Natalia Rakhlin

The Language Phenotype of a Small Geographically Isolated Russian-speaking Population: Implications for Genetic and Clinical Studies of Developmental Language Disorder

This article describes the results of an epidemiological study of developmental language disorder (DLD) in an isolated rural Russian population. We report an atypically high prevalence of DLD across all age groups when contrasted with a comparison population. The results are corroborated by a set of comparisons of school-aged children from the target population with their age peers and mean length of utterance matches from the comparison population. We also investigate the relationship between nonverbal cognition, verbal working memory, and expressive language performance in the population, and find statistically significant but small effect sizes. Finally, we describe the complex and heterogeneous structure of the phenotype in the population along with patterns of its vertical transmission on the basis of the exemplar pedigrees, and discuss the implications of our findings for genetic and clinical studies of DLD.

Genome-Wide Association and Exome Sequencing Study of Language Disorder in an Isolated Population

BACKGROUND AND OBJECTIVE: Developmental language disorder (DLD) is a highly prevalent neurodevelopmental disorder associated with negative outcomes in different domains; the etiology of DLD is unknown. To investigate the genetic underpinnings of DLD, we performed genome-wide association and whole exome sequencing studies in a geographically isolated population with a substantially elevated prevalence of the disorder (ie, the AZ sample). METHODS: DNA samples were collected from 359 individuals for the genome-wide association study and from 12 severely affected individuals for whole exome sequencing. Multifaceted phenotypes, representing major domains of expressive language functioning, were derived from collected speech samples. RESULTS: Gene-based analyses revealed a significant association between SETBP1 and complexity of linguistic output (P = 5.47 × 10−7). The analysis of exome variants revealed coding sequence variants in 14 genes, most of which play a role in neural development. Targeted enrichment analysis implicated myocyte enhancer factor–2 (MEF2)-regulated genes in DLD in the AZ population. The main findings were successfully replicated in an independent cohort of children at risk for related disorders (n = 372). CONCLUSIONS: MEF2-regulated pathways were identified as potential candidate pathways in the etiology of DLD. Several genes (including the candidate SETBP1 and other MEF2-related genes) seem to jointly influence certain, but not all, facets of the DLD phenotype. Even when genetic and environmental diversity is reduced, DLD is best conceptualized as etiologically complex. Future research should establish whether the signals detected in the AZ population can be replicated in other samples and languages and provide further characterization of the identified pathway.

Lexical processing deficits in children with developmental language disorder: An event-related potentials study.

Lexical processing deficits in children with developmental language disorder (DLD) have been postulated to arise as sequelae of their grammatical deficits (either directly or via compensatory mechanisms) and vice versa. We examined event-related potential indices of lexical processing in children with DLD (n = 23) and their typically developing peers (n = 16) using a picture-word matching paradigm. We found that children with DLD showed markedly reduced N400 amplitudes in response both to auditorily presented words that had initial phonological overlap with the name of the pictured object and to words that were not semantically or phonologically related to the pictured object. Moreover, this reduction was related to behavioral indices of phonological and lexical but not grammatical development. We also found that children with DLD showed a depressed phonological mapping negativity component in the early time window, suggesting deficits in phonological processing or early lexical access. The results are partially consistent with the overactivation account of lexical processing deficits in DLD and point to the relative functional independence of lexical/phonological and grammatical deficits in DLD, supporting a multidimensional view of the disorder. The results also, although indirectly, support the neuroplasticity account of DLD, according to which language impairment affects brain development and shapes the specific patterns of brain responses to language stimuli.

Gender and agreement processing in children with Developmental Language Disorder

Two experiments tested whether Russian-speaking children with Developmental Language Disorder (DLD) are sensitive to gender agreement when performing a gender decision task. In Experiment 1, the presence of overt gender agreement between verbs and/or adjectival modifiers and postverbal subject nouns memory was varied. In Experiment 2, agreement violations were introduced and the targets varied between words, pseudo-words, or pseudo-words with derivational suffixes. In both experiments, children with DLD did not differ from typically developing children in their reaction time or sensitivity to agreement features. In both groups, trials with feminine gender resulted in a higher error rate. Children with DLD displayed lower overall accuracy, which was related to differences in phonological memory in both experiments. Furthermore, in Experiment 1 group differences were not maintained after phonological memory was entered as a covariate. The results are discussed with respect to various processing and linguistic theories of DLD.

Attentional But Not Pre-Attentive Neural Measures of Auditory Discrimination Are Atypical in Children With Developmental Language Disorder

We examined neural indices of pre-attentive phonological and attentional auditory discrimination in children with developmental language disorder (DLD, n = 23) and typically developing (n = 16) peers from a geographically isolated Russian-speaking population with an elevated prevalence of DLD. Pre-attentive phonological MMN components were robust and did not differ in two groups. Children with DLD showed attenuated P3 and atypically distributed P2 components in the attentional auditory discrimination task; P2 and P3 amplitudes were linked to working memory capacity, development of complex syntax, and vocabulary. The results corroborate findings of reduced processing capacity in DLD and support a multifactorial view of the disorder.

Reading-Related Skills, Reading Achievement, and Inattention: A Correlational Study

Here we investigated the psychological texture of a literacy-related disability, specific reading disability (SRD, also referred to as dyslexia), as it is manifested in Russian and defined in the Russian Federation. Specifically, we attempted to understand the emerging properties of this deficit among 96 students in grades 2 and 3 (38 girls and 58 boys, aged 7.90–10.42 years, mean = 8.87, SD = 0.56) attending a public primary school in St. Petersburg, Russia. Based on the linguistic properties of the Russian language, we designed a literacy-skills assessment battery that incorporates both internationally common (i.e., the traditional IQ-achievement discrepancy-based) and Russia-specific (i.e., typology-based) approaches to identifying reading difficulties in emergent readers. In addition, we measured children’s levels of general intelligence, inattention, and hyperactivity (i.e., the symptomatology related to attention deficit and hyperactivity disorders, ADHD). Multi-trait-multi-method methodology was employed in that data were collected both from teachers and students for multiple reading-related processes, using both self-report and maximum performance assessments. The results are interpreted in terms of the convergence (and lack of such) between the common and country/language-specific approaches to the identification of reading difficulties, and the relevance of the general level of intelligence to diagnosing specific reading difficulties in Russian and in Russia.

Language development of internationally adopted children: Adverse early experiences outweigh the age of acquisition effect.

UNLABELLED We compared English language and cognitive skills between internationally adopted children (IA; mean age at adoption=2.24, SD=1.8) and their non-adopted peers from the US reared in biological families (BF) at two time points. We also examined the relationships between outcome measures and age at initial institutionalization, length of institutionalization, and age at adoption. On measures of general language, early literacy, and non-verbal IQ, the IA group performed significantly below their age-peers reared in biological families at both time points, but the group differences disappeared on receptive vocabulary and kindergarten concept knowledge at the second time point. Furthermore, the majority of children reached normative age expectations between 1 and 2 years post-adoption on all standardized measures. Although the age at adoption, age of institutionalization, length of institutionalization, and time in the adoptive family all demonstrated significant correlations with one or more outcome measures, the negative relationship between length of institutionalization and child outcomes remained most robust after controlling for the other variables. Results point to much flexibility and resilience in childrens capacity for language acquisition as well as the potential primacy of length of institutionalization in explaining individual variation in IA childrens outcomes. LEARNING OUTCOMES (1) Readers will be able to understand the importance of pre-adoption environment on language and early literacy development in internationally adopted children. (2) Readers will be able to compare the strength of the association between the length of institutionalization and language outcomes with the strength of the association between the latter and the age at adoption. (3) Readers will be able to understand that internationally adopted children are able to reach age expectations on expressive and receptive language measures despite adverse early experiences and a replacement of their first language with an adoptive language.

Phonemic Awareness Is a More Important Predictor of Orthographic Processing Than Rapid Serial Naming: Evidence From Russian

We studied the relationship between rapid serial naming (RSN) and orthographic processing in Russian, an asymmetrically transparent orthography. Ninety-six students (M age = 13.73) completed tests of word and pseudoword reading fluency, spelling, orthographic choice, phonological choice, phoneme awareness (PA), and RSN. PA was a better predictor of orthographic skills and pseudoword reading accuracy than RSN, which accounted for more variance in word and pseudoword reading fluency. Controlling for pseudoword reading fluency washed out RSN’s contribution to word reading fluency. These results extend previous findings questioning the role of RSN as an index of orthographic processing skills and support the idea that RSN taps into automaticity/efficiency of processing print-sound mappings.

Sources of Heterogeneity in Developmental Outcomes of Children With Past and Current Experiences of Institutionalization in Russia: A Four-Group Comparison.

The present study sought to compare 4 groups of age- and gender-matched children—(a) those reared in institutions for children without parental care in Russia; (b) those raised by their biological parents in Russia; (c) those adopted to the United States from Russian institutions; and (d) those born in the United States and raised by their biological parents—on indicators of cognition, language, and early learning. In addition, we aimed to compare the effects of the length of time spent in an institution, the age of initial placement in an institution, the age at adoption, and pre-institutional risk factors (i.e., prenatal substance exposure and prematurity and low birth weight) on the above-mentioned outcomes in the 2 groups of children with institutionalization experiences. Our results confirm previous reports demonstrating negative consequences of institutionalization and substantial ameliorating effects of adoption. They also underscore the complexity of the effects of institutionalization and adoption, showing that they are intertwined with the effects of pre-institutional risk factors.

Diversity of Grammars and Their Diverging Evolutionary and Processing Paths: Evidence From Functional MRI Study of Serbian

We address the puzzle of “unity in diversity” in human languages by advocating the (minimal) common denominator for the diverse expressions of transitivity across human languages, consistent with the view that early in language evolution there was a modest beginning for syntax and that this beginning provided the foundation for the further elaboration of syntactic complexity. This study reports the results of a functional MRI experiment investigating differential patterns of brain activation during processing of sentences with minimal versus fuller syntactic structures. These structural layers have been postulated to represent different stages in the evolution of syntax, potentially engaging different brain networks. We focused on the Serbian “middles,” analyzed as lacking the transitivity (vP) layer, contrasted with matched transitives, containing the transitivity layer. Our main hypothesis was that transitives will produce more activation in the syntactic (Brocas–Basal Ganglia) brain network, in comparison to more rudimentary middles. The participants (n = 14) were healthy adults (Mean age = 33.36; SD = 12.23), native speakers of Serbo-Croatian. The task consisted of reading a series of sentences (middles and transitives; n = 64) presented in blocks of 8, while being engaged in a detection of repetition task. We found that the processing of transitives, compared to middles, was associated with an increase in activation in the basal ganglia bilaterally. Although we did not find an effect in Brocas area, transitives, compared to middles, evoked greater activation in the precentral gyrus (BA 6), proposed to be part of the “Brocas complex.” Our results add to the previous findings that Brocas area is not the sole center for syntactic processing, but rather is part of a larger circuit that involves subcortical structures. We discuss our results in the context of the recent findings concerning the gene-brain-language pathway involving mutations in FOXP2 that likely contributed to the enhancement of the frontal-striatal brain network, facilitating human capacity for complex syntax.