Genetic influences on language impairment and phonological short-term memory

Word Learning in Arabic Diglossia in Children With Typical Language Development and Developmental Language Disorder

PURPOSE

Word learning requires the creation of phonological and semantic representations and links in long-term memory. Phonological distance of a given word from the spoken language affects children's lexical-phonological representations and processing. The study investigates the role of the phonological distance of Modern Standard Arabic (StA) words from the child's Spoken Arabic (SpA) vernacular in word learning in Arabic diglossia. It also examines whether, given their vulnerable phonological skills, children with developmental language disorder (DLD) show a stronger impact of phonological distance on word learning than children with typical language development (TLD).

METHOD

One hundred children with TLD and DLD in kindergarten and in first grade (25 per group) were tested on comprehension and production word-learning probes manipulating phonological distance. Learning monosyllabic and disyllabic nonwords encoding only SpA phonemes was compared with the learning of parallel nonwords encoding one unique StA consonant each.

RESULTS

Repeated-measures analyses of variance showed higher word learning scores in children with TLD on both probes and for both syllable lengths. Moreover, all children fared significantly lower, in both comprehension and production probes, when the target stimulus was phonologically distant from the spoken language. Finally, an interaction effect was observed on the production probes, revealing differences in the developmental dynamics of phonological distance effects between the groups: Phonological distance hindered word learning among children with TLD in kindergarten, but among children with DLD in the first grade.

CONCLUSIONS

The results support the role of phonological distance as a phonological complexity factor in word learning in Arabic diglossia. Furthermore, they show that the effect of phonological distance is complex and it interacts with modality, language aptitude, and grade level. The theoretical and clinical implications are discussed.

Lateralization of Neural Speech Discrimination at Birth Is a Predictor for Later Language Development

Newborns are able to neurally discriminate between speech and nonspeech right after birth. To date it remains unknown whether this early speech discrimination and the underlying neural language network is associated with later language development. Preterm-born children are an interesting cohort to investigate this relationship, as previous studies have shown that preterm-born neonates exhibit alterations of speech processing and have a greater risk of later language deficits. This investigation also holds clinical importance, as differences in neonatal speech discrimination and its functional networks may serve as predictors of later language outcomes. We therefore investigated neural speech discrimination using functional near-infrared spectroscopy in 92 preterm- and term-born neonates and its predictive value for language development in 45 of them. Three to five years later, preterm-born and term-born children did not significantly differ in language comprehension, sentence production, the use of morphological rules, or phonological short-term memory. In addition, the gestational age at birth was not a significant predictor of language development. Neural speech discrimination, in contrast, was strongly correlated with later phonological short-term memory. However, not the extent of speech discrimination, but rather its lateralization, was a predictor of language development. Children with less right hemisphere involvement-and therefore more left-lateralized speech discrimination at birth-showed better development of phonological short-term memory three to five years later. These findings suggest that the ability of fetuses to form memory traces is reflected by neonatal abilities to neurally discriminate speech, which in turn is a predictor for later phonological short-term memory.

Imaging genetics of language network functional connectivity reveals links with language-related abilities, dyslexia and handedness

Language is supported by a distributed network of brain regions with a particular contribution from the left hemisphere. A multi-level understanding of this network requires studying its genetic architecture. We used resting-state imaging data from 29,681 participants (UK Biobank) to measure connectivity between 18 left-hemisphere regions involved in multimodal sentence-level processing, as well as their right-hemisphere homotopes, and interhemispheric connections. Multivariate genome-wide association analysis of this total network, based on genetic variants with population frequencies  >1%, identified 14 genomic loci, of which three were also associated with asymmetry of intrahemispheric connectivity. Polygenic dispositions to lower language-related abilities, dyslexia and left-handedness were associated with generally reduced leftward asymmetry of functional connectivity. Exome-wide association analysis based on rare, protein-altering variants (frequencies <1%) suggested 7 additional genes. These findings shed new light on genetic contributions to language network organization and related behavioural traits.

Predictive validity of a parental questionnaire for identifying children with developmental language disorders

Background

The underdiagnosis of developmental language disorder (DLD) in children is a serious problem in developing countries with limited resources. It has long been noted that the concerns parents have about their children's health and development are richly informative, and if this information can be used for diagnosis, it may provide a means to address the problem of underdiagnosis of DLD. This study aimed to quantify the utility of parental linguistic concern questions (PLCQ) on the identification of language disorders in monolingual Spanish-speaking children in Mexico. It also explored whether a combination of biological and environmental conditions questions (BECQ) might improve the performance of a screening test to identify DLD.

Methods

A total of 680 monolingual Mexican Spanish-speaking children and their parents from urban areas in Mexico participated in the study. The distribution of responses to questions about DLD concerns was compared between 185 children diagnosed with DLD and 495 control subjects, and multiple logistic regression analysis was performed to select questions with high predictivity, based on the Akaike information criterion. The diagnostic utility of the questions was assessed by receiver operating characteristic (ROC) curves, stratum-specific likelihood ratios (SSLRs), and changes in pretest and post-test probabilities of DLD. A similar procedure was used to explore whether adding BECQ would improve the diagnostic utility of questions about DLD concerns using data of 128 children.

Results

Four questions regarding parental linguistic concerns were found to be useful in identifying children with DLD. When all four concerns were present, the SSLR was 8.79, while it was only 0.27 when there were no concerns at all. The estimates of DLD probability increased from 0.12 to 0.55 at pretest and post-test. On the other hand, the BECQ did not perform as well as the PLCQ in identifying DLD, and the improvement in diagnostic performance it provided was limited to one question.

Conclusion

The parental questionnaire can be used as a screening tool to help in identifying children with DLD. The data presented in this study underscore the importance of considering linguistic parental concerns as part of the screening process. This is a realistic option to provide a solution to the current problem of underdiagnosis of DLD in Mexico.

Executive Function and Working Memory Deficits in Females with Fragile X Premutation

The Fragile X premutation is a genetic instability of the FMR1 gene caused by 55–199 recurrences of the CGG sequence, whereas there are only 7–54 repeats of the CGG sequence in the normal condition. While males with the premutation of Fragile X were found to have difficulties in executive functions and working memory, little data have been collected on females. This study is among the first to address executive functions and phonological memory in females with the Fragile X premutation. Twenty-three female carriers aged 20–55 years and twelve non carrier females matched in age and levels of education (in years) participated in this study. Executive functions and phonological memory were assessed using the self-report questionnaire The Behavior Rating Inventory of Executive Function (BRIEF) and behavioral measures (nonword repetitions, forward and backward digit span). Females who were carriers of the premutation of the FMR1 gene reported less efficient executive functions in the BRIEF questionnaire compared to the control group. In addition, a relationship was found between the number of repetitions on the CGG sequence of nucleotides, nonword repetitions, and forward digit span. The findings suggest that the premutation of Fragile X in females affects their performance of executive functions and may have impact on everyday functioning.

Language profile of children from a quilombola community

PURPOSE

to identify linguistic performance (expressive vocabulary, phonology and narrative) and cognitive performance (Verbal Short-Term Memory (VSTM)) of preschoolers living in a quilombola community.

METHODS

Twenty-four quilombola preschoolers aged four (4) and five (5) years with no complaints in language development participated in the study. Most families were in the D-E class and maternal and paternal education was lower than high school. Their guardians answered a questionnaire about their previous development, family practices and socioeconomic aspects, while the assessment included tests of expressive vocabulary, phonology, narrative and verbal short-term memory. The data collected were subjected to descriptive statistical analysis to characterize family practices, socioeconomic aspects and linguistic and cognitive performance, inferential analysis used Fisher's exact test to compare performance between subjects aged 4 and 5 years and also to compare performance according to family practices.

RESULTS

78.3% of preschoolers performed adequately in vocabulary and 79.2% in phonology; and 63.6% had the narrative classified as descriptive. 82.6% had a VSTM task performance below the expected for age.

CONCLUSION

Although the preschoolers in this study had functional communication, their profile of language development and cognitive skills was more vulnerable and may have an impact on their school trajectory.

Pleiotropy between language impairment and broader behavioral disorders-an investigation of both common and rare genetic variants

BACKGROUND

Language plays a major role in human behavior. For this reason, neurodevelopmental and psychiatric disorders in which linguistic ability is impaired could have a big impact on the individual's social interaction and general wellbeing. Such disorders tend to have a strong genetic component, but most past studies examined mostly the linguistic overlaps across these disorders; investigations into their genetic overlaps are limited. The aim of this study was to assess the potential genetic overlap between language impairment and broader behavioral disorders employing methods capturing both common and rare genetic variants.

METHODS

We employ polygenic risk scores (PRS) trained on specific language impairment (SLI) to evaluate genetic overlap across several disorders in a large case-cohort sample comprising ~13,000 autism spectrum disorder (ASD) cases, including cases of childhood autism and Asperger's syndrome, ~15,000 attention deficit/hyperactivity disorder (ADHD) cases, ~3000 schizophrenia cases, and ~21,000 population controls. We also examine rare variants in SLI/language-related genes in a subset of the sample that was exome-sequenced using the SKAT-O method.

RESULTS

We find that there is little evidence for genetic overlap between SLI and ADHD, schizophrenia, and ASD, the latter being in line with results of linguistic analyses in past studies. However, we observe a small, significant genetic overlap between SLI and childhood autism specifically, which we do not observe for SLI and Asperger's syndrome. Moreover, we observe that childhood autism cases have significantly higher SLI-trained PRS compared to Asperger's syndrome cases; these results correspond well to the linguistic profiles of both disorders. Our rare variant analyses provide suggestive evidence of association for specific genes with ASD, childhood autism, and schizophrenia.

CONCLUSIONS

Our study provides, for the first time, to our knowledge, genetic evidence for ASD subtypes based on risk variants for language impairment.

Spike Generators and Cell Signaling in the Human Auditory Nerve: An Ultrastructural, Super-Resolution, and Gene Hybridization Study

Background: The human auditory nerve contains 30,000 nerve fibers (NFs) that relay complex speech information to the brain with spectacular acuity. How speech is coded and influenced by various conditions is not known. It is also uncertain whether human nerve signaling involves exclusive proteins and gene manifestations compared with that of other species. Such information is difficult to determine due to the vulnerable, "esoteric," and encapsulated human ear surrounded by the hardest bone in the body. We collected human inner ear material for nanoscale visualization combining transmission electron microscopy (TEM), super-resolution structured illumination microscopy (SR-SIM), and RNA-scope analysis for the first time. Our aim was to gain information about the molecular instruments in human auditory nerve processing and deviations, and ways to perform electric modeling of prosthetic devices. Material and Methods: Human tissue was collected during trans-cochlear procedures to remove petro-clival meningioma after ethical permission. Cochlear neurons were processed for electron microscopy, confocal microscopy (CM), SR-SIM, and high-sensitive in situ hybridization for labeling single mRNA transcripts to detect ion channel and transporter proteins associated with nerve signal initiation and conductance. Results: Transport proteins and RNA transcripts were localized at the subcellular level. Hemi-nodal proteins were identified beneath the inner hair cells (IHCs). Voltage-gated ion channels (VGICs) were expressed in the spiral ganglion (SG) and axonal initial segments (AISs). Nodes of Ranvier (NR) expressed Nav1.6 proteins, and encoding genes critical for inter-cellular coupling were disclosed. Discussion: Our results suggest that initial spike generators are located beneath the IHCs in humans. The first NRs appear at different places. Additional spike generators and transcellular communication may boost, sharpen, and synchronize afferent signals by cell clusters at different frequency bands. These instruments may be essential for the filtering of complex sounds and may be challenged by various pathological conditions.

A genetic window to auditory-verbal problems in bipolar disorder

Bipolar disorder is a high prevalent psychiatric condition entailing recurrent episodes of elevated mood and depression, but also diverse cognitive problems. One deficit observed in patients concerns to auditory-verbal processing. Being a hereditary condition with a complex genetic architecture, it is not clear which genes contribute to this deficit. We show that candidates for bipolar disorder significantly overlap with candidates for clinical conditions resulting from a deficit in the phonological loop of working memory, particularly, developmental dyslexia and specific language impairment. The overlapping genes are involved in aspects of brain development and function (particularly, brain oscillations) potentially underlying phonological processing and accordingly, emerge as promising candidates for auditory-verbal deficits in bipolar disorder.

Associations and Dissociations among Phonological Processing Skills, Language Skills and Nonverbal Cognition in Individuals with Autism Spectrum Disorder

AIMS

The purpose of this study was to examine the nature of phonological processing in individuals with autism spectrum disorder (ASD) as it pertains to their nonverbal cognitive and linguistic abilities.

METHODS

Twenty-one participants between the ages of 9 and 21 years were administered a nonverbal cognitive assessment (Raven test), a language measure that requires receptive and expressive knowledge of semantics, syntax and morphology, as well as the integration across these language domains (CELF-4), and a measure of phonological processing (CTOPP).

RESULTS

Results show that performance on nonword repetition (NWR) that reflects an aspect of phonological memory was significantly low, whereas performance on phoneme reversal, phoneme elision, blending words and memory for digits was within the normal range. Hierarchical regressions with age, nonverbal intelligence (Raven test) and receptive language (CELF) as predictors showed that for NWR and phoneme elision the receptive part of the CELF was the main significant -predictor, after controlling for age. For phoneme reversal and memory for digits, however, the Raven score was the significant predictor, suggesting that cognitive nonverbal ability is the main factor explaining variability in these tasks.

CONCLUSIONS

A deficit in phonological memory characterizes individuals in the autistic population. This deficit may influence language acquisition in this population consistent with other populations of children with language impairments. Other tasks of phonological awareness, however, might be preserved especially when they do not involve memory for long phonological sequences and when the cognitive abilities are within the norm.

The Association of Dyslexia and Developmental Speech and Language Disorder Candidate Genes with Reading and Language Abilities in Adults

Reading and language abilities are critical for educational achievement and success in adulthood. Variation in these traits is highly heritable, but the underlying genetic architecture is largely undiscovered. Genetic studies of reading and language skills traditionally focus on children with developmental disorders; however, much larger unselected adult samples are available, increasing power to identify associations with specific genetic variants of small effect size. We introduce an Australian adult population cohort (41.7-73.2 years of age, N = 1505) in which we obtained data using validated measures of several aspects of reading and language abilities. We performed genetic association analysis for a reading and spelling composite score, nonword reading (assessing phonological processing: a core component in learning to read), phonetic spelling, self-reported reading impairment and nonword repetition (a marker of language ability). Given the limited power in a sample of this size (~80% power to find a minimum effect size of 0.005), we focused on analyzing candidate genes that have been associated with dyslexia and developmental speech and language disorders in prior studies. In gene-based tests, FOXP2, a gene implicated in speech/language disorders, was associated with nonword repetition (p < .001), phonetic spelling (p = .002) and the reading and spelling composite score (p < .001). Gene-set analyses of candidate dyslexia and speech/language disorder genes were not significant. These findings contribute to the assessment of genetic associations in reading and language disorders, crucial for understanding their etiology and informing intervention strategies, and validate the approach of using unselected adult samples for gene discovery in language and reading.

Gene Expression Correlates of the Cortical Network Underlying Sentence Processing

A pivotal question in modern neuroscience is which genes regulate brain circuits that underlie cognitive functions. However, the field is still in its infancy. Here we report an integrated investigation of the high-level language network (i.e., sentence-processing network) in the human cerebral cortex, combining regional gene expression profiles, task fMRI, large-scale neuroimaging meta-analysis, and resting-state functional network approaches. We revealed reliable gene expression-functional network correlations using three different network definition strategies, and identified a consensus set of genes related to connectivity within the sentence-processing network. The genes involved showed enrichment for neural development and actin-related functions, as well as association signals with autism, which can involve disrupted language functioning. Our findings help elucidate the molecular basis of the brain's infrastructure for language. The integrative approach described here will be useful for studying other complex cognitive traits.

The Role of Phonological Working Memory and Environmental Factors in Lexical Development in Italian-Speaking Late Talkers: A One-Year Follow-Up Study

PURPOSE

This follow-up study assessed (a) the influence of phonological working memory (pWM), home literacy environment, and a family history of linguistic impairments in late talkers (LTs); (b) the diagnostic accuracy of a task of nonword repetition (NWR) in identifying LTs; and (c) the persistence of lexical weaknesses after 10 months.

METHOD

Two hundred ninety-three children were assessed at approximately 32 (t1) and 41 (t2) months. At t1, they were administered the Italian adaptation of the Language Development Survey, an NWR task (used to assess pWM), and questionnaires assessing home literacy environment and family history of language impairments. Thirty-three LTs were identified. The linguistic skills of the participants were evaluated at t2 by administering tasks assessing Articulation, Naming, Semantic Fluency, and Lexical Comprehension.

RESULTS

At t2, LTs performed more poorly as compared with age-matched typically developing peers in articulatory and naming skills, had reduced lexical comprehension abilities, and had limited lexical knowledge. Their performance on the NWR task at t1 correlated with the extension of their vocabularies at t2 (as estimated with a Semantic Fluency task).

CONCLUSIONS

The Language Development Survey recently adapted to Italian is sensitive to LTs. Former LTs still have a mild lexical delay at approximately 40 months. As an indirect measure of pWM, the task of NWR is an early indicator of future lexical deficits.

Impact of Diglossia on Word and Non-word Repetition among Language Impaired and Typically Developing Arabic Native Speaking Children

The study tested the impact of the phonological and lexical distance between a dialect of Palestinian Arabic spoken in the north of Israel (SpA) and Modern Standard Arabic (StA or MSA) on word and non-word repetition in children with specific language impairment (SLI) and in typically developing (TD) age-matched controls. Fifty kindergarten children (25 SLI, 25 TD; mean age 5;5) and fifty first grade children (25 SLI, 25 TD; mean age 6:11) were tested with a repetition task for 1-4 syllable long real words and pseudo words; Items varied systematically in whether each encoded a novel StA phoneme or not, namely a phoneme that is only used in StA but not in the spoken dialect targeted. Real words also varied in whether they were lexically novel, meaning whether the word is used only in StA, but not in SpA. SLI children were found to significantly underperform TD children on all repetition tasks indicating a general phonological memory deficit. More interesting for the current investigation is the observed strong and consistent effect of phonological novelty on word and non-word repetition in SLI and TD children, with a stronger effect observed in SLI. In contrast with phonological novelty, the effect of lexical novelty on word repetition was limited and it did not interact with group. The results are argued to reflect the role of linguistic distance in phonological memory for novel linguistic units in Arabic SLI and, hence, to support a specific Linguistic Distance Hypothesis of SLI in a diglossic setting. The implications of the findings for assessment, diagnosis and intervention with Arabic speaking children with SLI are discussed.

Common variation in the autism risk gene CNTNAP2, brain structural connectivity and multisensory speech integration

Three lines of evidence motivated this study. 1) CNTNAP2 variation is associated with autism risk and speech-language development. 2) CNTNAP2 variations are associated with differences in white matter (WM) tracts comprising the speech-language circuitry. 3) Children with autism show impairment in multisensory speech perception. Here, we asked whether an autism risk-associated CNTNAP2 single nucleotide polymorphism in neurotypical adults was associated with multisensory speech perception performance, and whether such a genotype-phenotype association was mediated through white matter tract integrity in speech-language circuitry. Risk genotype at rs7794745 was associated with decreased benefit from visual speech and lower fractional anisotropy (FA) in several WM tracts (right precentral gyrus, left anterior corona radiata, right retrolenticular internal capsule). These structural connectivity differences were found to mediate the effect of genotype on audiovisual speech perception, shedding light on possible pathogenic pathways in autism and biological sources of inter-individual variation in audiovisual speech processing in neurotypicals.

A Sentence Repetition Task for Catalan-Speaking Typically-Developing Children and Children with Specific Language Impairment

It is common to find that so-called minority languages enjoy fewer (if any) diagnostic tools than the so-called majority languages. This has repercussions for the detection and proper assessment of children with Specific Language Impairment (SLI) brought up in these languages. With a view to remedy this situation for Catalan, I developed a sentence repetition task to assess grammatical maturity in school-age children; in current practice, Catalan-speaking children are assessed with tests translated from Spanish, with disregard of the fact that the markers of SLI may differ substantially from one language to another, even between closely related languages. The test proposed here is inspired by SASIT [School-Age Sentence Imitation Test - English], designed for English by Marinis et al. (2011); some of the constructions targeted are challenging in a subset of languages, but not others, and are included because they are indeed affected in Catalan SLI; other constructions appear to be disrupted universally. The test involves canonical SVO sentences, sentences with third person accusative clitics (known to be problematic in Catalan SLI, but not in Spanish), passives, wh- interrogatives, subordinate clauses, subject and object relatives and conditionals. The test was administered to thirty typically developing 6- and 7-year-olds (as reported in Gavarró et al., 2012b), and five children diagnosed with SLI (mean age 10;7). The results of the task were scored under two systems: (i) identical vs. non-identical repetition and (ii) identical, grammatical and ungrammatical repetition, with detail regarding the error type. The results for typically developing and SLI children showed differences between the groups: identical repetition was found in 88.9% of cases for typically developing children but only 48% for SLI children. Ungrammatical productions were higher for the SLI group, and so were grammatical but different repetitions, a trend which was found in every child individually. The results are compared to those available in the literature for similar languages and I discuss the impact of grammatical variation in language performance, in both typical and impaired development.

How Common are WM Deficits in Children with Difficulties in Reading and Mathematics?

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Children's learning abilities were associated with WM.

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The link with verbal WM was stronger for reading than mathematics.

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The majority of children with learning difficulties had WM deficits.

The extent to which deficits in working memory (WM) are characteristic of children with reading and mathematics difficulties was investigated in a large sample aged 5–15 years reported to have problems in attention, learning and memory. WM performance was highly correlated with reading and mathematics scores. Although deficits in individual tests of short-term memory (STM) and WM occurred in less than half of the children with detected learning difficulties, three-quarters of the children with low reading and mathematics scores obtained one or more WM scores in the deficit range. These findings are consistent with proposals that WM or the broader cognitive dimensions it taps impede school-based learning, and point to the importance of managing WM loads in the classroom.

Impact of specific language impairment and type of school on different language subsystems

PURPOSE

This study aimed to explore quantitative and qualitative effects of type of school and specific language impairment (SLI) on different language abilities.

METHODS

204 Brazilian children aged from 4 to 6 years old participated in the study. Children were selected to form three groups: 1) 63 typically developing children studying in private schools (TDPri); 2) 102 typically developing children studying in state schools (TDSta); and 39 children with SLI studying in state schools (SLISta). All individuals were assessed regarding expressive vocabulary, number morphology and morphosyntactic comprehension.

RESULTS

All language subsystems were vulnerable to both environmental (type of school) and biological (SLI) effects. The relationship between the three language measures was exactly the same to all groups: vocabulary growth correlated with age and with the development of morphological abilities and morphosyntactic comprehension. Children with SLI showed atypical errors in the comprehension test at the age of 4, but presented a pattern of errors that gradually resembled typical development.

CONCLUSION

The effect of type of school was marked by quantitative differences, while the effect of SLI was characterised by both quantitative and qualitative differences.

Working memory training involves learning new skills

We present a new framework characterizing training-induced changes in WM as the acquisition of novel cognitive routines akin to learning a new skill. Predictions were tested in three studies analyzing the transfer between WM tasks following WM training. Study 1 reports a meta-analysis establishing substantial transfer when trained and untrained tasks shared either a serial recall, complex span or backward span paradigm. Transfer was weaker for serial recall of verbal than visuo-spatial material, suggesting that this paradigm is served by an existing verbal STM system and does not require a new routine. Re-analysis of published WM training data in Study 2 showed that transfer was restricted to tasks sharing properties proposed to require new routines. In a re-analysis of data from four studies, Study 3 demonstrated that transfer was greatest for children with higher fluid cognitive abilities. These findings suggest that development of new routines depends on general cognitive resources and that they can only be applied to other similarly-structured tasks.

An examination of the language construct in NIMH's research domain criteria: Time for reconceptualization!

The National Institute of Mental Health's Research Domain Criteria (RDoC) Initiative "calls for the development of new ways of classifying psychopathology based on dimensions of observable behavior." As a result of this ambitious initiative, language has been identified as an independent construct in the RDoC matrix. In this article, we frame language within an evolutionary and neuropsychological context and discuss some of the limitations to the current measurements of language. Findings from genomics and the neuroimaging of performance during language tasks are discussed in relation to serious mental illness and within the context of caveats regarding measuring language. Indeed, the data collection and analysis methods employed to assay language have been both aided and constrained by the available technologies, methodologies, and conceptual definitions. Consequently, different fields of language research show inconsistent definitions of language that have become increasingly broad over time. Individually, they have also shown significant improvements in conceptual resolution, as well as in experimental and analytic techniques. More recently, language research has embraced collaborations across disciplines, notably neuroscience, cognitive science, and computational linguistics and has ultimately re-defined classical ideas of language. As we move forward, the new models of language with their remarkably multifaceted constructs force a re-examination of the NIMH RDoC conceptualization of language and thus the neuroscience and genetics underlying this concept. © 2016 The Authors. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics Published by Wiley Periodicals, Inc.

What Causes Specific Language Impairment in Children?

Specific language impairment (SLI) is diagnosed when a child's language development is deficient for no obvious reason. For many years, there was a tendency to assume that SLI was caused by factors such as poor parenting, subtle brain damage around the time of birth, or transient hearing loss. Subsequently it became clear that these factors were far less important than genes in determining risk for SLI. A quest to find “the gene for SLI” was undertaken, but it soon became apparent that no single cause could account for all cases. Furthermore, although fascinating cases of SLI caused by a single mutation have been discovered, in most children the disorder has a more complex basis, with several genetic and environmental risk factors interacting. The clearest evidence for genetic effects has come from studies that diagnosed SLI using theoretically motivated measures of underlying cognitive deficits rather than conventional clinical criteria.

The interface between genetics and psychology: lessons from developmental dyslexia

Developmental dyslexia runs in families, and twin studies have confirmed that there is a substantial genetic contribution to poor reading. The way in which discoveries in molecular genetics are reported can be misleading, encouraging us to think that there are specific genes that might be used to screen for disorder. However, dyslexia is not a classic Mendelian disorder that is caused by a mutation in a single gene. Rather, like many other common disorders, it appears to involve combined effects of many genes and environmental factors, each of which has a small influence, possibly supplemented by rare variants that have larger effects but apply to only a minority of cases. Furthermore, to see clearer relationships between genotype and phenotype, we may need to move beyond the clinical category of dyslexia to look at underlying cognitive deficits that may be implicated in other neurodevelopmental disorders.

Multidisciplinary investigation links backward-speech trait and working memory through genetic mutation

Case studies of unusual traits can provide unique snapshots of the effects of modified systems. In this study, we report on an individual from a Serbian family with the ability to rapidly, accurately and voluntarily speak backwards. We consider psychological, neural and genetic correlates of this trait to identify specific relevant neural mechanisms and new molecular pathways for working memory and speech-related tasks. EEG data suggest that the effect of word reversal precedes semantic integration of visually presented backward-words, and that event-related potentials above the frontal lobe are affected by both word reversal and the maintenance of backward-words in working memory. fMRI revealed that the left fusiform gyrus may facilitate the production of backward-speech. Exome sequencing identified three novel coding variants of potential significance in the RIC3, RIPK1 and ZBED5 genes. Taken together, our data suggest that, in this individual, the ability to speak backwards is afforded by an extraordinary working memory capacity. We hypothesise that this is served by cholinergic projections from the basal forebrain to the frontal cortex and supported by visual semantic loops within the left fusiform gyrus and that these neural processes may be mediated by a genetic mutation in RIC3; a chaperone for nicotinic acetylcholine receptors.

Music Perception Influences Language Acquisition: Melodic and Rhythmic-Melodic Perception in Children with Specific Language Impairment

Language and music share many properties, with a particularly strong overlap for prosody. Prosodic cues are generally regarded as crucial for language acquisition. Previous research has indicated that children with SLI fail to make use of these cues. As processing of prosodic information involves similar skills to those required in music perception, we compared music perception skills (melodic and rhythmic-melodic perception and melody recognition) in a group of children with SLI (N = 29, five-year-olds) to two groups of controls, either of comparable age (N = 39, five-year-olds) or of age closer to the children with SLI in their language skills and about one year younger (N = 13, four-year-olds). Children with SLI performed in most tasks below their age level, closer matching the performance level of younger controls with similar language skills. These data strengthen the view of a strong relation between language acquisition and music processing. This might open a perspective for the possible use of musical material in early diagnosis of SLI and of music in SLI therapy.

Etiological Distinction of Working Memory Components in Relation to Mathematics

Working memory has been consistently associated with mathematics achievement, although the etiology of these relations remains poorly understood. The present study examined the genetic and environmental underpinnings of math story problem solving, timed calculation, and untimed calculation alongside working memory components in 12-year-old monozygotic (n = 105) and same-sex dizygotic (n = 143) twin pairs. Results indicated significant phenotypic correlation between each working memory component and all mathematics outcomes (r = 0.18 - 0.33). Additive genetic influences shared between the visuo-spatial sketchpad and mathematics achievement was significant, accounting for roughly 89% of the observed correlation. In addition, genetic covariance was found between the phonological loop and math story problem solving. In contrast, despite there being a significant observed relationship between phonological loop and timed and untimed calculation, there was no significant genetic or environmental covariance between the phonological loop and timed or untimed calculation skills. Further analyses indicated that genetic overlap between the visuo-spatial sketchpad and math story problem solving and math fluency was distinct from general genetic factors, whereas g, phonological loop, and mathematics shared generalist genes. Thus, although each working memory component was related to mathematics, the etiology of their relationships may be distinct.

Associations of HLA alleles with specific language impairment

BACKGROUND

Human leukocyte antigen (HLA) loci have been implicated in several neurodevelopmental disorders in which language is affected. However, to date, no studies have investigated the possible involvement of HLA loci in specific language impairment (SLI), a disorder that is defined primarily upon unexpected language impairment. We report association analyses of single-nucleotide polymorphisms (SNPs) and HLA types in a cohort of individuals affected by language impairment.

METHODS

We perform quantitative association analyses of three linguistic measures and case-control association analyses using both SNP data and imputed HLA types.

RESULTS

Quantitative association analyses of imputed HLA types suggested a role for the HLA-A locus in susceptibility to SLI. HLA-A A1 was associated with a measure of short-term memory (P = 0.004) and A3 with expressive language ability (P = 0.006). Parent-of-origin effects were found between HLA-B B8 and HLA-DQA1*0501 and receptive language. These alleles have a negative correlation with receptive language ability when inherited from the mother (P = 0.021, P = 0.034, respectively) but are positively correlated with the same trait when paternally inherited (P = 0.013, P = 0.029, respectively). Finally, case control analyses using imputed HLA types indicated that the DR10 allele of HLA-DRB1 was more frequent in individuals with SLI than population controls (P = 0.004, relative risk = 2.575), as has been reported for individuals with attention deficit hyperactivity disorder (ADHD).

CONCLUSION

These preliminary data provide an intriguing link to those described by previous studies of other neurodevelopmental disorders and suggest a possible role for HLA loci in language disorders.

FOXP2

The forkhead box P2 gene, designated FOXP2, is the first gene implicated in a speech and language disorder. Since its discovery, many studies have been carried out in an attempt to explain the mechanism by which it influences these characteristically human traits. This review presents the story of the discovery of the FOXP2 gene, including early studies of the phenotypic implications of a disruption in the gene. We then discuss recent investigations into the molecular function of the FOXP2 gene, including functional and gene expression studies. We conclude this review by presenting the fascinating results of recent studies of the FOXP2 ortholog in other species that are capable of vocal communication. WIREs Cogn Sci 2013, 4:547-560. doi: 10.1002/wcs.1247 This article is categorized under: Psychology > Language Neuroscience > Genes, Molecules, and Cells.

Word stress processing in specific language impairment: auditory or representational deficits?

Word stress processing has repeatedly been reported to be affected in specific language impairment (SLI) with potential consequences for various aspects of language development. However, it still remains unresolved whether word stress impairments in SLI are due to deficits in basic auditory processing or to a degraded phonological representation or both. We addressed this question examining an unselected sample of 10 children with SLI and 11 typically developing (TD) children, aged about 8 years, with respect to their basic auditory processing (duration and skewness discrimination) and phonological representation of prosodic (word stress) and segmental (consonant) contrasts. Our results show lower performance of the SLI group compared to the TD group in all tasks. Crucially, two subgroups of children with SLI emerged from our analyses: While one group was impaired in basic auditory perception, particularly affecting duration discrimination, the other showed no significant auditory processing deficits but a representational impairment.

Neurogenomics of speech and language disorders: the road ahead

Next-generation sequencing is set to transform the discovery of genes underlying neurodevelopmental disorders, and so offer important insights into the biological bases of spoken language. Success will depend on functional assessments in neuronal cell lines, animal models and humans themselves.

Memory and language in middle childhood in individuals with a history of specific language impairment

This study reports on the sensitivity of sentence repetition as a marker of specific language impairment (SLI) in different subgroups of children in middle childhood and examines the role of memory and grammatical knowledge in the performance of children with and without language difficulties on this task. Eleven year old children, 197 with a history of SLI and 75 typically developing (TD) peers were administered sentence repetition, phonological short term memory (PSTM) and grammatical morphology tasks. Children with a history of SLI were divided into four subgroups: specific language impairment, non-specific language impairment, low cognition with resolved language and resolved. Performance on the sentence repetition task was significantly impaired in all four subgroups of children with a history of SLI when compared to their age peers. Regression analyses revealed grammatical knowledge was predictive of performance for TD children and children with a history of SLI. However, memory abilities were significantly predictive of sentence repetition task performance for children with a history of SLI only. Processes involved in sentence repetition are more taxing of PSTM for individuals with a history of SLI in middle childhood in a way that does not appear to be the case for TD children.

12p13.33 microdeletion including ELKS/ERC1, a new locus associated with childhood apraxia of speech

Speech sound disorders are heterogeneous conditions, and sporadic and familial cases have been described. However, monogenic inheritance explains only a small proportion of such disorders, in particular in cases with childhood apraxia of speech (CAS). Deletions of <5 Mb involving the 12p13.33 locus is one of the least commonly deleted subtelomeric regions. Only four patients have been reported with such a deletion diagnosed with fluorescence in situ hybridisation telomere analysis or array CGH. To further delineate this rare microdeletional syndrome, a French collaboration together with a search in the Decipher database allowed us to gather nine new patients with a 12p13.33 subtelomeric or interstitial rearrangement identified by array CGH. Speech delay was found in all patients, which could be defined as CAS when patients had been evaluated by a speech therapist (5/9 patients). Intellectual deficiency was found in 5/9 patients only, and often associated with psychiatric manifestations of various severity. Two such deletions were inherited from an apparently healthy parent, but reevaluation revealed abnormal speech production at least in childhood, suggesting variable expressivity. The ELKS/ERC1 gene, which encodes for a synaptic factor, is found in the smallest region of overlap. These results reinforce the hypothesis that deletions of the 12p13.33 locus may be responsible for variable phenotypes including CAS associated with neurobehavioural troubles and that the presence of CAS justifies a genetic work-up.

A specific cognitive deficit within semantic cognition across a multi-generational family

We report a study of eight members of a single family (aged 8-72 years), who all show a specific deficit in linking semantic knowledge to language. All affected members of the family had high levels of overall intelligence; however, they had profound difficulties in prose and sentence recall, listening comprehension and naming. The behavioural deficit was remarkably consistent across affected family members. Structural neuroimaging data revealed grey matter abnormalities in the left infero-temporal cortex and fusiform gyri: brain areas that have been associated with integrative semantics. This family demonstrates, to our knowledge, the first example of a heritable, highly specific abnormality affecting the interface between language and cognition in humans and has important implications for our understanding of the genetic basis of cognition.

Nonword repetition: the relative contributions of phonological short-term memory and phonological representations in children with language and reading impairment

PURPOSE

This study investigates the relative contributions of phonological short-term memory and phonological representations to nonword repetition (NWR). This was evaluated in children with specific language impairment (SLI) and/or reading impairment (RI); it was also studied from a developmental perspective by comparing 2 groups of typically developing (TD) children who differed in age.

METHOD

NWR, digit span, vocabulary, and word and nonword discrimination were tested in 2 groups of TD children: one group matched on chronological age (CA TD group: n = 41, mean age = 7;8 [months;years]), and one language age-matched control group (LA TD group: n = 16, mean age = 5;8). Also, 10 children with SLI, 14 children with RI, and 23 children with SLI and RI (hereafter, SLI + RI) participated and were matched to the age of the CA TD group.

RESULTS

For the TD children, NWR was predicted by discrimination, digit span, and age. The interaction between discrimination ability and age was also significant. Children with SLI + RI were significantly impaired on NWR compared with all other groups. A regression analysis, including the CA TD group and the children with SLI and/or RI, showed that digit span, discrimination ability, and group (SLI + RI) contributed significantly to NWR.

CONCLUSIONS

Phonological short-term memory and phonological representations both significantly contribute to NWR. The predictive strength of the quality of phonological representations changes during development.

Dissection of genetic associations with language-related traits in population-based cohorts

Recent advances in the field of language-related disorders have led to the identification of candidate genes for specific language impairment (SLI) and dyslexia. Replication studies have been conducted in independent samples including population-based cohorts, which can be characterised for a large number of relevant cognitive measures. The availability of a wide range of phenotypes allows us to not only identify the most suitable traits for replication of genetic association but also to refine the associated cognitive trait. In addition, it is possible to test for pleiotropic effects across multiple phenotypes which could explain the extensive comorbidity observed across SLI, dyslexia and other neurodevelopmental disorders. The availability of genome-wide genotype data for such cohorts will facilitate this kind of analysis but important issues, such as multiple test corrections, have to be taken into account considering that small effect sizes are expected to underlie such associations.

Impairment in non-word repetition: a marker for language impairment or reading impairment?

AIM

A deficit in non-word repetition (NWR), a measure of short-term phonological memory proposed as a marker for language impairment, is found not only in language impairment but also in reading impairment. We evaluated the strength of association between language impairment and reading impairment in children with current, past, and no language impairment and assessed any differential impairment of NWR, compared with two other tests of verbal memory in children with language impairment with and without reading impairment.

METHOD

Our sample comprised children aged 6-16y 11mo participating in a study of the genetics of language impairment: 78 children from 68 families (53 males, 25 females) with current language impairment (C-LI), compared with their 74 siblings: 25 children (18 males, seven females) with a past history of language impairment and 49 children (27 males, 22 females) who had never had a language impairment. The tests used were the Clinical Evaluation of Language Fundamentals (CELF III), the Children's Test of Non-word Repetition (CN-Rep), the Wide Range Assessment of Memory and Learning (WRAML) verbal memory index, the Wechsler Intelligence Scale for Children-III (WISC-III) digit span, and the Wechsler Objective Reading Dimensions (WORD(UK) ).

RESULTS

Reading impairment was present in two-thirds of the children with current language impairment. NWR deficits were significantly worse in children with language impairment who had reading impairment in reading decoding (p=0.007 and 0.004 - average group compared with borderline and definitely impaired groups respectively) or spelling (p=0.002 and 0.005 - average group compared with borderline and severely impaired groups respectively) (not correlated with severity of language impairment) but not comprehension impairment. In contrast, WISC digit span and WRAML verbal memory were impaired in all children with language impairment and did not differentiate those who also had reading impairment.

INTERPRETATION

We suggest that current NWR ability may be a marker of a process specifically underlying language impairment, co-occurring with reading impairment involving reading decoding and spelling, rather than a generic correlate of language impairment. Other verbal memory deficits appear to be pervasive in children with language impairment.

Replication of CNTNAP2 association with nonword repetition and support for FOXP2 association with timed reading and motor activities in a dyslexia family sample

Two functionally related genes, FOXP2 and CNTNAP2, influence language abilities in families with rare syndromic and common nonsyndromic forms of impaired language, respectively. We investigated whether these genes are associated with component phenotypes of dyslexia and measures of sequential motor ability. Quantitative transmission disequilibrium testing (QTDT) and linear association modeling were used to evaluate associations with measures of phonological memory (nonword repetition, NWR), expressive language (sentence repetition), reading (real word reading efficiency, RWRE; word attack, WATT), and timed sequential motor activities (rapid alternating place of articulation, RAPA; finger succession in the dominant hand, FS-D) in 188 family trios with a child with dyslexia. Consistent with a prior study of language impairment, QTDT in dyslexia showed evidence of CNTNAP2 single nucleotide polymorphism (SNP) association with NWR. For FOXP2, we provide the first evidence for SNP association with component phenotypes of dyslexia, specifically NWR and RWRE but not WATT. In addition, FOXP2 SNP associations with both RAPA and FS-D were observed. Our results confirm the role of CNTNAP2 in NWR in a dyslexia sample and motivate new questions about the effects of FOXP2 in neurodevelopmental disorders.

Investigation of dyslexia and SLI risk variants in reading- and language-impaired subjects

Dyslexia (or reading disability) and specific language impairment (or SLI) are common childhood disorders that show considerable co-morbidity and diagnostic overlaps and have been suggested to share some genetic aetiology. Recently, genetic risk variants have been identified for SLI and dyslexia enabling the direct evaluation of possible shared genetic influences between these disorders. In this study we investigate the role of variants in these genes (namely MRPL19/C20RF3, ROBO1, DCDC2, KIAA0319, DYX1C1, CNTNAP2, ATP2C2 and CMIP) in the aetiology of SLI and dyslexia. We perform case-control and quantitative association analyses using measures of oral and written language skills in samples of SLI and dyslexic families and cases. We replicate association between KIAA0319 and DCDC2 and dyslexia and provide evidence to support a role for KIAA0319 in oral language ability. In addition, we find association between reading-related measures and variants in CNTNAP2 and CMIP in the SLI families.

Social and attention factors during infancy and the later emergence of autism characteristics

Characteristic features of autism include atypical social perception and social-communication skills, and atypical visual attention, alongside rigid and repetitive thinking and behavior. Debate has focused on whether the later emergence of atypical social skills is a consequence of attention problems early in life, or, conversely, whether early social deficits have knock-on consequences for the later development of attention skills. We investigated this question based on evidence from infants at familial risk for a later diagnosis of autism by virtue of being younger siblings of children with a diagnosis. Around 9months, at-risk siblings differed as a group from controls, both in measures of social perception and inhibitory control. We present preliminary data from an ongoing longitudinal research program, suggesting clear associations between some of these infant measures and autism-related characteristics at 3years. We discuss the findings in terms of the emergent nature of autism as a result of complex developmental interactions among brain networks.

Investigation of dyslexia and SLI risk variants in reading- and language-impaired subjects

Dyslexia (or reading disability) and specific language impairment (or SLI) are common childhood disorders that show considerable co-morbidity and diagnostic overlaps and have been suggested to share some genetic aetiology. Recently, genetic risk variants have been identified for SLI and dyslexia enabling the direct evaluation of possible shared genetic influences between these disorders. In this study we investigate the role of variants in these genes (namely MRPL19/C20RF3, ROBO1, DCDC2, KIAA0319, DYX1C1, CNTNAP2, ATP2C2 and CMIP) in the aetiology of SLI and dyslexia. We perform case-control and quantitative association analyses using measures of oral and written language skills in samples of SLI and dyslexic families and cases. We replicate association between KIAA0319 and DCDC2 and dyslexia and provide evidence to support a role for KIAA0319 in oral language ability. In addition, we find association between reading-related measures and variants in CNTNAP2 and CMIP in the SLI families.

Syllable deletion in spontaneous speech of children with specific language impairment

BACKGROUND

syllable deletion (SD) frequently occurs in Specific Language Impairment and can indicate a deviant factor in the phonologic acquisition process of these subjects.

AIM

to verify the occurrence of SD in the spontaneous speech of children with SLI and to verify the influence of word extension and syllable stress in this process.

METHODS

participants were 27 children with SLI, aged between 3:0 and 5:11 years, in a weekly speech treatment, who presented 50% of correct answers in specific phonology assessment tasks or who presented speech intelligibility within levels that allowed assessment through spontaneous speech. Speech samples were obtained during a play interaction situation between the researcher and the child and through speech elicited by the presentation of a picture. The occurrence of SD was analyzed considering the following parameters: extension of the produced words, preference for stressed or unstressed syllables, position of the syllable within the word were SD occurred.

RESULTS

there was a preference for the production of dissyllabic words (X2 = 72,49; p < 0,001); the occurrence of SD was significantly higher in polysyllabic words (X2 = 11,22; p < 0,004) and on initial syllables (X2 = 34,99; p < 0,001). Unstressed syllables were more often reduced (Z= -5.79, p <0001).

CONCLUSION

the preference for the production of dissyllabic words reassures the difficulty of these children with complex syllabic structures and, in part, explains their spontaneous speech unintelligibility. The predominance of unstressed syllable deletion indicates the preference for producing the nucleus of words, where emphasis is given to the stressed syllable during language expression.

Increasing genotype-phenotype model determinism: application to bivariate reading/language traits and epistatic interactions in language-impaired families

While advances in network and pathway analysis have flourished in the era of genome-wide association analysis, understanding the genetic mechanism of individual loci on phenotypes is still readily accomplished using genetic modeling approaches. Here, we demonstrate two novel genotype-phenotype models implemented in a flexible genetic modeling platform. The examples come from analysis of families with specific language impairment (SLI), a failure to develop normal language without explanatory factors such as low IQ or inadequate environment. In previous genome-wide studies, we observed strong evidence for linkage to 13q21 with a reading phenotype in language-impaired families. First, we elucidate the genetic architecture of reading impairment and quantitative language variation in our samples using a bivariate analysis of reading impairment in affected individuals jointly with language quantitative phenotypes in unaffected individuals. This analysis largely recapitulates the baseline analysis using the categorical trait data (posterior probability of linkage (PPL) = 80%), indicating that our reading impairment phenotype captured poor readers who also have low language ability. Second, we performed epistasis analysis using a functional coding variant in the brain-derived neurotrophic factor (BDNF) gene previously associated with reduced performance on working memory tasks. Modeling epistasis doubled the evidence on 13q21 and raised the PPL to 99.9%, indicating that BDNF and 13q21 susceptibility alleles are jointly part of the genetic architecture of SLI. These analyses provide possible mechanistic insights for further cognitive neuroscience studies based on the models developed herein.

Memory impairment in children with language impairment

AIM

The aim of this study was to assess whether any memory impairment co-occurring with language impairment is global, affecting both verbal and visual domains, or domain specific.

METHOD

Visual and verbal memory, learning, and processing speed were assessed in children aged 6 years to 16 years 11 months (mean 9 y 9 m, SD 2 y 6 mo) with current, resolved, and no language impairment using the Wide Range Assessment of Memory and Learning (WRAML), a standardized memory and learning test for children, and the Children's Test of Non-Word Repetition (CNRep), a test of phonological short-term memory. Fifty-one children (38 males, 13 females) with current speech and language impairment from 49 families were compared with 13 siblings (11 males, 2 females) with a past history of language impairment and 26 (15 males, 11 females) who had never had language impairment.

RESULTS

Children with current language impairment showed impairment in all verbal memory measures compared with children who had never had language impairment, and these impairments were still evident in children with a past history of learning impairment. Visual memory and learning were not impaired compared with children who had never had language impairment. The severity of verbal memory impairment correlated with the degree of language impairment.

INTERPRETATION

We concluded that in language impairment there is domain specificity of memory impairment affecting verbal processing.

Preschool speech, language skills, and reading at 7, 9, and 10 years: etiology of the relationship

PURPOSE

To examine the etiology of the relationship between preschool speech and language, and later reading skills.

METHOD

One thousand six hundred seventy-two children from the Twins Early Development Study (B. R. Oliver & R. Plomin, 2007) were given a comprehensive speech and language assessment at 4(1/2) years. Reading was assessed at 7, 9, and 10 years. Twin analyses were applied to the data to assess the contributions of genetic and environmental factors to the longitudinal relationships between speech and reading, and language and reading.

RESULTS

Phenotypically, there is a moderate and stable relationship between 4(1/2)-year speech and language scores and reading at 7, 9, and 10 years. Etiologically, at the individual-differences level, both genetic and shared environmental factors contribute to the links between language skills and reading. By contrast, genetic factors account for most of the relationship between early speech and later reading. At the extremes, there appears to be an even stronger role for genetic factors in accounting for the prediction from early speech and language impairments to later reading outcome.

CONCLUSION

Both genetic and environmental factors contribute to the relationship between early language skills and reading, whereas genetic factors play a dominant role in the relationship between early speech and reading.