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.

Do Not Cut Off Your Tail: A Mega-Analysis of Responses to Auditory Perturbation Experiments.

PURPOSE: The practice of removing "following" responses from speech perturbation analyses is increasingly common, despite no clear evidence as to whether these responses represent a unique response type. This study aimed to determine if the distribution of responses to auditory perturbation paradigms represents a bimodal distribution, consisting of two distinct response types, or a unimodal distribution. METHOD: This mega-analysis pooled data from 22 previous studies to examine the distribution and magnitude of responses to auditory perturbations across four tasks: adaptive pitch, adaptive formant, reflexive pitch, and reflexive formant. Data included at least 150 unique participants for each task, with studies comprising younger adult, older adult, and Parkinson's disease populations. A Silverman's unimodality test followed by a smoothed bootstrap resampling technique was performed for each task to evaluate the number of modes in each distribution. Wilcoxon signed-ranks tests were also performed for each distribution to confirm significant compensation in response to the perturbation. RESULTS: Modality analyses were not significant (p > .05) for any group or task, indicating unimodal distributions. Our analyses also confirmed compensatory reflexive responses to pitch and formant perturbations across all groups, as well as adaptive responses to sustained formant perturbations. However, analyses of sustained pitch perturbations only revealed evidence of adaptation in studies with younger adults. CONCLUSION: The demonstration of a clear unimodal distribution across all tasks suggests that following responses do not represent a distinct response pattern, but rather the tail of a unimodal distribution. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.24282676.

Improvements in Speech of Children with Apraxia: The Efficacy of Treatment for Establishing Motor Program Organization (TEMPOSM).

Purpose: This study investigated the efficacy of Treatment for Establishing Motor Program Organization (TEMPOSM) in childhood apraxia of speech (CAS).Method: A mixed between- and within-participant design with multiple baselines across participants and behaviors was used to examine acquisition, generalization, and maintenance of skills. TEMPOSM was administered in four one-hour sessions a week over a four-week period for eleven participants (ages 5 to 8), allocated to either an immediate treatment group or a wait-list control group. Acoustic and perceptual variables were measured at baseline, immediate post-treatment, and one-month post-treatment.Results: Children demonstrated significant improvements in specific acoustic measures of segmentation and lexical stress, as well as perceptual measures of fluency, lexical stress, and speech-sound accuracy. Treatment and generalization effects were maintained one-month post-treatment with generalization to untreated stimuli.Conclusion: TEMPOSM was efficacious in improving segmental and suprasegmental impairments in the speech of children with CAS.

Modelling speech motor programming and apraxia of speech in the DIVA/GODIVA neurocomputational framework.

BACKGROUND: The Directions Into Velocities of Articulators (DIVA) model and its partner, the Gradient Order DIVA (GODIVA) model, provide neurobiologically grounded, computational accounts of speech motor control and motor sequencing, with applications for the study and treatment of neurological motor speech disorders. AIMS: In this review, we provide an overview of the DIVA and GODIVA models and how they explain the interface between phonological and motor planning systems to build on previous models and provide a mechanistic accounting of apraxia of speech (AOS), a disorder of speech motor programming. MAIN CONTRIBUTION: Combined, the DIVA and GODIVA models account for both the segmental and suprasegmental features that define AOS via damage to (i) a speech sound map, hypothesized to reside in left ventral premotor cortex, (ii) a phonological content buffer hypothesized to reside in left posterior inferior frontal sulcus, and/or (iii) the axonal projections between these regions. This account is in line with a large body of behavioural work, and it unifies several prior theoretical accounts of AOS. CONCLUSIONS: The DIVA and GODIVA models provide an integrated framework for the generation and testing of both behavioural and neuroimaging hypotheses about the underlying neural mechanisms responsible for motor programming in typical speakers and in speakers with AOS.

Neural substrates of verbal repetition deficits in primary progressive aphasia.

In this cross-sectional study, we examined the relationship between cortical thickness and performance on several verbal repetition tasks in a cohort of patients with primary progressive aphasia in order to test predictions generated by theoretical accounts of phonological working memory that predict phonological content buffers in left posterior inferior frontal sulcus and supramarginal gyrus. Cortical surfaces were reconstructed from magnetic resonance imaging scans from 42 participants diagnosed with primary progressive aphasia. Cortical thickness was measured in a set of anatomical regions spanning the entire cerebral cortex. Correlation analyses were performed between cortical thickness and average score across three phonological working memory-related tasks: the Repetition sub-test from the Western Aphasia Battery, a forward digit span task, and a backward digit span task. Significant correlations were found between average working memory score across tasks and cortical thickness in left supramarginal gyrus and left posterior inferior frontal sulcus, in support of prior theoretical accounts of phonological working memory. Exploratory whole-brain correlation analyses performed for each of the three behavioural tasks individually revealed a distinct set of positively correlated regions for each task. Comparison of cortical thickness measures from different primary progressive aphasia sub-types to cortical thickness in age-matched controls further revealed unique patterns of atrophy in the different subtypes.

Integration of memory content in adults and children: Developmental differences in task conditions and functional consequences.

How separate yet related episodes of experience are associated in memory is a major question in cognitive science and cognitive neuroscience. Adults and children both integrate content acquired in separate episodes, yet they may do so under different task conditions. Neuroimaging studies suggest that adults integrate the contents of separate memory traces at encoding and thus without an explicit prompt; behavioral studies suggest that children do so only when specifically prompted. In the present research, we developed a novel paradigm to test integration of memory content using eye-gaze in an indirect (unprompted) test and self-derivation of new factual knowledge based on related facts in direct (open-ended and forced-choice) tests. To permit use of color images to accompany the stimuli, we developed a procedure for equating color images on 23 low-level properties that otherwise might control eye-gaze behavior. We used the paradigm with adults (Experiment 1) and 7- to 9-year-old children (Experiment 2). Both groups succeeded on the direct tests. Among adults, unprompted integration of memory content (in the indirect test) was apparent and supported open-ended self-derivation (in the direct test). Across trials, children did not show evidence of unprompted integration of memory content and performance during the unprompted indirect test did not support open-ended self-derivation; longer looking to target versus foil images during the indirect test was related to direct test performance under forced-choice conditions, however. The patterns indicate that adults and children engage the process of integration of memory content under different task conditions, and that when integration processes take place without an explicit prompt they have different functional consequences for adults and children. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Speech and Gesture Production Provide Unique Insights Into Young Children's Spatial Reasoning.

This study took a novel approach to understanding the role of language in spatial development by combining approaches from spatial language and gesture research. It analyzed forty-three 4.5- to 6-year-old's speech and gesture production during explanations of reasoning behind performance on Spatial Analogies and Children's Mental Transformation Tasks. Results showed that speech and gesture relevant for solving the trials (disambiguating correct choices) predicted spatial performance when controlling for age, gender, and spatial words and gestures produced. Children performed the spatial tasks well if they produced relevant information either verbally through speech or nonverbally through gesture. These results highlight the importance of not only focusing on concepts children can reference but also on how such concepts are used in spatial tasks.

Using eye-tracking to understand relations between visual attention and language in children's spatial skills.

Relations between children's spatial language and spatial skills raise questions regarding whether the effects are unique to language or reflect non-linguistic processes. Different paradigms provided mixed evidence: experimenter-provided language supports spatial performance more than visual cues; however, children's non-verbal attention predicts their spatial performance more than their language production. The current study used eye-tracking during spatial recall to compare effects of language versus visual cues. Four- to five-year-old children completed two tasks requiring memory for the location of a toy under one of four cups in an array of cups and landmarks after a 5 s delay and array rotation. Children first completed the baseline task with non-specific cues, followed by the cue-manipulation task with either language, visual, or non-specific cues provided by the experimenter. As in prior studies, language cues were most effective in facilitating recall. Children's visual attention was directed by both language and visual cues to support their recall. However, visual attention only partially mediated the effects of language: language supported recall above and beyond directing visual attention. These results indicate that visual attention supports spatial recall, but language has additional unique influences. This may result from language providing a more coherent or redundant code to visual information, or due to the pragmatic nature of language cueing relevance in ways visual cues do not. Additionally, differences across conditions may reflect more benefit from endogenous versus exogenous attentional control. Through using eye-tracking, this research provided new insights into processes by which language and visual attention influence children's spatial cognition.

Children's attention to task-relevant information accounts for relations between language and spatial cognition.

Children's spatial language reliably predicts their spatial skills, but the nature of this relation is a source of debate. This investigation examined whether the mechanisms accounting for such relations are specific to language use or reflect a domain-general mechanism of selective attention. Experiment 1 examined whether 4-year-olds' spatial skills were predicted by their selective attention or their adaptive language use. Children completed (a) an attention task assessing attention to task-relevant color, size, and location cues; (b) a description task assessing adaptive language use to describe scenes varying in color, size, and location; and (c) three spatial tasks. There was correspondence between the cue types that children attended to and produced across description and attention tasks. Adaptive language use was predicted by both children's attention and task-related language production, suggesting that selective attention underlies skills in using language adaptively. After controlling for age, gender, receptive vocabulary, and adaptive language use, spatial skills were predicted by children's selective attention. The attention score predicted variance in spatial performance previously accounted for by adaptive language use. Experiment 2 followed up on the attention task (Experiment 2a) and description task (Experiment 2b) from Experiment 1 to assess whether performance in the tasks related to selective attention or task-specific demands. Performance in Experiments 2a and 2b paralleled that in Experiment 1, suggesting that the effects in Experiment 1 reflected children's selective attention skills. These findings show that selective attention is a central factor supporting spatial skill development that could account for many effects previously attributed to children's language use.

Producing Spatial Words Is Not Enough: Understanding the Relation Between Language and Spatial Cognition.

Prior research has investigated the relation between children's language and spatial cognition by assessing the quantity of children's spatial word production, with limited attention to the context in which children use such words. This study tested whether 4-year-olds children's (N = 41, primarily white middle class) adaptive use of task-relevant language across contexts predicted their spatial skills. Children were presented with a spatial scene description task, four spatial tasks, and vocabulary assessments. Children's adaptive use of task-relevant language was more predictive of their spatial skills than demographic and language factors (e.g., quantity of spatial words produced). These findings identify new links between language and spatial cognition and highlight the importance of understanding the quality, not just quantity, of children's language use.

Developmental improvements in the resolution and capacity of visual working memory share a common source.

The nature of visual working memory (VWM) representations is currently a source of debate between characterizations as slot-like versus a flexibly-divided pool of resources. Recently, a dynamic neural field model has been proposed as an alternative account that focuses more on the processes by which VWM representations are formed, maintained, and used in service of behavior. This dynamic model has explained developmental increases in VWM capacity and resolution through strengthening excitatory and inhibitory connections. Simulations of developmental improvements in VWM resolution suggest that one important change is the accuracy of comparisons between items held in memory and new inputs. Thus, the ability to detect changes is a critical component of developmental improvements in VWM performance across tasks, leading to the prediction that capacity and resolution should correlate during childhood. Comparing 5- to 8-year-old children's performance across color discrimination and change detection tasks revealed the predicted correlation between estimates of VWM capacity and resolution, supporting the hypothesis that increasing connectivity underlies improvements in VWM during childhood. These results demonstrate the importance of formalizing the processes that support the use of VWM, rather than focusing solely on the nature of representations. We conclude by considering our results in the broader context of VWM development.

Language supports young children's use of spatial relations to remember locations.

Two experiments investigated the role of language in children's spatial recall performance. In particular, we assessed whether selecting an intrinsic reference frame could be improved through verbal encoding. Selecting an intrinsic reference frame requires remembering locations relative to nearby objects independent of one's body (egocentric) or distal environmental (allocentric) cues, and does not reliably occur in children under 5 years of age (Nardini, Burgess, Breckenridge, & Atkinson, 2006). The current studies tested the relation between spatial language and 4-year-olds' selection of an intrinsic reference frame in spatial recall. Experiment 1 showed that providing 4-year-olds with location-descriptive cues during (Exp. 1a) or before (Exp. 1b) the recall task improved performance both overall and specifically on trials relying most on an intrinsic reference frame. Additionally, children's recall performance was predicted by their verbal descriptions of the task space (Exp. 1a control condition). Non-verbally highlighting relations among objects during the recall task (Exp. 2) supported children's performance relative to the control condition, but significantly less than the location-descriptive cues. These results suggest that the ability to verbally represent relations is a potential mechanism that could account for developmental changes in the selection of an intrinsic reference frame during spatial recall.

Different developmental trajectories across feature types support a dynamic field model of visual working memory development.

Research on visual working memory has focused on characterizing the nature of capacity limits as "slots" or "resources" based almost exclusively on adults' performance with little consideration for developmental change. Here we argue that understanding how visual working memory develops can shed new light onto the nature of representations. We present an alternative model, the Dynamic Field Theory (DFT), which can capture effects that have been previously attributed either to "slot" or "resource" explanations. The DFT includes a specific developmental mechanism to account for improvements in both resolution and capacity of visual working memory throughout childhood. Here we show how development in the DFT can account for different capacity estimates across feature types (i.e., color and shape). The current paper tests this account by comparing children's (3, 5, and 7 years of age) performance across different feature types. Results showed that capacity for colors increased faster over development than capacity for shapes. A second experiment confirmed this difference across feature types within subjects, but also showed that the difference can be attenuated by testing memory for less familiar colors. Model simulations demonstrate how developmental changes in connectivity within the model-purportedly arising through experience-can capture differences across feature types.