistic factors in explaining the basis for stuttering onset, persistence, and recovery.

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 expected 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 auditory 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.

Neural activity associated with rhythmicity of song in juvenile male and female zebra finches

Rhythm is an important aspect of both human speech and birdsong. Adult zebra finches show increased neural activity following exposure to arrhythmic compared to rhythmic song in regions similar to the mammalian auditory association cortex and amygdala. This pattern may indicate that birds are detecting errors in the arrhythmic song relative to their learned song template or to more general expectations of song structure. Here we exposed juvenile zebra finches to natural conspecific song (rhythmic) or song with altered inter-syllable intervals (arrhythmic) prior to or during template formation, or afterward as males are matching vocal production to a memorized song template (sensorimotor integration). Before template formation, expression of the immediate early gene ZENK was increased in the caudomedial nidopallium (NCM) of birds exposed to rhythmic relative to arrhythmic song. During template formation, ZENK expression was increased in the caudomedial mesopallium (CMM) of birds exposed to arrhythmic relative to rhythmic song. These results suggest that the youngest birds may be predisposed to respond to a more natural stimulus, and a template may be required for arrhythmic song to elicit increased neural activity. It also appears that functional development across the brain regions investigated continues to maturity.

ZENK induction in the zebra finch brain by song: Relationship to hemisphere, rhythm, oestradiol and sex

Oestradiol is abundant in the zebra finch auditory forebrain and has the capacity to modulate neural responses to auditory stimuli with specificity as a result of both hemisphere and sex. Arrhythmic song induces greater ZENK expression than rhythmic song in the caudomedial nidopallium (NCM), caudomedial mesopallium (CMM) and nucleus taeniae (Tn) of adult zebra finches. The increases in the auditory regions (i.e. NCM and CMM) may result from detection of errors in the arrhythmic song relative to the learned template. In the present study, zebra finches were treated with oestradiol, the aromatase inhibitor fadrozole or a control and then exposed to rhythmic or arrhythmic song to assess the effect of oestradiol availability on neural responses to auditory rhythms. ZENK mRNA was significantly greater in the left hemisphere within the NCM, CMM and Tn. Main effects of sex were detected in both auditory regions, with increased ZENK in males in the NCM and in females in the CMM. In the CMM, an effect of hormone treatment also existed. Although no pairwise comparison was statistically significant, the pattern suggested greater ZENK expression in control compared to both fadrozole- and oestradiol-treated birds. In the NCM, an interaction between sex and hormone treatment suggested that the sex effect was restricted to control animals. An additional interaction in the NCM among sex, stimulus rhythmicity and hemisphere indicated that the strongest effect of laterality was present in males exposed to arrhythmic song. The hormone effects suggest that an optimal level of oestradiol may exist for processing rhythmicity of auditory stimuli. The overall pattern for left lateralisation parallels the left lateralisation of language processing in humans and may suggest that this hemisphere is specialised for processing conspecific vocalisations. The reversed sex differences in the NCM and CMM suggest that males and females differentially rely on components of the auditory forebrain for processing conspecific song.

Social and Cognitive Impressions of Adults Who Do and Do Not Stutter Based on Listeners' Perceptions of Read-Speech Samples

Stuttering is a neurodevelopmental disorder characterized by frequent and involuntary disruptions during speech production. Adults who stutter are often subject to negative perceptions. The present study examined whether negative social and cognitive impressions are formed when listening to speech, even without any knowledge about the speaker. Two experiments were conducted in which naïve participants were asked to listen to and provide ratings on samples of read speech produced by adults who stutter and typically-speaking adults without knowledge about the individuals who produced the speech. In both experiments, listeners rated speaker cognitive ability, likeability, anxiety, as well as a number of speech characteristics that included fluency, naturalness, intelligibility, the likelihood the speaker had a speech-and-language disorder (Experiment 1 only), rate and volume (both Experiments 1 and 2). The speech of adults who stutter was perceived to be less fluent, natural, intelligible, and to be slower and louder than the speech of typical adults. Adults who stutter were also perceived to have lower cognitive ability, to be less likeable and to be more anxious than the typical adult speakers. Relations between speech characteristics and social and cognitive impressions were found, independent of whether or not the speaker stuttered (i.e., they were found for both adults who stutter and typically-speaking adults) and did not depend on being cued that some of the speakers may have had a speech-language impairment.

White matter developmental trajectories associated with persistence and recovery of childhood stuttering

Stuttering affects the fundamental human ability of fluent speech production, and can have a significant negative impact on an individual's psychosocial development. While the disorder affects about 5% of all preschool children, approximately 80% of them recover naturally within a few years of stuttering onset. The pathophysiology and neuroanatomical development trajectories associated with persistence and recovery of stuttering are still largely unknown. Here, the first mixed longitudinal diffusion tensor imaging (DTI) study of childhood stuttering has been reported. A total of 195 high quality DTI scans from 35 children who stutter (CWS) and 43 controls between 3 and 12 years of age were acquired, with an average of three scans per child, each collected approximately a year apart. Fractional anisotropy (FA), a measure reflecting white matter structural coherence, was analyzed voxel-wise to examine group and age-related differences using a linear mixed-effects (LME) model. Results showed that CWS exhibited decreased FA relative to controls in the left arcuate fasciculus, underlying the inferior parietal and posterior temporal areas, and the mid body of corpus callosum. Further, white matter developmental trajectories reflecting growth rate of these tract regions differentiated children with persistent stuttering from those who recovered from stuttering. Specifically, a reduction in FA growth rate (i.e., slower FA growth with age) in persistent children relative to fluent controls in the left arcuate fasciculus and corpus callosum was found, which was not evident in recovered children. These findings provide first glimpses into the possible neural mechanisms of onset, persistence, and recovery of childhood stuttering. Hum Brain Mapp 38:3345-3359, 2017. © 2017 Wiley Periodicals, Inc.

Relation between functional connectivity and rhythm discrimination in children who do and do not stutter

Our ability to perceive and produce rhythmic patterns in the environment supports fundamental human capacities ranging from music and language processing to the coordination of action. This article considers whether spontaneous correlated brain activity within a basal ganglia-thalamocortical (rhythm) network is associated with individual differences in auditory rhythm discrimination. Moreover, do children who stutter with demonstrated deficits in rhythm perception have weaker links between rhythm network functional connectivity and rhythm discrimination? All children in the study underwent a resting-state fMRI session, from which functional connectivity measures within the rhythm network were extracted from spontaneous brain activity. In a separate session, the same children completed an auditory rhythm-discrimination task, where behavioral performance was assessed using signal detection analysis. We hypothesized that in typically developing children, rhythm network functional connectivity would be associated with behavioral performance on the rhythm discrimination task, but that this relationship would be attenuated in children who stutter. Results supported our hypotheses, lending strong support for the view that (1) children who stutter have weaker rhythm network connectivity and (2) the lack of a relation between rhythm network connectivity and rhythm discrimination in children who stutter may be an important contributing factor to the etiology of stuttering.

Dissociations among linguistic, cognitive, and auditory-motor neuroanatomical domains in children who stutter

The onset of developmental stuttering typically occurs between 2 to 4 years of age, coinciding with a period of rapid development in speech, language, motor and cognitive domains. Previous studies have reported generally poorer performance and uneven, or "dissociated" development across speech and language domains in children who stutter (CWS) relative to children who do not stutter (CWNS) (Anderson, Pellowski, & Conture, 2005). The aim of this study was to replicate and expand previous findings by examining whether CWS exhibit dissociated development across speech-language, cognitive, and motor domains that are also reflected in measures of neuroanatomical development. Participants were 66CWS (23 females) and 53CWNS (26 females) ranging from 3 to 10 years. Standardized speech, language, cognitive, and motor skills measures, and fractional anisotropy (FA) values derived from diffusion tensor imaging from speech relevant "dorsal auditory" left perisylvian areas (Hickok & Poeppel, 2007) were analyzed using a correlation-based statistical procedure (Coulter, Anderson, & Conture, 2009) that quantified dissociations across domains. Overall, CWS scored consistently lower on speech, language, cognitive and motor measures, and exhibited dissociated development involving these same measures and white matter neuroanatomical indices relative to CWNS. Boys who stutter exhibited a greater number of dissociations compared to girls who stutter. Results suggest a subgroup of CWS may have incongruent development across multiple domains, and the resolution of this imbalance may be a factor in recovery from stuttering.

A combination of excimer laser treatment and topical tacrolimus is more effective in treating vitiligo than either therapy alone for the initial 6 months, but not thereafter

BACKGROUND

There are insufficient data on the long-term outcome of a combination therapy that comprises phototherapy and topical administration of tacrolimus.

AIM

To evaluate the clinical efficacy according to the duration of treatment and in vitro results of a combination therapy involving topical tacrolimus and an excimer laser in the treatment of vitiligo.

METHODS

In total, 276 patients with nonsegmental vitiligo were treated with an excimer laser twice weekly, or with tacrolimus ointment twice daily, or both. The melanin contents and levels of melanogenic enzymes were measured in cultured human melanocytes treated with tacrolimus and/or excimer laser.

RESULTS

After adjusting for potential confounders, the combination of tacrolimus plus excimer laser was significantly more effective than either tacrolimus or excimer laser alone (P < 0.001 and P < 0.01, respectively) for the first 6 months. However, this superiority was not observed after the initial 6 months of treatment. In vitro, the combination of tacrolimus plus excimer laser led to a higher level of melanogenesis than with either treatment alone.

CONCLUSIONS

A combination treatment with topical tacrolimus and an excimer laser may be useful as an induction therapy for up to 6 months, but continuation of this therapy for > 6 months might not provide a better final outcome than monotherapy.

Evidence for a rhythm perception deficit in children who stutter

Stuttering is a neurodevelopmental disorder that affects the timing and rhythmic flow of speech production. When speech is synchronized with an external rhythmic pacing signal (e.g., a metronome), even severe stuttering can be markedly alleviated, suggesting that people who stutter may have difficulty generating an internal rhythm to pace their speech. To investigate this possibility, children who stutter and typically-developing children (n=17 per group, aged 6-11 years) were compared in terms of their auditory rhythm discrimination abilities of simple and complex rhythms. Children who stutter showed worse rhythm discrimination than typically-developing children. These findings provide the first evidence of impaired rhythm perception in children who stutter, supporting the conclusion that developmental stuttering may be associated with a deficit in rhythm processing.

Secondary cutaneous lymphoma: comparative clinical features and survival outcome analysis of 106 cases according to lymphoma cell lineage

BACKGROUND

The relative frequency, clinical features and survival outcomes of secondary cutaneous lymphoma remain poorly understood.

OBJECTIVES

To determine the clinical characteristics and survival outcomes of secondary cutaneous lymphoma.

MATERIALS AND METHODS

The present retrospective cohort study included all 106 patients who presented with secondary cutaneous lymphoma. Patient medical records were reviewed to determine the clinical features, survival outcomes and prognostic factors. Survival outcomes were analysed by using the Kaplan-Meier method and comparisons between lymphoma cell lineages [T or natural killer (T-/NK)-cell vs. B-cell lymphoma] were performed using the log-rank test.

RESULTS

Secondary cutaneous lymphomas consisted of mature T-/NK-cell lymphomas (56%), mature B-cell lymphomas (35%), immature haematopoietic malignancies (8%) and Hodgkin lymphoma (1%). The T-/NK-cell lineage lymphoma cases were more likely to have multiple and disseminated skin lesions than the B-cell lineage lymphoma cases. The lymphoma cell lineage did not significantly influence survival outcomes. Patients who showed cutaneous involvement within 6 months of the initial diagnosis of primary disease had a poorer overall survival (OS) outcome than patients who developed cutaneous dissemination 6 or more months after the initial diagnosis (P < 0.001). Patients with disseminated skin lesions had a poorer OS than patients with localized skin lesions (P = 0.028). The two lymphoma cell lineages differed in terms of prognostic factors that influenced survival.

CONCLUSIONS

Skin lesion characteristics such as time point of appearance and extent affect the survival outcomes of secondary cutaneous lymphoma. Cell lineage did not influence survival outcomes but the two lineages are associated with different prognostic factors.

White matter neuroanatomical differences in young children who stutter

The ability to express thoughts through fluent speech production is a most human faculty, one that is often taken for granted. Stuttering, which disrupts the smooth flow of speech, affects 5% of preschool-age children and 1% of the general population, and can lead to significant communication difficulties and negative psychosocial consequences throughout one's lifetime. Despite the fact that symptom onset typically occurs during early childhood, few studies have yet examined the possible neural bases of developmental stuttering during childhood. Here we present a diffusion tensor imaging study that examined white matter measures reflecting neuroanatomical connectivity (fractional anisotropy) in 77 children [40 controls (20 females), 37 who stutter (16 females)] between 3 and 10 years of age. We asked whether previously reported anomalous white matter measures in adults and older children who stutter that were found primarily in major left hemisphere tracts (e.g. superior longitudinal fasciculus) are also present in younger children who stutter. All children exhibited normal speech, language, and cognitive development as assessed through a battery of assessments. The two groups were matched in chronological age and socioeconomic status. Voxel-wise whole brain comparisons using tract-based spatial statistics and region of interest analyses of fractional anisotropy were conducted to examine white matter changes associated with stuttering status, age, sex, and stuttering severity. Children who stutter exhibited significantly reduced fractional anisotropy relative to controls in white matter tracts that interconnect auditory and motor structures, corpus callosum, and in tracts interconnecting cortical and subcortical areas. In contrast to control subjects, fractional anisotropy changes with age were either stagnant or showed dissociated development among major perisylvian brain areas in children who stutter. These results provide first glimpses into the neuroanatomical bases of early childhood stuttering, and possible white matter developmental changes that may lead to recovery versus persistent stuttering. The white matter changes point to possible structural connectivity deficits in children who stutter, in interrelated neural circuits that enable skilled movement control through efficient sensorimotor integration and timing of movements.

Arrhythmic song exposure increases ZENK expression in auditory cortical areas and nucleus taeniae of the adult zebra Finch

Rhythm is important in the production of motor sequences such as speech and song. Deficits in rhythm processing have been implicated in human disorders that affect speech and language processing, including stuttering, autism, and dyslexia. Songbirds provide a tractable model for studying the neural underpinnings of rhythm processing due to parallels with humans in neural structures and vocal learning patterns. In this study, adult zebra finches were exposed to naturally rhythmic conspecific song or arrhythmic song. Immunohistochemistry for the immediate early gene ZENK was used to detect neural activation in response to these two types of stimuli. ZENK was increased in response to arrhythmic song in the auditory association cortex homologs, caudomedial nidopallium (NCM) and caudomedial mesopallium (CMM), and the avian amygdala, nucleus taeniae (Tn). CMM also had greater ZENK labeling in females than males. The increased neural activity in NCM and CMM during perception of arrhythmic stimuli parallels increased activity in the human auditory cortex following exposure to unexpected, or perturbed, auditory stimuli. These auditory areas may be detecting errors in arrhythmic song when comparing it to a stored template of how conspecific song is expected to sound. CMM may also be important for females in evaluating songs of potential mates. In the context of other research in songbirds, we suggest that the increased activity in Tn may be related to the value of song for assessing mate choice and bonding or it may be related to perception of arrhythmic song as aversive.

Research updates in neuroimaging studies of children who stutter

In the past two decades, neuroimaging investigations of stuttering have led to important discoveries of structural and functional brain differences in people who stutter, providing significant clues to the neurological basis of stuttering. One major limitation, however, has been that most studies so far have only examined adults who stutter, whose brain and behavior likely would have adopted compensatory reactions to their stuttering; these confounding factors have made interpretations of the findings difficult. Developmental stuttering is a neurodevelopmental condition, and like many other neurodevelopmental disorders, stuttering is associated with an early childhood onset of symptoms and greater incidence in males relative to females. More recent studies have begun to examine children who stutter using various neuroimaging techniques that allow examination of functional neuroanatomy and interaction of major brain areas that differentiate children who stutter compared with age-matched controls. In this article, I review these more recent neuroimaging investigations of children who stutter, in the context of what we know about typical brain development, neuroplasticity, and sex differences relevant to speech and language development. Although the picture is still far from complete, these studies have potential to provide information that can be used as early objective markers, or prognostic indicators, for persistent stuttering in the future. Furthermore, these studies are the first steps in finding potential neural targets for novel therapies that may involve modulating neuroplastic growth conducive to developing and maintaining fluent speech, which can be applied to treatment of young children who stutter.

A case of xanthoma disseminatum: evaluation and monitoring by 18F-fluorodeoxyglucose positron emission tomography/computed tomography

Xanthoma disseminatum (XD) is a rare benign histiocytic disorder with extensive mucocutaneous xanthomas that often involves other sites such as the central nervous system (CNS), respiratory tract and abdominal organs. Evaluation of the extent of disease is important because lesions in critical locations may increase morbidity and mortality. However, there are no well-established tools for the evaluation and monitoring of XD. Here, we report a case of XD in a 21-year-old male patient showing skin, mucous membrane, CNS and internal organ involvement. In this case, (18) F-fluorodeoxyglucose positron emission tomography/computed tomography was useful in detecting the extent of the disease and in estimating the therapeutic response.

Neural network connectivity differences in children who stutter

Affecting 1% of the general population, stuttering impairs the normally effortless process of speech production, which requires precise coordination of sequential movement occurring among the articulatory, respiratory, and resonance systems, all within millisecond time scales. Those afflicted experience frequent disfluencies during ongoing speech, often leading to negative psychosocial consequences. The aetiology of stuttering remains unclear; compared to other neurodevelopmental disorders, few studies to date have examined the neural bases of childhood stuttering. Here we report, for the first time, results from functional (resting state functional magnetic resonance imaging) and structural connectivity analyses (probabilistic tractography) of multimodal neuroimaging data examining neural networks in children who stutter. We examined how synchronized brain activity occurring among brain areas associated with speech production, and white matter tracts that interconnect them, differ in young children who stutter (aged 3-9 years) compared with age-matched peers. Results showed that children who stutter have attenuated connectivity in neural networks that support timing of self-paced movement control. The results suggest that auditory-motor and basal ganglia-thalamocortical networks develop differently in stuttering children, which may in turn affect speech planning and execution processes needed to achieve fluent speech motor control. These results provide important initial evidence of neurological differences in the early phases of symptom onset in children who stutter.

Corpus callosum morphology in children who stutter

Multiple studies have reported both functional and neuroanatomical differences between adults who stutter and their normally fluent peers. However, the reasons for these differences remain unclear although some developmental data suggest that structural brain differences may be present in school-age children who stutter. In the present study, the corpus callosum of children with persistent stuttering, children who recovered from stuttering and typically developing children between 9 and 12 years of age was compared to test if the presence of aberrant callosal morphology is implicated in this disorder. The total corpus callosum midsagittal area and area of each subsection consisting of the rostrum, anterior midbody, posterior midbody and splenium were measured using MIPAV (Medical Image Processing, Analysis, and Visualization). Voxel-based morphometry (VBM) was also used to compare white matter volume. No differences were detected in the corpus callosum area or white matter volume between children with persistent stuttering, children who recovered from stuttering and typically developing children. These results agree with dichotic listening studies that indicate children who stutter show the typical right ear advantage. Therefore, the neural reorganization across the midline shown in adults who stutter may be the result of long-term adaptations to persistent stuttering.

EDUCATIONAL OBJECTIVES

After reading this article, the reader will be able to: (1) summarize research findings on corpus callosum development; and (2) discuss the characteristics of corpus callosum anatomy in stuttering.

Using brain imaging to unravel the mysteries of stuttering

After many decades of attributing stuttering to causes ranging from childhood trauma to overly anxious personalities, scientists have used neuroimaging techniques to uncover measurable differences in the brain activity of people who stutter versus fluent speakers. But while researchers have made great strides in understanding stuttering in adults, the neural basis of stuttering in children largely remains a mystery. We do not yet know why up to 80 percent of children who stutter recover without intervention, nor do we know how to distinguish those who will recover without intervention from those who will not. However, recent findings support the idea that early intervention can alter or normalize brain function before stuttering-induced changes become hardwired.

Corpus callosum differences associated with persistent stuttering in adults

Recent studies have implicated anatomical differences in speech-relevant brain regions of adults who stutter (AWS) compared to normally fluent adults (NFA). The present study focused on the region of the corpus callosum (CC) which is involved in interhemispheric processing between the left and right cerebral hemispheres. Two-dimensional segmentation of area and voxel-based morphometry were used to evaluate the corpus callosum. Results revealed that the rostrum and anterior midbody of the CC were larger in AWS than NFA. In addition, the overall callosa area was larger in AWS than NFA. The group comparison of white matter volume showed a cluster of increased white matter volume predominantly encompassing the rostrum across the midline portion in AWS. These results potentially reflect anatomical changes associated with differences in the hemispheric distribution of language processes that have been reported previously in AWS.