Electrophysiological correlates of rapid auditory and linguistic processing in adolescents with specific language impairment

Brief tonal stimuli and spoken sentences were utilized to examine whether adolescents (aged 14;3-18;1) with specific language impairments (SLI) exhibit atypical neural activity for rapid auditory processing of non-linguistic stimuli and linguistic processing of verb-agreement and semantic constraints. Further, we examined whether the behavioral and electrophysiological indices for rapid auditory processing were correlated with those for linguistic processing. Fifteen adolescents with SLI and 15 adolescents with normal language met strict criteria for displaying consistent diagnoses from kindergarten through the eighth grade. The findings provide evidence that auditory processing for non-linguistic stimuli is atypical in a significant number of adolescents with SLI compared to peers with normal language and indicate that reduced efficiency in auditory processing in SLI is more vulnerable to rapid rates (200ms ISI) of stimuli presentation (indexed by reduced accuracy, a tendency for longer RTs, reduced N100 over right anterior sites, and reduced amplitude P300). Many adolescents with SLI displayed reduced behavioral accuracy for detecting verb-agreement violations and semantic anomalies, along with less robust P600s elicited by verb-agreement violations. The results indicate that ERPs elicited by morphosyntactic aspects of language processing are atypical in many adolescents with SLI. Additionally, correlational analyses between behavioral and electrophysiological indices of processing non-linguistic stimuli and verb-agreement violations suggest that the integrity of neural functions for auditory processing may only account for a small proportion of the variance in morphosyntactic processing in some adolescents.     

Pragmatic difficulties in children with specific language impairment. The role of mentalistic tasks

Several subjects with Specific Language Impairment (SLI) show communicative and pragmatic problems. In this study, we suggested that mentalistic comprehension tasks would help us to find a deteriorated pragmatic profile among the population with SLI. To achieve this goal, a group of participants with conventional SLI (n=11) was compared to a group of SLI with more pragmatic problems (n=9) and their respective control group with typically developed language (n=13), of ages between 4 and 7 years. Results revealed that all the groups were able to attribute mental states in tasks where the context was structured. However, the subjects with predominant pragmatic SLI showed poorer performance than those with conventional SLI when tasks were communicative-oriented and they needed to process non-explicit information from the context. These findings suggest that it is possible to isolate a SLI subtype with more pragmatic problems and also that we can use mentalistic tasks to assess these difficulties more accurately.     

The effects of presentation and content on syllogistic reasoning by children with and without specific language impairment

This study examines performance at a syllogistic reasoning task for a group of children (age 10 years) with specific language impairment (SLI) along with age- and language-matched controls. The syllogisms were presented either verbally or verbally/pictorially, and contained two types of item: imaginary versus real, both intended not to evoke strong beliefs. Children with SLI performed worse than age-matched controls, and equivalently to language-matched controls. Patterns of performance indicate this may be due to cognitive ability deficits rather than specific language deficits. For all groups, pictorial presentation interfered with reasoning processes. It is suggested that, for syllogisms, this pictorial information contextualises the interpretation of the task, and that in turn either raises working memory load or evokes belief bias. Additionally, these results suggest that caution should be exhibited before using visual aids to help children with SLI in the classroom.     

What Causes Specific Language Impairment in Children?

ABSTRACT— 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.     

Brainstem correlates of temporal auditory processing in children with specific language impairment

Deficits in identification and discrimination of sounds with short inter-stimulus intervals or short formant transitions in children with specific language impairment (SLI) have been taken to reflect an underlying temporal auditory processing deficit. Using the sustained frequency following response (FFR) and the onset auditory brainstem responses (ABR) we evaluated if children with SLI show abnormalities at the brainstem level consistent with a temporal processing deficit. To this end, the neural encoding of tonal sweeps, as reflected in the FFR, for different rates of frequency change, and the effects of reducing inter-stimulus interval on the ABR components were evaluated in 10 4–11-year-old SLI children and their age-matched controls. Results for the SLI group showed degraded FFR phase-locked neural activity that failed to faithfully track the frequency change presented in the tonal sweeps, particularly at the faster sweep rates. SLI children also showed longer latencies for waves III and V of the ABR and a greater prolongation of wave III at high stimulus rates (>30/sec), suggesting greater susceptibility to neural adaptation. These results taken together appear to suggest a disruption in the temporal pattern of phase-locked neural activity necessary to encode rapid frequency change and an increased susceptibility to desynchronizing factors related to faster rates of stimulus presentation in children with SLI.     

Atypical long-latency auditory event-related potentials in a subset of children with specific language impairment

It has been proposed that specific language impairment (SLI) is the consequence of low-level abnormalities in auditory perception. However, studies of long-latency auditory ERPs in children with SLI have generated inconsistent findings. A possible reason for this inconsistency is the heterogeneity of SLI. The intraclass correlation (ICC) has been proposed as a useful statistic for evaluating heterogeneity because it allows one to compare an individual's auditory ERP with the grand average waveform from a typically developing reference group. We used this method to reanalyse auditory ERPs from a sample previously described by Uwer, Albrecht and von Suchodoletz (2002). In a subset of children with receptive SLI, there was less correspondence (i.e. lower ICC) with the normative waveform (based on the control grand average) than for typically developing children. This poorer correspondence was seen in responses to both tone and speech stimuli for the period 100-228 ms post stimulus onset. The effect was lateralized and seen at right- but not left-sided electrodes.     

Domain-specific cognitive systems: insight from Grammatical-SLI

Specific language-impairment (SLI) is a disorder of language acquisition in children who otherwise appear to be normally developing. Controversy surrounds whether SLI results from impairment to a "domain-specific" system devoted to language itself or from some more "domain-general" system. I compare these two views of SLI, and focus on three components of grammar that are good candidates for domain-specificity: syntax, morphology and phonology. I argue that the disorder is heterogeneous, and that deficits of different subgroups potentially stem from different underlying causes. Interestingly, although poor sensory or non-verbal abilities often co-occur with SLI, there is no evidence that these impairments cause the grammatical deficits found in SLI. Moreover, evidence suggests that impairment in at least one subgroup is specific to grammar.     

The attentional blink reveals sluggish attentional shifting in adolescents with specific language impairment

Rapid processing deficits have been the subject of much debate in the literature on specific language impairment (SLI). Hari and Renvall (2001) [Hari, R. & Renvall, H. (2001). Impaired processing of rapid stimulus sequences in dyslexia. Trends in cognitive sciences, 5, 525-532.] proposed that the source of this deficit can be attributed to sluggish attentional shifting abilities. That is, more time is required to shift attention between stimuli. To test this claim, 26 adolescents with SLI (divided into two subgroups to control for differences in non-verbal intelligence) and 14 controls were presented with a rapid serial visual presentation task. In this task participants were asked to detect two visual targets presented serially with distracter items with varying inter-target intervals (i.e., time difference between targets). This task was designed to elicit an attentional blink (AB). The AB describes the phenomenon whereby non-impaired individuals are less likely to report the second of two targets presented within 200-500ms of each other. After controlling for group differences in non-verbal intelligence, the SLI group was found to be significantly less accurate than the control group at successfully reporting the second target at inter-target intervals of 100, 200, 300, 400 and 800ms. The results were interpreted to suggest that adolescents with language impairments have an AB which differs from non-impaired individuals in both magnitude and duration.     

Grammaticality sensitivity in children with early focal brain injury and children with specific language impairment

Grammaticality judgments and processing times associated with violation detection were examined in typically developing children, children with focal brain lesions (FL) acquired early in life, and children with specific language impairment (SLI). Grammatical sensitivity in the FL group, while below typically developing children, was above levels seen in children with SLI. Age effects were noted with developmental changes in sensitivity extending into adolescence. Developmental delays in grammatical processing were particularly pronounced for children with SLI, who showed sensitivity levels below those of younger typically developing children. Sensitivity to agreement violations was also protracted in the SLI group providing further evidence of the vulnerability of morphology, a pattern not unlike that seen in adult aphasics. Findings for the FL group provide compelling evidence of neural and behavioral plasticity in children with early unilateral brain injury. Moreover, results from these children underscore how very different compensatory organization may be compared to profiles seen in adult aphasics who have comparable lesions. In contrast, although it was expected that the SLI children would perform below the typically developing children, the disadvantage seen with respect to the FL group suggests that the underlying pathology responsible for SLI may be more pervasive and less plastic than the focal pathology of children with early brain damage.     

Relative Clause Gap-Filling in Children with Specific Language Impairment

Children with Specific Language Impairment (SLI) have been observed to have production and perception difficulties with sentences containing long-distance dependencies, but it is unclear whether this is due to impairment in grammatical knowledge or in processing mechanisms. The current study addressed this issue by examining automatic on-line gap-filling in relative clauses, as well as off-line comprehension of the same stimulus sentences. As predicted by both knowledge impairment and processing impairment models, SLI children showed lack of immediate gap-filling after the relative clause verb, in comparison to a control group of typically developing children. However, on the off-line measure of comprehension of the same stimuli sentences, SLI children and TD children did not differ qualitatively. This finding is incompatible with knowledge impairment. We interpret the results to show that SLI children have impaired processing mechanisms (such as temporally delayed gap-filling) but are not impaired in their grammatical knowledge.     

Immature cortical responses to auditory stimuli in specific language impairment: evidence from ERPs to rapid tone sequences

Event-related potentials (ERPs) to tone pairs and single tones were measured for 16 participants with specific language impairment (SLI) and 16 age-matched controls aged from 10 to 19 years The tone pairs were separated by an inter-stimulus interval (ISI) of 20, 50 or 150 ms. The intraclass correlation (ICC) was computed for each participant between the ERP to a single tone and the ERP to the tone pair. A high ICC indicates that the brain response to a tone pair is similar to that for a single tone. ICCs were significantly higher at short than at long ISIs. At 50-ms ISI, ICCs were higher for younger than older participants. Age and ISI interacted with SLI status: ERPs of older participants with SLI differed from age-matched controls, and resembled ERPs of younger controls, consistent with a theory of immature auditory processing in SLI.     

The italian determiner system in normal acquisition, specific language impairment, and childhood aphasia

The paper presents a comparison of the development of the Italian determiner system in three different populations: normally developing children, a child recovering from childhood aphasia from the age of 3 years, 9 months, and 11 specific language impairment (SLI) children. Data from Italian normal children provide evidence for the hypothesis (1) that no prefunctional stage exists as far as the determiner system is concerned and (2) that the syntactic properties of determiners play an essential triggering role early on. The analysis of the determiner system in the aphasic child has a double interest. On the one hand, it may help to shed light on some of the intriguing questions concerning this type of disorder; on the other, it may be relevant for the discussion of the notion of agrammatism. Results of the morphosyntactic analysis reveal that, apart from timing differences, recovery from childhood aphasia shares important features with normal development. Differently from mean length of utterance (MLU)-matched normal controls and the aphasic child, SLI children omit determiners significantly more often than almost any other functional category or free morpheme. We will argue that the reasons for the SLI children's atypical behavior have to be sought in the nonaccessibility to or in the misappreciation of one fundamental syntactic property of determiners: their role as elements that assign argumenthood to nominal expressions (Szabolcsi, 1987; Longobardi, 1994).     

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.     

Developmental cognitive genetics: how psychology can inform genetics and vice versa

Developmental neuropsychology is concerned with uncovering the underlying basis of developmental disorders such as specific language impairment (SLI), developmental dyslexia, and autistic disorder. Twin and family studies indicate that genetic influences play an important part in the aetiology of all of these disorders, yet progress in identifying genes has been slow. One way forward is to cut loose from conventional clinical criteria for diagnosing disorders and to focus instead on measures of underlying cognitive mechanisms. Psychology can inform genetics by clarifying what the key dimensions are for heritable phenotypes. However, it is not a one-way street. By using genetically informative designs, one can gain insights about causal relationships between different cognitive deficits. For instance, it has been suggested that low-level auditory deficits cause phonological problems in SLI. However, a twin study showed that, although both types of deficit occur in SLI, they have quite different origins, with environmental factors more important for auditory deficit, and genes more important for deficient phonological short-term memory. Another study found that morphosyntactic deficits in SLI are also highly heritable, but have different genetic origins from impairments of phonological short-term memory. A genetic perspective shows that a search for the underlying cause of developmental disorders may be misguided, because they are complex and heterogeneous and are associated with multiple risk factors that only cause serious disability when they occur in combination.     

A comparison of working memory profiles in school-aged children with Specific Language Impairment, Attention Deficit/Hyperactivity Disorder, Comorbid SLI and ADHD and their typically developing peers

The association between specific language impairment (SLI), attention deficit/hyperactivity disorder (ADHD), and working memory (WM) was examined. WM has been implicated in language acquisition and models of ADHD; however, evidence for WM deficits in SLI and ADHD has been inconsistent. The components of Baddeley's WM model were investigated in 18 children with SLI, 16 children with ADHD, 11 children with comorbid SLI+ADHD, and 24 typically developing (TD) children. The presence of SLI resulted in deficits in more components of WM than the presence of ADHD indicating that children with SLI are more vulnerable to WM deficits than those with ADHD.     

A comparison of working memory profiles in school-aged children with Specific Language Impairment,Attention Deficit/Hyperactivity Disorder,Comorbid SLI and ADHD and their typically developing peers

The association between specific language impairment (SLI), attention deficit/hyperactivity disorder (ADHD), and working memory (WM) was examined. WM has been implicated in language acquisition and models of ADHD; however, evidence for WM deficits in SLI and ADHD has been inconsistent. The components of Baddeley's WM model were investigated in 18 children with SLI, 16 children with ADHD, 11 children with comorbid SLI+ADHD, and 24 typically developing (TD) children. The presence of SLI resulted in deficits in more components of WM than the presence of ADHD indicating that children with SLI are more vulnerable to WM deficits than those with ADHD.     

Processing of audiovisually congruent and incongruent speech in school‐age children with a history of specific language impairment: a behavioral and event‐related potentials study

Previous studies indicate that at least some aspects of audiovisual speech perception are impaired in children with specific language impairment (SLI). However, whether audiovisual processing difficulties are also present in older children with a history of this disorder is unknown. By combining electrophysiological and behavioral measures, we examined perception of both audiovisually congruent and audiovisually incongruent speech in school‐age children with a history of SLI (H‐SLI), their typically developing (TD) peers, and adults. In the first experiment, all participants watched videos of a talker articulating syllables ‘ba’, ‘da’, and ‘ga’ under three conditions – audiovisual (AV), auditory only (A), and visual only (V). The amplitude of the N1 (but not of the P2) event‐related component elicited in the AV condition was significantly reduced compared to the N1 amplitude measured from the sum of the A and V conditions in all groups of participants. Because N1 attenuation to AV speech is thought to index the degree to which facial movements predict the onset of the auditory signal, our findings suggest that this aspect of audiovisual speech perception is mature by mid‐childhood and is normal in the H‐SLI children. In the second experiment, participants watched videos of audivisually incongruent syllables created to elicit the so‐called McGurk illusion (with an auditory ‘pa’ dubbed onto a visual articulation of ‘ka’, and the expectant perception being that of ‘ta’ if audiovisual integration took place). As a group, H‐SLI children were significantly more likely than either TD children or adults to hear the McGurk syllable as ‘pa’ (in agreement with its auditory component) than as ‘ka’ (in agreement with its visual component), suggesting that susceptibility to the McGurk illusion is reduced in at least some children with a history of SLI. Taken together, the results of the two experiments argue against global audiovisual integration impairment in children with a history of SLI and suggest that, when present, audiovisual integration difficulties in this population likely stem from a later (non‐sensory) stage of processing.     

Developmental cognitive genetics: How psychology can inform genetics and vice versa

Developmental neuropsychology is concerned with uncovering the underlying basis of developmental disorders such as specific language impairment (SLI), developmental dyslexia, and autistic disorder. Twin and family studies indicate that genetic influences play an important part in the aetiology of all of these disorders, yet progress in identifying genes has been slow. One way forward is to cut loose from conventional clinical criteria for diagnosing disorders and to focus instead on measures of underlying cognitive mechanisms. Psychology can inform genetics by clarifying what the key dimensions are for heritable phenotypes. However, it is not a one-way street. By using genetically informative designs, one can gain insights about causal relationships between different cognitive deficits. For instance, it has been suggested that low-level auditory deficits cause phonological problems in SLI. However, a twin study showed that, although both types of deficit occur in SLI, they have quite different origins, with environmental factors more important for auditory deficit, and genes more important for deficient phonological short-term memory. Another study found that morphosyntactic deficits in SLI are also highly heritable, but have different genetic origins from impairments of phonological short-term memory. A genetic perspective shows that a search for the underlying cause of developmental disorders may be misguided, because they are complex and heterogeneous and are associated with multiple risk factors that only cause serious disability when they occur in combination.     

Mirror-drawing skill in children with specific language impairment: Improving generalization by incorporating variability into the practice session

This study aimed to investigate the procedural deficit hypothesis (PDH) in children with specific language impairment (SLI) by using a mirror-drawing task, a sensorimotor adaptation paradigm that does not involve sequence learning and has never before been used in SLI. A total of 30 school-aged children with SLI matched to 30 typically developing (TD) control children had to trace several figures seen only in mirror-reversed view in two practice sessions separated by a one-week interval. Two practice conditions were compared: a constant condition in which children had to trace the same figure throughout the learning trials, and a variable one in which they had to trace different figures in each trial. The results revealed a similar learning pattern between SLI and TD children in both practice conditions, suggesting that initial learning for a non-sequential procedural task is preserved in SLI. However, the children with SLI generalized the mirror-drawing skill in the same way as the TD children only if there was variability in the way the material was trained (variable practice). No significant schedule effects were observed in the control group.