MRI findings in the parents and siblings of specifically language-impaired boys

Four families that include a specifically language-impaired (SLI) boy were studied to test the hypothesis that developmental language disorders are biologically transmittable. A majority of the parents of the SLI boys had experienced communication difficulty (i.e., difficulty with speech, language, or academic skills) as children. Evidence of communication difficulty was paired on an individual basis with neuroanatomical data obtained through quantitative analysis of magnetic resonance imaging scans. Atypical perisylvian asymmetries were documented in a majority of the parents and were frequently associated with a history of communication difficulty. Atypical perisylvian asymmetries and disordered language skills were also documented for siblings of SLI boys. These findings suggest that atypical perisylvian asymmetries reflect a transmittable, biological factor that places some families at risk for language impairment.     

Cognitive Neuropsychology and Developmental Disorders: Uncomfortable Bedfellows

Cognitive neuropsychology provides a theoretical framework and methods that can be of value in the study of developmental disorders, but the "dissociation" logic at the centre of this approach is not well suited to the developmental context. This is illustrated with examples from specific language impairment. Within the developing language system there is ample evidence for interaction between levels of representation, with modularity emerging in the course of development. This means that one typically is seeking to explain a complex pattern of associated impairments, rather than highly selective deficits. For instance, a selective impairment in auditory processing can have repercussions through the language system and may lead to distinctive syntactic deficits that are seen in written as well as spoken language. Changes in the nature of representations and in the relationships between components of a developing system mean that cross-sectional data at a single point in development may be misleading indicators of the primary deficit. Furthermore, traditional cognitive neuropsychology places a disproportionate emphasis on representational (competence) deficits, with processing (performance) deficits being relatively neglected. Methods for distinguishing these two kinds of impairment are discussed, as well as other approaches for elucidating the underlying nature of developmental disorders.     

Mechanisms of developmental regression in autism and the broader phenotype: a neural network modeling approach

Loss of previously established behaviors in early childhood constitutes a markedly atypical developmental trajectory. It is found almost uniquely in autism and its cause is currently unknown (Baird et al., 2008). We present an artificial neural network model of developmental regression, exploring the hypothesis that regression is caused by overaggressive synaptic pruning and identifying the mechanisms involved. We used a novel population-modeling technique to investigate developmental deficits, in which both neurocomputational parameters and the learning environment were varied across a large number of simulated individuals. Regression was generated by the atypical setting of a single pruning-related parameter. We observed a probabilistic relationship between the atypical pruning parameter and the presence of regression, as well as variability in the onset, severity, behavioral specificity, and recovery from regression. Other neurocomputational parameters that varied across the population modulated the risk that an individual would show regression. We considered a further hypothesis that behavioral regression may index an underlying anomaly characterizing the broader autism phenotype. If this is the case, we show how the model also accounts for several additional findings: shared gene variants between autism and language impairment (Vernes et al., 2008); larger brain size in autism but only in early development (Redcay & Courchesne, 2005); and the possibility of quasi-autism, caused by extreme environmental deprivation (Rutter et al., 1999). We make a novel prediction that the earliest developmental symptoms in the emergence of autism should be sensory and motor rather than social and review empirical data offering preliminary support for this prediction.     

Procedural learning across the lifespan: A systematic review with implications for atypical development

This systematic review aimed to investigate procedural learning across the lifespan in typical and atypical development. Procedural learning is essential for the development of everyday skills, including language and communication skills. Although procedural learning efficiency has been extensively studied, there is no consensus yet on potential procedural learning changes during development and ageing. Currently, three conflicting models regarding this trajectory exist: (1) a model of age invariance; (2a) a model with a peak in young adulthood; and (2b) a model with a plateau in childhood followed by a decline. The aims of this study were (1) to investigate this debate on procedural learning across the lifespan by systematically reviewing evidence for each model from studies using the serial reaction time task; and (2) to review procedural learning in autism spectrum disorder (ASD) and specific language impairment (SLI), two developmental disorders characterized by deficits in communication skills, in the light of these models. Our findings on typical development strongly support a model of age-related changes (Model 2a or 2b) and show that mixed findings regarding the developmental trajectory during childhood can be explained by methodological differences across studies. Applying these conclusions to systematic reviews of studies of ASD and SLI makes it clear that there is a strong need for the inclusion of multiple age groups in these clinical studies to model procedural learning in atypical development. Clinical implications of the findings are discussed. Future research should focus on the role of declarative learning in both typical and atypical development.     

Reading and Spelling Disabilities in Children with and Without a History of Early Language Delay: A Neuropsychological and Linguistic Study

Language delay is a frequent antecedent of literacy problems, and both may be linked to phonological impairment. Studies on developmental dyslexia have led to contradictory results due to the heterogeneity of the pathological samples. The present study investigated whether Italian children with dyslexia showed selective phonological processing deficits or more widespread linguistic impairment and whether these deficits were associated with previous language delay. We chose 46 children with specific reading deficits and divided them into two groups based on whether they had language delay (LD) or not (NoLD). LD and NoLD children showed similar, severe deficits in reading and spelling decoding, but only LD children showed a moderate impairment in reading comprehension. LD children were more impaired in phonological working memory and phonological fluency, as well as in semantic fluency, grammatical comprehension, and verbal IQ. These findings indicate the presence of a moderate but widespread linguistic deficit (not limited to phonological processing) in a subset of dyslexic children with previous language delay that does not generalize to all children with reading difficulties.     

MRI findings in boys with specific language impairment

Magnetic resonance imaging scans of specifically language-impaired (SLI) boys were examined to determine whether atypical cerebral findings could be documented in children whose primary deficits were in language skills. Clinical examination of the scans failed to reveal any visually obvious lesions or abnormalities. In contrast, measurement of the scans revealed atypical perisylvian asymmetries in most of these subjects. The distribution of perisylvian asymmetries in SLI subjects was significantly different from the distribution in controls (p less than .01). Measurement of other brain regions revealed that extraperisylvian areas were occasionally deviant in individual SLI subjects; but no one region was consistently deviant across the SLI group. Thus, only atypical perisylvian asymmetries were linked to the language disorder. These neuroanatomical findings suggest that a prenatal alteration of brain development underlies specific language impairment.     

自闭症谱系障碍人群词义加工的脑激活模式：基于fMRI研究的元分析

本研究筛选了11项采用功能性磁共振成像技术探究言语自闭症人群词义加工的研究, 探讨了该人群与典型人群脑激活模式的差异是否具有跨研究的稳定性。结果表明, 差异的脑激活模式稳定存在, 且表现为主要涉及左额上回的典型脑区激活不足。该结果为言语ASD人群语言加工的神经机制提供了来自词义加工的跨研究激活证据, 在明确“减弱的额叶激活”这一稳定差异表现的基础上, 强调了针对不同语言加工任务开展元分析研究的必要性。     

Asynchronous language acquisition in developmental dysphasia

A longitudinal study was conducted to document and compare evolution of children with linguistic acquisition impairment. To determine whether development of the analytic mechanisms underlying linguistic processing occured in similar fashion, two children with mixed developmental dysphasia were assessed from 4 to 5:6 years of age with psycholinguistic tests at 6-months interval. Spontaneous speech and language production (consonant repertory in initial word position, MLU, and lexical diversity) were investigated in a standardized symbolic play context. The phonologic and lexico-morphologic evolution analyses revealed a marked improvement in motor control of phonology and in the application of morphosyntaxic rules in child 1, whereas child 2 was still impaired in phonology and morphosyntax. The singular developmental changes in spontaneous speech results indicate dynamic relationships between various language production facets and variability in the kind of deficit and lexical automation presented by these children. These contrasts in the evolution of language production profiles between child 1 and child 2 also underline the importance of longitudinal studies in the analysis of the atypical linguistic processing paths used by children with developmental dysphasia.     

Variability in the anatomy of the planum temporale and posterior ascending ramus: do right- and left handers differ?

The anatomy of the planum temporale (PT) and posterior ascending ramus (PAR) was studied in vivo in 67 healthy right- and left-handed adults using MRI-based morphometry. The left PT was significantly larger than the right, and there was a weakly significant effect of the right PAR larger than the left. A leftward PT asymmetry was found in 72%, and a rightward PAR asymmetry was found in 64% of the sample. The "typical" configuration of a larger left PT and larger right PAR co-occurred in 56% of the subjects studied, which was only slightly more often than predicted by chance. Eight of 67 subjects had "reversed" PT and PAR asymmetries, with consistent left and mixed handers over-represented in this group. Right PAR size was the only variable that predicted writing hand, and left PT size was the only measure that differed by sex. The left PT was expanded relative to the left PAR in 93% of the sample, suggesting that this configuration may be developmentally regulated and may be a critical substrate for the development of language. These findings demonstrate that important relationships exist between hand preference, and the anatomy of posterior cortical language areas.     

Atypical development of language and social communication in toddlers with Williams syndrome

Williams syndrome (WS) is a genetic disorder which results in an uneven cognitive profile. Despite superior language compared to other syndromes in the phenotypic outcome, toddlers with WS are as delayed in their language onset and early linguistic development as are toddlers with other syndromes. The cause of this delay in WS is as yet unknown. In a series of experiments, we examined whether atypical socio‐interactive precursors to language could contribute to the explanation of the late language onset and atypical developmental pathways observed in WS. Experiment 1 showed that despite superficially good social skills, toddlers with WS were only proficient at dyadic interaction. They were impaired in triadic interaction, essential for the referential uses of language, and showed none of the correlations between socio‐interactive markers and language seen in the typical controls. Experiment 2 focused on the comprehension and production of referential pointing. Again, the WS group was impaired, despite vocabulary levels higher than those of typically developing controls. Finally, Experiment 3 examined fine motor skills. The WS lack of pointing could not be explained in terms of motor impairments, since the WS toddlers were proficient at fine motor control, such as the pincer grip. Overall, our data indicate that the early stages of WS language follow an atypical pathway. The findings challenge the frequent claims in the literature that individuals with Williams syndrome have preserved linguistic and social skills.     

The influence of vestibular system and fetal presentation on handedness,cognitive and motor development: A comparison between cephalic and breech presentation

Genetics are undoubtedly implicated in the ontogenesis of laterality. Nonetheless, environmental factors, such as the intrauterine environment, may also play a role in the development of functional and behavioral lateralization. The aim of this study was to test the Left-Otolithic Dominance Theory (LODT; Previc, 1991) by investigating a hypothetical developmental pattern where it is assumed that a breech presentation, which is putatively associated with a dysfunctional and weakly lateralized vestibular system, can lead to weak handedness and atypical development associated with language and motor difficulties. We used the ALSPAC cohort of children from 7 to 10 years of age to conduct our investigation. Our results failed to show an association between the vestibular system and fetal presentation, nor any influence of the latter on hand preference, hand performance, or language and motor development. Bayesian statistical analyses supported these findings. Contrary to our LODT-derived hypotheses, this study offers evidence that fetal presentation does not influence the vestibular system's lateralization and seems to be a poor indicator for handedness. Nonetheless, we found that another non-genetic factor, prematurity, could lead to atypical development of handedness.     

The relationship between spoken language and speech and nonspeech processing in children with autism: a magnetic event‐related field study

It has been proposed that language impairments in children with Autism Spectrum Disorders (ASD) stem from atypical neural processing of speech and/or nonspeech sounds. However, the strength of this proposal is compromised by the unreliable outcomes of previous studies of speech and nonspeech processing in ASD. The aim of this study was to determine whether there was an association between poor spoken language and atypical event‐related field (ERF) responses to speech and nonspeech sounds in children with ASD (n = 14) and controls (n = 18). Data from this developmental population (ages 6–14) were analysed using a novel combination of methods to maximize the reliability of our findings while taking into consideration the heterogeneity of the ASD population. The results showed that poor spoken language scores were associated with atypical left hemisphere brain responses (200 to 400 ms) to both speech and nonspeech in the ASD group. These data support the idea that some children with ASD may have an immature auditory cortex that affects their ability to process both speech and nonspeech sounds. Their poor speech processing may impair their ability to process the speech of other people, and hence reduce their ability to learn the phonology, syntax, and semantics of their native language.     

Atypicalities in Cortical Structure, Handedness, and Functional Lateralization for Language in Autism Spectrum Disorders

Language is typically a highly lateralized function, with atypically reduced or reversed lateralization linked to language impairments. Given the diagnostic and prognostic role of impaired language for autism spectrum disorders (ASDs), this paper reviews the growing body of literature that examines patterns of lateralization in individuals with ASDs. Including research from structural and functional imaging paradigms, and behavioral evidence from investigations of handedness, the review confirms that atypical lateralization is common in people with ASDs. The evidence indicates reduced structural asymmetry in fronto-temporal language regions, attenuated functional activation in response to language and pre-linguistic stimuli, and more ambiguous (mixed) hand preferences, in individuals with ASDs. Critically, the evidence emphasizes an intimate relationship between atypical lateralization and language impairment, with more atypical asymmetries linked to more substantive language impairment. Such evidence highlights opportunities for the identification of structural and functional biomarkers of ASDs, affording the potential for earlier diagnosis and intervention implementation.     

A Grammatical Specific Language Impairment in Children: An Autosomal Dominant Inheritance?

The aim of this study is to provide further characterization of a subgroup of so-called “Grammatical specific language-impaired (SLI)” children. The Grammatical SLI children have a persistent and disproportionate impairment in grammatical comprehension and expression of language. Previous research has indicated that their language impairment may be characterized by a domain-specific and modular language deficit. This study provides an initial investigation as to whether there is a genetic basis underlying their disorder as has been found for other forms of SLI and for SLI in general. The incidence of familial aggregation of language impairment was investigated in 12 Grammatical SLI children (aged 9:3 to 12:10). A familial language impairment (LI) history was classified as positive if one or more of the probands' relatives had a history of a speech/language or reading/writing problem which required speech therapy or any other form of remedial help. Case history information provided an initial indication that the Grammatical SLI children had a significantly higher incidence of a positive familial LI history than could be expected by chance. A questionnaire provided evidence of a positive LI history in the first-degree relatives of the SLI probands and 49 normally developing control probands. The SLI probands had a clearly and significantly higher incidence of a positive familial LI history than the control probands (77.8 vs. 28.5%, respectively). The results are consistent with a genetic basis underlying Grammatical SLI. The pattern of impairment in the SLI probands' relatives is consistent with an autosomal dominant genetic inheritance. In contrast to the control probands, the SLI probands' impaired relatives did not show a male gender bias. Thus, the gene does not appear to be sex-linked. The data indicate that further research is warranted to investigate the nature of the LI in the relatives of the Grammatical SLI probands and the genetic characteristics of this subgroup. The implications for the biological, domain-specific, and modular bases to language are discussed.     

Commentary: causal processes leading to antisocial behavior

Conceptual, and empirical, questions are raised regarding the notion that physical aggression is the main individual risk factor for antisocial behavior, that language impairment also constitutes a risk factor, the meaning of the male preponderance for antisocial behavior, the findings on environmentally mediated risk; the role of biosocial interplay; social context effects; the construct of antisocial behavior, developmental trends; processing of experiences; and transactional effects. The main blocks to using research to develop policy are the lack of evidence on (a) the mediators of the causal processes, (b) what is needed to bring about change, (c) ways to ensure that individuals who need interventions actually receive them, and (d) differences in levels of antisocial behavior.     

Comprehension and expression of affect in language-impaired children

Eight children with developmental language impairment (LI) and eight age-, sex-, socioeconomic-status-, and I.Q.-matched controls were given tests of comprehension and expression of affective intent in spoken language and through facial expression. The LI children performed significantly more poorly than did controls in both comprehension and spontaneous expression of vocal affect. On tasks involving emotional facial expression, the opposite results were observed: The LI children were more dramatic in their expression of facial affect than were the controls. Children with language impairment appear to have a deficit in affective comprehension and expression that is modality-specific, i.e., limited to vocal affect. The heightened range of affective facial expression that they demonstrate may be a compensatory mechanism to offset their difficulties with vocal affect.This work was supported by grant 12-203 from the March of Dimes Birth Defects Foundation, and by NINDS grant NS22343 for the Center for the Study of the Neurological Basis of Language.     

Anomalous dominance in sibling stutterers: Evidence from CT scan asymmetries, dichotic listening, neuropsychological testing, and handedness

Two left-handed siblings with developmental stuttering are comprehensively described. The methods of study included speech and language evaluation, neurological and neuropsychological examinations, dichotic listening, auditory evoked responses, electroencephalogram, and CT scan asymmetry measurements. The data from each sibling showed evidence of anomalous cerebral dominance on many of the variables investigated. The CT scan measurements showed atypical asymmetries, especially in the occipital regions. These findings support the theory that stuttering may be related to anomalous cerebral dominance, both on functional as well as structural bases. Implications of anomalous dominance and the resultant effect of hemispheric rivalry on speech fluency are discussed.     

Speech perception and short-term memory deficits in persistent developmental speech disorder

Children with developmental speech disorders may have additional deficits in speech perception and/or short-term memory. To determine whether these are only transient developmental delays that can accompany the disorder in childhood or persist as part of the speech disorder, adults with a persistent familial speech disorder were tested on speech perception and short-term memory. Nine adults with a persistent familial developmental speech disorder without language impairment were compared with 20 controls on tasks requiring the discrimination of fine acoustic cues for word identification and on measures of verbal and nonverbal short-term memory. Significant group differences were found in the slopes of the discrimination curves for first formant transitions for word identification with stop gaps of 40 and 20 ms with effect sizes of 1.60 and 1.56. Significant group differences also occurred on tests of nonverbal rhythm and tonal memory, and verbal short-term memory with effect sizes of 2.38, 1.56, and 1.73. No group differences occurred in the use of stop gap durations for word identification. Because frequency-based speech perception and short-term verbal and nonverbal memory deficits both persisted into adulthood in the speech-impaired adults, these deficits may be involved in the persistence of speech disorders without language impairment.     

Cortical morphology associated with language function in neurofibromatosis,type I

Neurofibromatosis, type I (NF-I) is associated with verbal and nonverbal neuropsychological deficits and neuroanatomical anomalies. Few relationships between CNS abnormalities and cognitive function in this population, however, have been found. Reading disabilities and developmental language impairments in the general population have been associated with particular morphologic features in inferior frontal gyrus (IFG) and Heschl's gyrus (HG). We compared the morphology of these regions in children with NF-I and controls. Verbal skills in NF-I were related to IFG morphology, such that individuals with NF-I who showed "typical" gyral patterns in the right hemisphere performed worse across language measures than those showing an extra "atypical" gyrus. A doubling of HG in the left and right hemispheres was also significantly associated with performance on several neuropsychological measures. This is the first study to link regional gyral morphology with language function in NF-I. A possible molecular basis for the observed relationships is discussed.