Co-localisation of abnormal brain structure and function in specific language impairment

Implicit and Explicit Sequence Learning in Adults With Developmental Language Disorder

PURPOSE

Developmental language disorder (DLD) is a neurodevelopmental disorder that impacts approximately 7% of the population and is characterized by unexplained deficits in expressive and/or receptive components of language. A common procedural learning task, serial reaction time (SRT), has been used to develop models of the basis of DLD. However, paradigms involve differing levels of implicit and explicit learning during this task, muddying interpretations of the data. Here, we tested adults with DLD on implicit and explicit SRT tasks to better understand implicit and explicit procedural learning in this population. We hypothesized that adults with DLD would demonstrate reduced learning on only the implicit SRT task, as alternate explicit neural mechanisms could lead to equivalent performance on the explicit task.

METHOD

Fifty participants (25 with DLD and 25 with typical language) completed implicit and explicit SRT tasks, measuring their ability to learn visually presented 10-element sequences. Group differences were evaluated on sequence learning, error rates, and explicit recall of the sequence after learning.

RESULTS

Sequence learning was the same between the groups on both tasks. However, individuals with DLD showed increased errors and significantly worse recall of the explicitly learned sequence.

CONCLUSIONS

Results suggest that sequence learning may be intact in this population, while aspects of explicit learning and motoric responses are impaired. Results are interpreted in light of a neurobiological model of DLD.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.26210651.

Approaches to Measuring Language Lateralisation: An Exploratory Study Comparing Two fMRI Methods and Functional Transcranial Doppler Ultrasound

In this exploratory study we compare and contrast two methods for deriving a laterality index (LI) from functional magnetic resonance imaging (fMRI) data: the weighted bootstrapped mean from the LI Toolbox (toolbox method), and a novel method that uses subtraction of activations from homologous regions in left and right hemispheres to give an array of difference scores (mirror method). Data came from 31 individuals who had been selected to include a high proportion of people with atypical laterality when tested with functional transcranial Doppler ultrasound (fTCD). On two tasks, word generation and semantic matching, the mirror method generally gave better agreement with fTCD laterality than the toolbox method, both for individual regions of interest, and for a large region corresponding to the middle cerebral artery. LI estimates from this method had much smaller confidence intervals (CIs) than those from the toolbox method; with the mirror method, most participants were reliably lateralised to left or right, whereas with the toolbox method, a higher proportion were categorised as bilateral (i.e., the CI for the LI spanned zero). Reasons for discrepancies between fMRI methods are discussed: one issue is that the toolbox method averages the LI across a wide range of thresholds. Furthermore, examination of task-related t-statistic maps from the two hemispheres showed that language lateralisation is evident in regions characterised by deactivation, and so key information may be lost by ignoring voxel activations below zero, as is done with conventional estimates of the LI.

Differences in Cortical Surface Area in Developmental Language Disorder

Approximately 7% of children have developmental language disorder (DLD), a neurodevelopmental condition associated with persistent language learning difficulties without a known cause. Our understanding of the neurobiological basis of DLD is limited. Here, we used FreeSurfer to investigate cortical surface area and thickness in a large cohort of 156 children and adolescents aged 10-16 years with a range of language abilities, including 54 with DLD, 28 with a history of speech-language difficulties who did not meet criteria for DLD, and 74 age-matched controls with typical language development (TD). We also examined cortical asymmetries in DLD using an automated surface-based technique. Relative to the TD group, those with DLD showed smaller surface area bilaterally in the inferior frontal gyrus extending to the anterior insula, in the posterior temporal and ventral occipito-temporal cortex, and in portions of the anterior cingulate and superior frontal cortex. Analysis of the whole cohort using a language proficiency factor revealed that language ability correlated positively with surface area in similar regions. There were no differences in cortical thickness, nor in asymmetry of these cortical metrics between TD and DLD. This study highlights the importance of distinguishing between surface area and cortical thickness in investigating the brain basis of neurodevelopmental disorders and suggests the development of cortical surface area to be of importance to DLD. Future longitudinal studies are required to understand the developmental trajectory of these cortical differences in DLD and how they relate to language maturation.

Procedural auditory category learning is selectively disrupted in developmental language disorder

Speech communication depends on accurate perception and identification of speech sounds, which vary across talkers and word or sentence contexts. The ability to map this variable input onto discrete speech sound representations relies on categorization. Recent research and theoretical models implicate the procedural learning system in the ability to learn novel speech and non-speech categories. This connection is particularly intriguing because several language disorders that demonstrate linguistic impairments are proposed to stem from procedural learning and memory dysfunction. One such disorder, Developmental Language Disorder (DLD), affects 7.5% of children and persists into adulthood. While DLD is associated with general linguistic impairments, it is not yet clear how fundamental perceptual and cognitive processes supporting language are impacted, such as the ability to learn novel auditory categories. We examined auditory category learning in children with DLD and typically developed (TD) children using two well-matched nonspeech auditory category learning challenges to draw upon presumed procedural (information-integration) versus declarative (rule-based) learning systems. We observed impaired information-integration category learning and intact rule-based category learning in the DLD group. Quantitative model-based analyses revealed reduced use of, and slower shifting to, optimal procedural-based strategies in DLD and slower shifting to but similarly efficient use of optimal hypothesis-testing strategies. The dissociation is consistent with the Procedural Deficit Hypothesis of language disorders and supports the theoretical distinction of multiple category learning systems. These findings demonstrate that highly controlled experimental tasks assessing perceptual and cognitive abilities can relate to real-world challenges facing individuals with DLD in forming stable linguistic representations.

Beta Spectral Power during Passive Listening in Preschool Children with Specific Language Impairment

INTRODUCTION

Children with specific language impairment (SLI) have difficulties in different speech and language domains. Electrophysiological studies have documented that auditory processing in children with SLI is atypical and probably caused by delayed and abnormal auditory maturation. During the resting state, or different auditory tasks, children with SLI show low or high beta spectral power, which could be a clinical correlate for investigating brain rhythms.

METHODS

The aim of this study was to examine the electrophysiological cortical activity of the beta rhythm while listening to words and nonwords in children with SLI in comparison to typical development (TD) children. The participants were 50 children with SLI, aged 4 and 5 years, and 50 age matched TD children. The children were divided into two subgroups according to age: (1) children 4 years of age; (2) children 5 years of age.

RESULTS

The older group differed from the younger group in beta auditory processing, with increased values of beta spectral power in the right frontal, temporal, and parietal regions. In addition, children with SLI have higher beta spectral power than TD children in the bilateral temporal regions.

CONCLUSION

Complex beta auditory activation in TD and SLI children indicates the presence of early changes in functional brain connectivity.

The neuroanatomy of developmental language disorder: a systematic review and meta-analysis

Developmental language disorder (DLD) is a common neurodevelopmental disorder with adverse impacts that continue into adulthood. However, its neural bases remain unclear. Here we address this gap by systematically identifying and quantitatively synthesizing neuroanatomical studies of DLD using co-localization likelihood estimation, a recently developed neuroanatomical meta-analytic technique. Analyses of structural brain data (22 peer-reviewed papers, 577 participants) revealed highly consistent anomalies only in the basal ganglia (100% of participant groups in which this structure was examined, weighted by group sample sizes; 99.8% permutation-based likelihood the anomaly clustering was not due to chance). These anomalies were localized specifically to the anterior neostriatum (again 100% weighted proportion and 99.8% likelihood). As expected given the task dependence of activation, functional neuroimaging data (11 peer-reviewed papers, 414 participants) yielded less consistency, though anomalies again occurred primarily in the basal ganglia (79.0% and 95.1%). Multiple sensitivity analyses indicated that the patterns were robust. The meta-analyses elucidate the neuroanatomical signature of DLD, and implicate the basal ganglia in particular. The findings support the procedural circuit deficit hypothesis of DLD, have basic research and translational implications for the disorder, and advance our understanding of the neuroanatomy of language.

Hypomethylation of Wnt signaling regulator genes in developmental language disorder

Background: Developmental language disorder (DLD) is a neurodevelopmental disorder. Considering the pivotal role of epigenetics in neurodevelopment, we examined any altered DNA methylation between DLD and control subjects. Materials & methods: We looked into genome-wide methylation differences between DLD and control groups. The findings were validated by quantitative PCR (qPCR). Results: In the DLD group, differential methylation of CpG sites was observed in the Wnt signaling regulator genes APCDD1, AMOTL1, LRP5, MARK2, TMEM64, TRABD2B, VEPH1 and WNT2B. Hypomethylation of APCDD1, LRP5 and WNT2B was confirmed by qPCR. Conclusion: This is the first report associating Wnt signaling with DLD. The findings are relevant in the light of the essential role of Wnt in myelination, and of the altered myelination in DLD.

Beyond the language network: Associations between reading, receptive vocabulary, and grey matter volume in 10-year-olds

Most research on the neurostructural basis of language abilities in children stems from small samples and surface-based measures. To complement and expand the existent knowledge, we investigated associations between grey matter volume and language performance in a large sample of 9-to-11-year-old children, using data from the Adolescent Brain Cognitive Development (ABCD) Study (N = 1865) and an alternative measure of grey matter morphology. We estimated whole-brain grey matter volume for one half of the sample (N = 939) and tested for correlations with scores on a picture vocabulary and a letter and word reading test, with and without factoring in general intelligence and total grey matter volume as additional covariates. The initial analyses yielded correlations between grey matter in the right occipital fusiform gyrus, the right lingual gyrus, and the cerebellum for both vocabulary and reading. Employing the significant clusters from the first analyses as regions of interest in the second half of the cohort (N = 926) in correlational and multiple regression analyses suggests the cluster in the right occipital fusiform and lingual gyri to be most robust. Overall, the amount of variance explained by grey matter volume is limited and factoring in additional covariates paints an inconsistent picture. The present findings reinforce existent doubt with respect to explaining individual differences in reading and vocabulary performance based on unique contributions of macrostructural brain features.

Declarative Learning Mechanisms Support Declarative but Not Probabilistic Feedback-Based Learning in Children with Developmental Language Disorder (DLD)

Declarative and probabilistic feedback-based learning was evaluated in 8-12-year-old school-age children with developmental language disorder (DLD; n = 14) and age-matched children with typical development (TD; n = 15). Children performed a visual two-choice word-learning task and a visual probabilistic classification task while their electroencephalogram (EEG) was recorded non-invasively from the scalp. Behavioral measures of accuracy and response to feedback, and electrophysiological responses to feedback were collected and compared between the two groups. While behavioral data indicated poorer performance by children with DLD in both learning paradigms, and similar response patterns to positive and negative feedback, electrophysiological data highlighted processing patterns in the DLD group that differed by task. More specifically, in this group, feedback processing in the context of declarative learning, which is known to be dominated by the medial temporal lobe (MTL), was associated with enhanced N170, an event-related brain potential (ERP) associated with MTL activation. The N170 amplitude was found to be correlated with declarative task performance in the DLD group. During probabilistic learning, known to be governed by the striatal-based learning system, the feedback-related negativity (FRN) ERP, which is the product of the cortico-striatal circuit dominated feedback processing. Within the context of probabilistic learning, enhanced N170 was associated with poor learning in the TD group, suggesting that MTL activation during probabilistic learning disrupts learning. These results are interpreted within the context of a proposed feedback parity hypothesis suggesting that in children with DLD, the system that dominates learning (i.e., MTL during declarative learning and the striatum during probabilistic learning) dominates and supports feedback processing.

Bridging the Divide: Brain and Behavior in Developmental Language Disorder

Developmental language disorder (DLD) is a heterogenous neurodevelopmental disorder that affects a child's ability to comprehend and/or produce spoken and/or written language, yet it cannot be attributed to hearing loss or overt neurological damage. It is widely believed that some combination of genetic, biological, and environmental factors influences brain and language development in this population, but it has been difficult to bridge theoretical accounts of DLD with neuroimaging findings, due to heterogeneity in language impairment profiles across individuals and inconsistent neuroimaging findings. Therefore, the purpose of this overview is two-fold: (1) to summarize the neuroimaging literature (while drawing on findings from other language-impaired populations, where appropriate); and (2) to briefly review the theoretical accounts of language impairment patterns in DLD, with the goal of bridging the disparate findings. As will be demonstrated with this overview, the current state of the field suggests that children with DLD have atypical brain volume, laterality, and activation/connectivity patterns in key language regions that likely contribute to language difficulties. However, the precise nature of these differences and the underlying neural mechanisms contributing to them remain an open area of investigation.

Speech- and language-linked FOXP2 mutation targets protein motors in striatal neurons

Human speech and language are among the most complex motor and cognitive abilities. The discovery of a mutation in the transcription factor FOXP2 in KE family members with speech disturbances has been a landmark example of the genetic control of vocal communication in humans. Cellular mechanisms underlying this control have remained unclear. By leveraging FOXP2 mutation/deletion mouse models, we found that the KE family FOXP2R553H mutation directly disables intracellular dynein-dynactin 'protein motors' in the striatum by induction of a disruptive high level of dynactin1 that impairs TrkB endosome trafficking, microtubule dynamics, dendritic outgrowth and electrophysiological activity in striatal neurons alongside vocalization deficits. Dynactin1 knockdown in mice carrying FOXP2R553H mutations rescued these cellular abnormalities and improved vocalization. We suggest that FOXP2 controls vocal circuit formation by regulating protein motor homeostasis in striatal neurons, and that its disruption could contribute to the pathophysiology of FOXP2 mutation/deletion-associated speech disorders.

Microstructural Properties of the Cerebellar Peduncles in Children with Developmental Language Disorder

Children with developmental language disorder (DLD) struggle to learn their native language for no apparent reason. While research on the neurobiological underpinnings of the disorder has focused on the role of cortico-striatal systems, little is known about the role of the cerebellum in DLD. Cortico-cerebellar circuits might be involved in the disorder as they contribute to complex sensorimotor skill learning, including the acquisition of spoken language. Here, we used diffusion-weighted imaging data from 77 typically developing and 54 children with DLD and performed probabilistic tractography to identify the cerebellum's white matter tracts: the inferior, middle, and superior cerebellar peduncles. Children with DLD showed lower fractional anisotropy (FA) in the inferior cerebellar peduncles (ICP), fiber tracts that carry motor and sensory input via the inferior olive to the cerebellum. Lower FA in DLD was driven by lower axial diffusivity. Probing this further with more sophisticated modeling of diffusion data, we found higher orientation dispersion but no difference in neurite density in the ICP of DLD. Reduced FA is therefore unlikely to be reflecting microstructural differences in myelination in this tract, rather the organization of axons in these pathways is disrupted. ICP microstructure was not associated with language or motor coordination performance in our sample. We also found no differences in the middle and superior peduncles, the main pathways connecting the cerebellum with the cortex. To conclude, it is not cortico-cerebellar but atypical olivocerebellar white matter connections that characterize DLD and suggest the involvement of the olivocerebellar system in speech acquisition and development.

The contribution of theta and delta to feedback processing in children with developmental language disorder

PURPOSE

The study aimed at evaluating feedback processing at the electrophysiological level and its relation to learning in children with developmental language disorder (DLD) to further advance our understanding of the underlying neural mechanisms of feedback-based learning in children with this disorder.

METHOD

A feedback-based probabilistic learning task required children to classify novel cartoon animals into two categories that differ on five binary features, the probabilistic combination of which determined classification. The learning outcomes' variance in relation to time- and time-frequency measures of feedback processing were examined and compared between 20 children with developmental language disorder and 25 age-matched children with typical language development.

RESULTS

Children with developmental language disorder (DLD) performed poorer on the task when compared with their age-matched peers with typical language development (TD). The electrophysiological data in the time domain indicated no differences in the processing of positive and negative feedback among children with DLD. However, the time-frequency analysis revealed a strong theta activity in response to negative feedback in this group, suggesting an initial distinction between positive and negative feedback that was not captured by the ERP data. In the TD group, delta activity played a major role in shaping the FRN and P3a and was found to predict test performance. Delta did not contribute to the FRN and P3a in the DLD group. Additionally, theta and delta activities were not associated with the learning outcomes of children with DLD.

CONCLUSION

Theta activity, which is associated with the initial processing of feedback at the level of the anterior cingulate cortex, was detected in children with developmental language disorder (DLD) but was not associated with their learning outcomes. Delta activity, which is assumed to be generated by the striatum and to be linked to elaborate processing of outcomes and adjustment of future actions, contributed to processing and learning outcomes of children with typical language development but not of children with DLD. The results provide evidence for atypical striatum-based feedback processing in children with DLD.

Not only motor skill performance but also haptic function is impaired in children with developmental language disorder

BACKGROUND

Previous studies have found an association between motor immaturity and developmental language impairment in children. However, systematic investigations of somatosensory dysfunctions that might be linked to motor deficits in children with developmental language disorder (DLD) are lacking.

AIMS

Examined haptic perception and motor skills in school-age children with DLD and typically-developing (TD) children.

METHODS

Sixteen children with DLD and sixteen age-matched TD children performed a curvature detection task measuring haptic sensitivity and a curvature discrimination task measuring haptic acuity. The Movement Assessment Battery for Children, 2nd edition (MABC-2) was also conducted to evaluate children's motor ability.

RESULTS

The results revealed elevated thresholds of both haptic detection (67.5%) and haptic discrimination (67.9%) in the DLD group when compared to the TD group. In addition, the children with DLD performed significantly less well on the manual dexterity of MABC-2. Finally, a lower haptic acuity was associated with poorer manual dexterity scores of MABC-2.

CONCLUSIONS

This study demonstrates for the first time that not only motor skills, but also haptic function is altered in children with DLD. The observed association between manual dexterity and haptic acuity suggests a close relationship between haptic and motor skills in school-age children.

Functional near-infrared spectroscopy measures of neural activity in children with and without developmental language disorder during a working memory task

INTRODUCTION

Children with developmental language disorder (DLD) exhibit cognitive deficits that interfere with their ability to learn language. Little is known about the functional neuroanatomical differences between children developing typically (TD) and children with DLD.

METHODS

Using functional near-infrared spectroscopy, we recorded oxygenated hemoglobin (O₂ hb) concentration values associated with neural activity in children with and without DLD during an auditory N-back task that included 0-back, 1-back, and 2-back conditions. Analyses focused on the left dorsolateral prefrontal cortex (DLPFC) and left inferior parietal lobule (IPL). Multilevel models were constructed with accuracy, response time, and O₂ hb as outcome measures, with 0-back outcomes as fixed effects to control for sustained attention.

RESULTS

Children with DLD were significantly less accurate than their TD peers at both the 1-back and 2-back tasks, and they demonstrated slower response times during 2-back. In addition, children in the TD group demonstrated significantly greater sensitivity to increased task difficulty, showing increased O₂ hb to the IPL during 1-back and to the DLPFC during the 2-back, whereas the DLD group did not. A secondary analysis revealed that higher O₂ hb in the DLPFC predicted better task accuracy across groups.

CONCLUSION

When task difficulty increased, children with DLD failed to recruit the DLPFC for monitoring information and the IPL for processing information. Reduced memory capacity and reduced engagement likely contribute to the language learning difficulties of children with DLD.

Fetal temporal sulcus depth asymmetry has prognostic value for language development

In most humans, the superior temporal sulcus (STS) shows a rightward depth asymmetry. This asymmetry can not only be observed in adults, but is already recognizable in the fetal brain. As the STS lies adjacent to brain areas important for language, STS depth asymmetry may represent an anatomical marker for language abilities. This study investigated the prognostic value of STS depth asymmetry in healthy fetuses for later language abilities, language localization, and language-related white matter tracts. Less right lateralization of the fetal STS depth was significantly associated with better verbal abilities, with fetal STS depth asymmetry explaining more than 40% of variance in verbal skills 6-13 years later. Furthermore, less right fetal STS depth asymmetry correlated with increased left language localization during childhood. We hypothesize that earlier and/or more localized fetal development of the left temporal cortex is accompanied by an earlier development of the left STS and is favorable for early language learning. If the findings of this pilot study hold true in larger samples of healthy children and in different clinical populations, fetal STS asymmetry has the potential to become a diagnostic biomarker of the maturity and integrity of neural correlates of language.

Using Motor Tempi to Understand Rhythm and Grammatical Skills in Developmental Language Disorder and Typical Language Development

Children with developmental language disorder (DLD) show relative weaknesses on rhythm tasks beyond their characteristic linguistic impairments. The current study compares preferred tempo and the width of an entrainment region for 5- to 7-year-old typically developing (TD) children and children with DLD and considers the associations with rhythm aptitude and expressive grammar skills in the two populations. Preferred tempo was measured with a spontaneous motor tempo task (tapping tempo at a comfortable speed), and the width (range) of an entrainment region was measured by the difference between the upper (slow) and lower (fast) limits of tapping a rhythm normalized by an individual's spontaneous motor tempo. Data from N = 16 children with DLD and N = 114 TD children showed that whereas entrainment-region width did not differ across the two groups, slowest motor tempo, the determinant of the upper (slow) limit of the entrainment region, was at a faster tempo in children with DLD vs. TD. In other words, the DLD group could not pace their slow tapping as slowly as the TD group. Entrainment-region width was positively associated with rhythm aptitude and receptive grammar even after taking into account potential confounding factors, whereas expressive grammar did not show an association with any of the tapping measures. Preferred tempo was not associated with any study variables after including covariates in the analyses. These results motivate future neuroscientific studies of low-frequency neural oscillatory mechanisms as the potential neural correlates of entrainment-region width and their associations with musical rhythm and spoken language processing in children with typical and atypical language development.

Sex differences in neural processing of speech in neonates

The large majority of studies shows that girls develop their language skills faster than boys in the first few years of life. Are girls born with this advantage in language development? The present study used fNIRS in neonates to investigate sex differences in neural processing of speech within the first days of life. We found that speech stimuli elicited significantly more brain activity than non-speech stimuli in both groups of male and female neonates. However, whereas girls showed significant HbO changes to speech stimuli only within the left hemisphere, boys exhibited simultaneous neural activations in both hemispheres, with a larger and more significant fronto-temporal cluster in the right hemisphere. Furthermore, in boys, the variation in time-to-peak latencies was considerably greater than in girls. These findings suggest an earlier maturation of language-related brain areas in girls and highlight the importance of sex-specific investigations of neural language networks in infants.

Electroen cephalography correlates of word and non-word listening in children with specific language impairment: An observational study20F0

Auditory processing in children diagnosed with speech and language impairment (SLI) is atypical and characterized by reduced brain activation compared to typically developing (TD) children. In typical speech and language development processes, frontal, temporal, and posterior regions are engaged during single-word listening, while for non-word listening, it is highly unlikely that perceiving or speaking them is not followed by frequent neurones' activation enough to form stable network connections. This study aimed to investigate the electrophysiological cortical activity of alpha rhythm while listening words and non-words in children with SLI compared to TD children. The participants were 50 children with SLI, aged 4 to 6, and 50 age-related TD children. Groups were divided into 2 subgroups: first subgroup - children aged 4.0 to 5.0 years old (E = 25, C = 25) and second subgroup - children aged 5.0 to 6.0 years old (E = 25, C = 25). The younger children's group did not show statistically significant differences in alpha spectral power in word or non-word listening. In contrast, in the older age group for word and non-word listening, differences were present in the prefrontal, temporal, and parieto-occipital regions bilaterally. Children with SLI showed a certain lack of alpha desynchronization in word and non-word listening compared with TD children. Non-word perception arouses more brain regions because of the unknown presence of the word stimuli. The lack of adequate alpha desynchronization is consistent with established difficulties in lexical and phonological processing at the behavioral level in children with SLI.

Attentional modulation of interhemispheric (a)symmetry in children with developmental language disorder

The nature of auditory processing problems in children with developmental language disorder (DLD) is still poorly understood. Much research has been devoted to determining the extent to which DLD is associated with general auditory versus language-specific dysfunction. However, less emphasis has been given to the role of different task conditions in these dysfunctions. We explored whether children with DLD demonstrate atypical interhemispheric asymmetry during the auditory processing of speech and non-speech sounds and whether this interhemispheric balance is modulated by attention. Magnetoencephalography was used to record auditory evoked fields in 18 children (9 to 10 years old), 9 with DLD and 9 with language typical development, during active or passive listening to speech and non-speech sounds. A linear mixed model analysis revealed a bilateral effect of attention in both groups. Participants with DLD demonstrated atypical interhemispheric asymmetry, specifically in the later (185-600 ms) time window but only during the passive listening condition. During the active task, the DLD group did not differ from the typically developed children in terms of hemispheric balance of activation. Our results support the idea of an altered interhemispheric balance in passive auditory response properties in DLD. We further suggest that an active task condition, or top-down attention, can help to regain leftward lateralization, particularly in a later stage of activation. Our study highlights the highly dynamic and interhemispheric nature of auditory processing, which may contribute to the variability in reports of auditory language processing deficits in DLD.

Quantitative MRI reveals differences in striatal myelin in children with DLD

Developmental language disorder (DLD) is a common neurodevelopmental disorder characterised by receptive or expressive language difficulties or both. While theoretical frameworks and empirical studies support the idea that there may be neural correlates of DLD in frontostriatal loops, findings are inconsistent across studies. Here, we use a novel semiquantitative imaging protocol - multi-parameter mapping (MPM) - to investigate microstructural neural differences in children with DLD. The MPM protocol allows us to reproducibly map specific indices of tissue microstructure. In 56 typically developing children and 33 children with DLD, we derived maps of (1) longitudinal relaxation rate R1 (1/T1), (2) transverse relaxation rate R2* (1/T2*), and (3) Magnetization Transfer saturation (MTsat). R1 and MTsat predominantly index myelin, while R2* is sensitive to iron content. Children with DLD showed reductions in MTsat values in the caudate nucleus bilaterally, as well as in the left ventral sensorimotor cortex and Heschl's gyrus. They also had globally lower R1 values. No group differences were noted in R2* maps. Differences in MTsat and R1 were coincident in the caudate nucleus bilaterally. These findings support our hypothesis of corticostriatal abnormalities in DLD and indicate abnormal levels of myelin in the dorsal striatum in children with DLD.

Feedback Processing During Probabilistic Learning in Children With Developmental Language Disorder: An Event-Related Potential Study

PURPOSE

The purpose of this study was to examine feedback processing within the context of probabilistic learning in children with and without developmental language disorder (DLD).

METHOD

The probabilistic category learning task required 28 children ages 8-13 years old to classify novel cartoon animals that differed in five binary features into one of two categories. Performance feedback guided incremental learning of the stimuli classifications. Feedback processing was compared between children with DLD and age-matched children with typical development (TD) by measuring the magnitude of feedback-related event-related potentials. Additionally, the likelihood of each group to repeat a classification of a stimulus following positive feedback ("stay" behavior) and change a classification following negative feedback ("switch" behavior) served as a measure of the consequence of feedback processing.

RESULTS

Children with DLD achieved lower classification accuracy on all learning outcomes compared to their peers with TD. Children with DLD were less likely than those with TD to demonstrate "stay" behavior or to repeat a correct response following positive feedback. "Switch" behavior or changing an incorrect response following negative feedback was found to be at chance level in both groups. Electrophysiological data indicated that children with DLD had a smaller feedback-related negativity effect (i.e., smaller differential processing of positive and negative feedback) when compared to children with TD. Although no differences were found between the two groups in the amplitude of the P3a, strong positive correlations were found between "stay/switch" behavior and the P3a for children in the TD group only.

CONCLUSIONS

Children with DLD do not appear to benefit from incremental corrective feedback to the same extent as their peers with TD. Processing differences are captured in the initial stages of feedback evaluation and in translating information carried by the feedback to inform future actions.

Structural language impairment in Autism Spectrum Disorder versus Loss of Autism Diagnosis: Behavioral and neural characteristics

This study probed for structural language impairment using behavioral and functional neuroimaging methods in individuals with Autism Spectrum Disorder (ASD) and those diagnosed with ASD in childhood who no longer meet criteria for ASD, referred to as Loss of Autism Diagnosis (LAD¹). Participants were drawn from Fein et al. (2013): ASD (n = 35), LAD (n = 31), and Neurotypical (NT; n = 34). Criteria for structural language impairment were: Scores ≤ 82 on Clinical Evaluation of Language Fundamentals-4 (CELF) Core Language, an omnibus measure of language; and scores ≤ 7 on CELF Recalling Sentences, a clinical marker of structural language impairment. Task-based fMRI examined lateralization of significantly activated language-related brain regions in groups with structural language impairment (LI²) versus normal-range language (LN³), collapsed across ASD, LAD¹, and NT status. Results showed no ASD versus LAD group differences in the proportion of participants with structural language impairment according to either metric (Recalling Sentences or Core Language). Functional MRI results indicated greater left hemisphere lateralization within significantly activated regions in the LI² group. Structural language abilities were not meaningfully associated with either social abilities or lifetime ADHD symptoms in LI² subgroups, further suggesting the presence of structural language impairment. Findings indicate the presence of persistent structural language difficulty even in the absence of ASD symptoms in some individuals within the LAD¹ group and unique patterns of language-related neural specialization for language function in LI² relative to LN³.

Plasticity of the language system in children and adults

The language system is perhaps the most unique feature of the human brain's cognitive architecture. It has long been a quest of cognitive neuroscience to understand the neural components that contribute to the hierarchical pattern processing and advanced rule learning required for language. The most important goal of this research is to understand how language becomes impaired when these neural components malfunction or are lost to stroke, and ultimately how we might recover language abilities under these circumstances. Additionally, understanding how the language system develops and how it can reorganize in the face of brain injury or dysfunction could help us to understand brain plasticity in cognitive networks more broadly. In this chapter we will discuss the earliest features of language organization in infants, and how deviations in typical development can-but in some cases, do not-lead to disordered language. We will then survey findings from adult stroke and aphasia research on the potential for recovering language processing in both the remaining left hemisphere tissue and in the non-dominant right hemisphere. Altogether, we hope to present a clear picture of what is known about the capacity for plastic change in the neurobiology of the human language system.

Parent Language Input Prior to School Forecasts Change in Children's Language-Related Cortical Structures During Mid-Adolescence

Children differ widely in their early language development, and this variability has important implications for later life outcomes. Parent language input is a strong experiential factor predicting the variability in children's early language skills. However, little is known about the brain or cognitive mechanisms that underlie the relationship. In addressing this gap, we used longitudinal data spanning 15 years to examine the role of early parental language input that children receive during preschool years in the development of brain structures that support language processing during school years. Using naturalistic parent-child interactions, we measured parental language input (amount and complexity) to children between the ages of 18 and 42 months (n = 23). We then assessed longitudinal changes in children's cortical thickness measured at five time points between 9 and 16 years of age. We focused on specific regions of interest (ROIs) that have been shown to play a role in language processing. Our results support the view that, even after accounting for important covariates such as parental intelligence quotient (IQ) and education, the amount and complexity of language input to a young child prior to school forecasts the rate of change in cortical thickness during the 7-year period from 5½ to 12½ years later. Examining the proximal correlates of change in brain and cognitive differences has the potential to inform targets for effective prevention and intervention strategies.

Implicit manual and oculomotor sequence learning in developmental language disorder

Procedural memory functioning in developmental language disorder (DLD) has largely been investigated by examining implicit sequence learning by the manual motor system. This study examined whether poor sequence learning in DLD is present in the oculomotor domain. Twenty children with DLD and 20 age-matched typically developing (TD) children were presented with a serial reaction time (SRT) task. On the task, a visual stimulus repeatedly appears in different positions on a computer display which prompts a manual response. The children were unaware that on the first three blocks and final block of trials, the visual stimulus followed a sequence. On the fourth block, the stimulus appeared in random positions. Manual reaction times (RT) and saccadic amplitudes were recorded, which assessed sequence learning in the manual and oculomotor domains, respectively. Manual RT were sensitive to sequence learning for the TD group, but not the DLD group. For the TD group, manual RT increased when the random block was presented. This was not the case for the DLD group. In the oculomotor domain, sequence learning was present in both groups. Specifically, sequence learning was found to modulate saccadic amplitudes resulting in both DLD and TD children being able to anticipate the location of the visual stimulus. Overall, the study indicates that not all aspects of the procedural memory system are equally impaired in DLD.

Deep reasoning neural network analysis to predict language deficits from psychometry-driven DWI connectome of young children with persistent language concerns

This study investigated whether current state-of-the-art deep reasoning network analysis on psychometry-driven diffusion tractography connectome can accurately predict expressive and receptive language scores in a cohort of young children with persistent language concerns (n = 31, age: 4.25 ± 2.38 years). A dilated convolutional neural network combined with a relational network (dilated CNN + RN) was trained to reason the nonlinear relationship between "dilated CNN features of language network" and "clinically acquired language score". Three-fold cross-validation was then used to compare the Pearson correlation and mean absolute error (MAE) between dilated CNN + RN-predicted and actual language scores. The dilated CNN + RN outperformed other methods providing the most significant correlation between predicted and actual scores (i.e., Pearson's R/p-value: 1.00/<.001 and .99/<.001 for expressive and receptive language scores, respectively) and yielding MAE: 0.28 and 0.28 for the same scores. The strength of the relationship suggests elevated probability in the prediction of both expressive and receptive language scores (i.e., 1.00 and 1.00, respectively). Specifically, sparse connectivity not only within the right precentral gyrus but also involving the right caudate had the strongest relationship between deficit in both the expressive and receptive language domains. Subsequent subgroup analyses inferred that the effectiveness of the dilated CNN + RN-based prediction of language score(s) was independent of time interval (between MRI and language assessment) and age of MRI, suggesting that the dilated CNN + RN using psychometry-driven diffusion tractography connectome may be useful for prediction of the presence of language disorder, and possibly provide a better understanding of the neurological mechanisms of language deficits in young children.

Left lateralization of neonatal caudate microstructure affects emerging language development at 24 months

The complex interaction between brain and behaviour in language disorder is well established. Yet to date, the imaging literature in the language disorder field has continued to pursue heterogeneous and relatively small clinical cross‐sectional samples, with emphasis on cortical structures and volumetric analyses of subcortical brain structures. In our current work, we aimed to go beyond this state of knowledge to focus on the microstructural features of subcortical brain structures (specifically the caudate nucleus) in a large cohort of neonates and study its association with emerging language skills at 24 months. Variations in neonatal brain microstructure could be interpreted as a proxy for in utero brain development. As language development is highly dependent on cognitive function and home literacy environment, we also examined their effect on the caudate–language function relationship utilizing a conditional process model. Our findings suggest that emerging language development at 24 months is influenced by the degree of left lateralization of neonatal caudate microstructure, indexed by diffusion tensor imaging (DTI)‐derived fractional anisotropy (FA). FA is an indirect measure of neuronal and dendritic density within grey matter structures. We also found that the caudate–language function relationship is partially mediated by cognitive function. The conditional indirect effect of left caudate FA on language composite score through cognitive function was only statistically significant at low levels of home literacy score (−1 standard deviation [SD]). The authors proposed that this may be related to ‘compensatory’ development of cognitive skills in less favourable home literacy environments.

Rapid microstructural plasticity in the cortical semantic network following a short language learning session

Despite the clear importance of language in our life, our vital ability to quickly and effectively learn new words and meanings is neurobiologically poorly understood. Conventional knowledge maintains that language learning—especially in adulthood—is slow and laborious. Furthermore, its structural basis remains unclear. Even though behavioural manifestations of learning are evident near instantly, previous neuroimaging work across a range of semantic categories has largely studied neural changes associated with months or years of practice. Here, we address rapid neuroanatomical plasticity accompanying new lexicon acquisition, specifically focussing on the learning of action-related language, which has been linked to the brain’s motor systems. Our results show that it is possible to measure and to externally modulate (using transcranial magnetic stimulation (TMS) of motor cortex) cortical microanatomic reorganisation after mere minutes of new word learning. Learning-induced microstructural changes, as measured by diffusion kurtosis imaging (DKI) and machine learning-based analysis, were evident in prefrontal, temporal, and parietal neocortical sites, likely reflecting integrative lexico-semantic processing and formation of new memory circuits immediately during the learning tasks. These results suggest a structural basis for the rapid neocortical word encoding mechanism and reveal the causally interactive relationship of modal and associative brain regions in supporting learning and word acquisition.

This combined neuroimaging and brain stimulation study reveals rapid and distributed microstructural plasticity after a single immersive language learning session, demonstrating the causal relevance of the motor cortex in encoding the meaning of novel action words.

Reduced brain activation during spoken language processing in children with developmental language disorder and children with 22q11.2 deletion syndrome

Language difficulties of children with Developmental Language Disorder (DLD) have been associated with multiple underlying factors and are still poorly understood. One way of investigating the mechanisms of DLD language problems is to compare language-related brain activation patterns of children with DLD to those of a population with similar language difficulties and a uniform etiology. Children with 22q11.2 deletion syndrome (22q11DS) constitute such a population. Here, we conducted an fMRI study, in which children (6-10yo) with DLD and 22q11DS listened to speech alternated with reversed speech. We compared language laterality and language-related brain activation levels with those of typically developing (TD) children who performed the same task. The data revealed no significant differences between groups in language lateralization, but task-related activation levels were lower in children with language impairment than in TD children in several nodes of the language network. We conclude that language impairment in children with DLD and in children with 22q11DS may involve (partially) overlapping cortical areas.

The Neurological Basis of Developmental Dyslexia and Related Disorders: A Reappraisal of the Temporal Hypothesis, Twenty Years on

In a now-classic article published a couple of decades ago (Brain, 2000; 123: 2373-2399), I proposed an "extended temporal processing deficit hypothesis of dyslexia", suggesting that a deficit in temporal processing could explain not only language-related peculiarities usually noticed in dyslexic children, but also a wider range of symptoms related to impaired processing of time in general. In the present review paper, I will revisit this "historical" hypothesis both in the light of a new clinical perspective, including the central yet poorly explained notion of comorbidity, and also taking a new look at the most recent experimental work, mainly focusing on brain imaging data. First, consistent with daily clinical practice, I propose to distinguish three groups of children who fail to learn to read, of fairly equal occurrence, who share the same initial presentation (difficulty in mastering the rules of grapheme-phoneme correspondence) but with differing associated signs and/or comorbid conditions (language disorders in the first group, attentional deficits in the second one, and motor coordination problems in the last one), thus suggesting, at least in part, potentially different triggering mechanisms. It is then suggested, in the light of brain imaging information available to date, that the three main clinical presentations/associations of cognitive impairments that compromise reading skills acquisition correspond to three distinct patterns of miswiring or "disconnectivity" in specific brain networks which have in common their involvement in the process of learning and their heavy reliance on temporal features of information processing. With reference to the classic temporal processing deficit of dyslexia and to recent evidence of an inability of the dyslexic brain to achieve adequate coupling of oscillatory brain activity to the temporal features of external events, a general model is proposed according to which a common mechanism of temporal uncoupling between various disconnected-and/or mis-wired-processors may account for distinct forms of specific learning disorders, with reading impairment being a more or less constant feature. Finally, the potential therapeutic implications of such a view are considered, with special emphasis on methods seeking to enhance cross-modal connectivity between separate brain systems, including those using rhythmic and musical training in dyslexic patients.

Learning With and Without Feedback in Children With Developmental Language Disorder

Purpose Intervention provided to school-age children with developmental language disorder often relies on the provision of performance feedback, yet it is unclear whether children with this disorder benefit from feedback-based learning. The study evaluates the effect of performance feedback on learning in children with developmental language disorder. Method Thirteen 8- to 12-year-old children with developmental language disorder and 14 age- and gender-matched children with typical language development completed two learning tasks whose objective was to pair nonword novel names with novel objects. The two tasks differed in the presence of performance feedback to guide learning. Learning outcomes on immediate and follow-up tests were compared between the feedback-based and feedback-free tasks. Additionally, an electrophysiological marker of feedback processing was compared between children with and without developmental language disorder. Results Children with developmental language disorder demonstrated poorer learning outcomes on both tasks when compared with their peers, but both groups achieved better accuracy on the feedback-free task when compared with the feedback-based task. Within the feedback-based task, children were more likely to repeat a correct response than to change it after positive feedback but were as likely to repeat an error as they were to correct it after receiving negative feedback. While children with typical language elicited a feedback-related negativity with greater amplitude to negative feedback, this event-related potential had no amplitude differences between positive and negative feedback in children with developmental language disorder. Conclusions Findings indicate that 8- to 12-year-old children benefit more from a feedback-free learning environment and that negative feedback is not as effective as positive feedback in facilitating learning in children. The behavioral and electrophysiological data provide evidence that feedback processing is impaired in children with developmental language disorders. Future research should evaluate feedback-based learning in children with this disorder using other learning paradigms.

Neurodevelopmental origins of self-limiting rolandic epilepsy: Systematic review of MR imaging studies

Objective

Recent neuroimaging studies have revealed differences in cortical and white matter brain structure in children with self‐limiting rolandic epilepsy (RE). Despite this, reproducibility of the findings has been difficult, and there is no consensus about where and when structural differences are most apparent. We performed a systematic review of quantitative neuroimaging studies in children with RE to explore these questions.

Methods

Using PRISMA guidelines, we used a multilayered search strategy to identify neuroimaging studies in RE. Publications were included if they were quantitative and derived from controlled group studies and passed a quality assessment. Findings of the studies were presented and stratified by duration of epilepsy and age of participants.

Results

We identified six gray matter studies and five white matter studies. Consistent findings were found inside and outside the central sulcus, predominantly within the bilateral frontal and parietal lobes, striatal structures, such as the putamen and white matter, mainly involving the left superior longitudinal fasciculus and connections between the left pre‐ and postcentral gyrus. Stratification of the T1 studies by age found that cortical thickness differences varied between the under and over 10 year olds. Furthermore, the longer the duration of epilepsy, the less likely differences were detected. In white matter studies, there was a reduction in differences with increased age and duration of epilepsy.

Significance

These findings would suggest that the development of regions of the cortex in children with RE is abnormal. These regions are more widespread than the suspected seizure onset zone. Moreover, the findings would suggest that these differences are evidence of neurodevelopmental delay rather than apparent “damage” from the epilepsy.

The relationship between developmental language disorder and dyslexia in European Portuguese school-aged children

Developmental Language Disorder (DLD) [Also referred to as Specific Language Impairment (SLI)] and dyslexia are neurodevelopmental disorders which show similar behavioral manifestations. In this study, between-group comparisons and frequency analysis were combined to investigate the relationship between DLD and dyslexia. European Portuguese children aged 7-10 years, with DLD (N = 7) or dyslexia (N = 11) were recruited and compared to age-matched typically developing (TD) children (N = 21) on phonological processing, language andf literacy measures. The between-group comparison revealed that for phonological processing, the clinical groups scored significantly below TD children on most tasks, yet the DLD group performed similarly to TD children for RAN speed and digit span. The clinical groups did not statistically differ in their phonological processing abilities. For language abilities, children with dyslexia did not differ from TD children, whilst children with DLD performed significantly below TD children on all measures and significantly below children with dyslexia for vocabulary. Finally, for literacy measures, there were no statistical differences between clinical groups which underperformed on all measures when compared to TD children. The frequency analysis showed that children with DLD exhibited a lower prevalence of RAN difficulties when compared to children with dyslexia, whilst children with DLD tended to show more frequent nonword repetition and phoneme deletion deficits. Additionally, whilst children with DLD consistently showed more prevalent language impairments, both clinical groups demonstrated similar prevalence rates of literacy deficits compared to TD children.These findings lend support to the additional deficit model as children with DLD show more severe and prevalent language impairments than those with dyslexia, despite similar phonological and literacy difficulties.

Functional organisation for verb generation in children with developmental language disorder

Developmental language disorder (DLD) is characterised by difficulties in learning one's native language for no apparent reason. These language difficulties occur in 7% of children and are known to limit future academic and social achievement. Our understanding of the brain abnormalities associated with DLD is limited. Here, we used a simple four-minute verb generation task (children saw a picture of an object and were instructed to say an action that goes with that object) to test children between the ages of 10-15 years (DLD N = 50, typically developing N = 67). We also tested 26 children with poor language ability who did not meet our criteria for DLD. Contrary to our registered predictions, we found that children with DLD did not have (i) reduced activity in language relevant regions such as the left inferior frontal cortex; (ii) dysfunctional striatal activity during overt production; or (iii) a reduction in left-lateralised activity in frontal cortex. Indeed, performance of this simple language task evoked activity in children with DLD in the same regions and to a similar level as in typically developing children. Consistent with previous reports, we found sub-threshold group differences in the left inferior frontal gyrus and caudate nuclei, but only when analysis was limited to a subsample of the DLD group (N = 14) who had the poorest performance on the task. Additionally, we used a two-factor model to capture variation in all children studied (N = 143) on a range of neuropsychological tests and found that these language and verbal memory factors correlated with activity in different brain regions. Our findings indicate a lack of support for some neurological models of atypical language learning, such as the procedural deficit hypothesis or the atypical lateralization hypothesis, at least when using simple language tasks that children can perform. These results also emphasise the importance of controlling for and monitoring task performance.

Altered brain structures in the dorsal and ventral language pathways in individuals with and without developmental language disorder (DLD)

Developmental Language Disorder (DLD) is a neurodevelopmental disorder characterized by difficulty learning and using language, and this difficulty cannot be attributed to other developmental conditions. The aim of the current study was to examine structural differences in dorsal and ventral language pathways between adolescents and young adults with and without DLD (age range: 14-27 years) using anatomical magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). Results showed age-related structural brain differences in both dorsal and ventral pathways in individuals with DLD. These findings provide evidence for neuroanatomical correlates of persistent language deficits in adolescents/young adults with DLD, and further suggest that this brain-language relationship in DLD is better characterized by taking account the dynamic course of the disorder along development.

Developmental Language Disorder: Wake and Sleep Epileptiform Discharges and Co-morbid Neurodevelopmental Disorders

Developmental language disorder (DLD) is frequently associated with other developmental diseases and may lead to a handicap through adolescence or adulthood. The aim of our retrospective study was to characterize DLD subgroups, their etiological factors and clinical comorbidities, and the role of epileptiform discharges in wake and sleep recordings. Fifty-five children (42 male, mean age 6.2 ± 1.4 years, range 4-9 years) were included in the present study and underwent phoniatric, psychologic, neurologic, as well as wake and nocturnal electroencephalography (EEG) or polysomnography (PSG) examinations. A receptive form of DLD was determined in 34 children (63.0%), and an expressive form was found in 20 children (37.0%). Poor cooperation in one child did not permit exact classification. DLD children with the receptive form had significantly lower mean phonemic hearing (79.1% ± 10.9) in comparison with those with the expressive form (89.7% ± 6.2, p < 0.001). A high amount of perinatal risk factors was found in both groups (50.9%) as well as comorbid developmental diseases. Developmental motor coordination disorder was diagnosed in 33 children (61.1%), and attention deficit or hyperactivity disorder was diagnosed in 39 children (70.9%). Almost one half of DLD children (49.1%) showed abnormalities on the wake EEG; epileptiform discharges were found in 20 children (36.4%). Nocturnal EEG and PSG recordings showed enhanced epileptiform discharges, and they were found in 30 children (55.6%, p = 0.01). The wake EEG showed focal discharges predominantly in the temporal or temporo-parieto-occipital regions bilaterally, while in the sleep recordings, focal activity was shifted to the fronto-temporo-central areas (p < 0.001). Almost all epileptiform discharges appeared in non-rapid eye movement (NREM) sleep. A close connection was found between DLD and perinatal risk factors, as well as neurodevelopmental disorders. Epileptiform discharges showed an enhancement in nocturnal sleep, and the distribution of focal discharges changed.

Procedural and declarative memory brain systems in developmental language disorder (DLD)

The aim of the current study was to examine microstructural differences in white matter relevant to procedural and declarative memory between adolescents/young adults with and without Developmental Language Disorder (DLD) using diffusion tensor imaging (DTI). The findings showed atypical age-related changes in white matter structures in the corticostriatal system, in the corticocerebellar system, and in the medial temporal region in individuals with DLD. Results highlight the importance of considering the age factor in research on DLD. Future studies are needed to examine the developmental relationship between long-term memory and individual differences in language development and learning.

What Are the Peer Interaction Strengths and Difficulties in Children with Developmental Language Disorder? A Systematic Review

The current review gathers together research investigating peer interaction skills in children with Developmental Language Disorder (DLD) to give an overview of the strengths and challenges experienced by these children when interacting with other children. A systematic review was conducted to summarise the literature on peer interaction strengths and difficulties in children with DLD. No restrictions on time-period were made and the selection criteria accounted for many of the diagnostic labels previously used to refer to DLD. Studies included in this review involve English-speaking children of UK primary school age (4-11 years). A systematic search of databases identified 28 papers that met the inclusion criteria. Children with DLD are found to experience many challenges when interacting with peers. Difficulties have been found in studies exploring discourse characteristics such as turn-taking and in behaviours during play, such as access behaviours. Heterogeneity was however notable and peer interaction strengths are found in terms of the children's abilities to make friends, use verbal and non-verbal behaviour to make joint decisions with peers, and abilities to engage with peers in social pretend play. While it is encouraging to find research exploring many different areas of peer interaction competence in children with DLD, the research is highly disparate and there are many research findings awaiting replication. The current evidence base is unable to comprehensively define the characteristics of peer interactions of children with DLD.

Altered efficiency of white matter connections for language function in children with language disorder

To characterize structural white matter substrates associated with language functions in children with language disorders (LD), a psychometry-driven diffusion tractography network was investigated with canonical correlation analysis (CCA), which can reliably predict expressive and receptive language scores from the nodal efficiency (NE) of the obtained network. The CCA found that the NE values of six regions: left inferior-frontal-opercular, left insular, left angular gyrus, left superior-temporal-gyrus, right hippocampus, and right cerebellar-lobule were highly correlated with language scores (ρ_expressive/ρ_receptive = 0.609/0.528), yielding significant differentiation of LD from controls using new imaging predictors u_expressive (F = 15.024, p = .0003) and u_receptive (F = 7.421, p = .009). This study demonstrates the utility of intrinsic language network analyses in distinguishing and potentially subtyping the type and severity of language deficit, especially in very young children (≤3 years) with LD. The use of structural imaging to identify children with persisting language disorder could prove useful in understanding the etiology of language disorder.

The mis-wired language network in children with developmental language disorder: insights from DTI tractography

This study aims to detect the neural substrate underlying the language impairment in children with developmental language disorder (DLD) using diffusion tensor imaging (DTI) tractography. Deterministic DTI tractography was performed in a group of right-handed children with DLD (N = 17; mean age 10;07 ± 2;01 years) and a typically developing control group matched for age, gender and handedness (N = 22; mean age 11;00 ± 1;11 years) to bilaterally identify the superior longitudinal fascicle, arcuate fascicle, anterior lateral segment and posterior lateral segment (also called dorsal language network) and the middle and inferior longitudinal fascicle, extreme capsule fiber system and uncinate fascicle (also called ventral language network). Language skills were assessed using an extensive, standardized test battery. Differences in language performance, white matter organization and structural lateralization of the language network were statistically analyzed. Children with DLD showed a higher overall volume and higher ADC values for the left-hemispheric language related WM tracts. In addition, in children with DLD, the majority (88%; 7/8) of the studied language related WM tracts did not show a significant left or right lateralization pattern. These structural alterations might underlie the language impairment in children with DLD.

Functional magnetic resonance imaging

Among the range of methods available to assess neurodevelopmental disorders, functional MRI (fMRI) has been a preferred tool of choice. Indeed, fMRI can reveal functional alterations in brain networks, irrespective of their structural integrity. Yet, whether fMRI studies have provided unique added value and influenced the clinical care and assessments in children with these conditions remains controversial. This chapter aims to give an overview of the clinical use of task-based as well as resting-state fMRI in children with neurodevelopmental disorders, such as dyslexia, DLD, and epilepsy. We introduce analysis methods that appear promising (namely PPI and machine learning) and describe strengths and limitations of fMRI in the field of pediatrics. Altogether, we suggest that fMRI has provided us with a unique understanding of some developmental conditions. Indeed, findings from group studies have both informed neuroanatomical models and revealed compensation mechanisms. In addition, improvements have made fMRI an increasingly child-friendly method. Nevertheless, clinicians should be aware of limitations, including (1) lack of replication of results, (2) the limited specificity as a diagnostic tool, and (3) difficulties with interpretation of findings. The use of fMRI in the clinic currently remains restricted, with the exception of epilepsy surgery planning, where it is used routinely.

Investigation into inconsistent lateralisation of language functions as a potential risk factor for language impairment

Disruption to language lateralisation has been proposed as a cause of developmental language impairments. In this study, we tested the idea that consistency of lateralisation across different language functions is associated with language ability. A large sample of adults with variable language abilities (N = 67 with a developmental disorder affecting language and N = 37 controls) were recruited. Lateralisation was measured using functional transcranial Doppler sonography (fTCD) for three language tasks that engage different language subprocesses (phonological decision, semantic decision and sentence generation). The whole sample was divided into those with consistent versus inconsistent lateralisation across the three tasks. Language ability (using a battery of standardised tests) was compared between the consistent and inconsistent groups. The results did not show a significant effect of lateralisation consistency on language skills. However, of the 31 individuals showing inconsistent lateralisation, the vast majority (84%) were in the disorder group with only five controls showing such a pattern, a difference that was higher than would be expected by chance. The developmental disorder group also demonstrated weaker correlations between laterality indices across pairs of tasks. In summary, although the data did not support the hypothesis that inconsistent language lateralisation is a major cause of poor language skills, the results suggested that some subtypes of language disorder are associated with inefficient distribution of language functions between hemispheres. Inconsistent lateralisation could be a causal factor in the aetiology of language disorder or may arise in some cases as the consequence of developmental disorder, possibly reflective of compensatory reorganisation.

Grey matter volume in developmental speech and language disorder

Developmental language disorder (DLD) and developmental speech disorder (DSD) are common, yet their etiologies are not well understood. Atypical volume of the inferior and posterior language regions and striatum have been reported in DLD; however, variability in both methodology and study findings limits interpretations. Imaging research within DSD, on the other hand, is scarce. The present study compared grey matter volume in children with DLD, DSD, and typically developing speech and language. Compared to typically developing controls, children with DLD had larger volume in the right cerebellum, possibly associated with the procedural learning deficits that have been proposed in DLD. Children with DSD showed larger volume in the left inferior occipital lobe compared to controls, which may indicate a compensatory role of the visual processing regions due to sub-optimal auditory-perceptual processes. Overall, these findings suggest that different neural systems may be involved in the specific deficits related to DLD and DSD.

Auditory perception is associated with implicit language learning and receptive language ability in autism spectrum disorder

BACKGROUND

Autism spectrum disorder (ASD) is associated with language impairment as well as atypical auditory sensory processing. The current study investigated associations among auditory perception, implicit language learning and receptive language ability in youth with ASD.

METHODS

We measured auditory event related potentials (ERP) during an artificial language statistical learning task in 76 youth with ASD and 27 neurotypical (NT) controls. Participants with ASD had a broad range of cognitive and language abilities.

RESULTS

NT youth showed evidence of implicit learning via attenuated P1 amplitude in the left hemisphere. In contrast, among youth with ASD, implicit learning elicited bilateral attenuation that was increasingly evident with greater receptive language skill.

CONCLUSIONS

Efficient early auditory perception reflects language learning and is a marker of language ability among youth with ASD. Atypical lateralization of word learning is evident in ASD across a broad range of receptive language abilities.

When two are better than one: Bilateral mesial temporal lobe contributions associated with better vocabulary skills in children and adolescents

This study considered the involvement of the mesial temporal lobe (MTL) in language and verbal memory functions in healthy children and adolescents. We investigated 30 healthy, right-handed children and adolescents, aged 7-16, with a fMRI language paradigm and a comprehensive cognitive test battery. We found significant MTL activations during language fMRI in all participants; 63% of them had left lateralized MTL activations, 20% exhibited right MTL lateralization, and 17% showed bilateral MTL involvement during the fMRI language paradigm. Group analyses demonstrated a strong negative correlation between the lateralization of MTL activations and language functions. Specifically, children with less lateralized MTL activation showed significantly better vocabulary skills. These findings suggest that the mesial temporal lobes of both hemispheres play an important role in language functioning, even in right-handers. Our results furthermore show that bilateral mesial temporal lobe involvement is advantageous for vocabulary skills in healthy, right-handed children and adolescents.

Why parametric measures are critical for understanding typical and atypical cognitive development

Children's cognitive abilities improve significantly over childhood and adolescence. We know from behavioral research that core cognitive processes such as working memory and mental attention improve significantly across development. Functional magnetic resonance imaging (fMRI) allows for investigating the typically developing, living brain in action. In the last twenty years we have learned a great deal about brain correlates associated with how adults hold and manipulate information in mind, however, neurocognitive correlates across development remain inconsistent. We present developmental fMRI findings on cognitive processes such as working memory and mental attention and discuss methodological and theoretical issues in the assessment of cognitive limitations in the visual spatial and verbal domains. We also review data from typical and atypical development and emphasize the unique contribution parametric measures can make in understanding neurocognitive correlates of typical and atypical development.