Working, declarative and procedural memory in specific language impairment

According to the Procedural Deficit Hypothesis (PDH), abnormalities of brain structures underlying procedural memory largely explain the language deficits in children with specific language impairment (SLI). These abnormalities are posited to result in core deficits of procedural memory, which in turn explain the grammar problems in the disorder. The abnormalities are also likely to lead to problems with other, non-procedural functions, such as working memory, that rely at least partly on the affected brain structures. In contrast, declarative memory is expected to remain largely intact, and should play an important compensatory role for grammar. These claims were tested by examining measures of working, declarative and procedural memory in 51 children with SLI and 51 matched typically-developing (TD) children (mean age 10). Working memory was assessed with the Working Memory Test Battery for Children, declarative memory with the Children's Memory Scale, and procedural memory with a visuo-spatial Serial Reaction Time task. As compared to the TD children, the children with SLI were impaired at procedural memory, even when holding working memory constant. In contrast, they were spared at declarative memory for visual information, and at declarative memory in the verbal domain after controlling for working memory and language. Visuo-spatial short-term memory was intact, whereas verbal working memory was impaired, even when language deficits were held constant. Correlation analyses showed neither visuo-spatial nor verbal working memory was associated with either lexical or grammatical abilities in either the SLI or TD children. Declarative memory correlated with lexical abilities in both groups of children. Finally, grammatical abilities were associated with procedural memory in the TD children, but with declarative memory in the children with SLI. These findings replicate and extend previous studies of working, declarative and procedural memory in SLI. Overall, we suggest that the evidence largely supports the predictions of the PDH.     

Aspects of grammar sensitive to procedural memory deficits in children with specific language impairment

Procedural deficit hypothesis claims that language deficit in children with specific language impairment is affiliated to sequence learning problems. However, studies did not explore on aspects of grammar vulnerable to sequence learning deficits. The present study makes predictions for aspects of grammar that could be sensitive to procedural deficits based on core ideas of procedural deficit hypothesis. The hypothesis for the present study was that the grammatical operations that require greater sequencing abilities (such as inflectional operations) would be more affected in children with language impairment. Further, the influence of sequencing difficulties would be even greater in agglutinating inflectional languages. An adapted serial reaction time task for sequence learning measurements along with grammatical tasks on derivation, inflection, and sentence complexity were examined on typically developing and language impaired children. Results were in favor of procedural deficit hypothesis and its close relation to non-adjacent grammatical operations. The findings were discussed using procedural deficits, declarative compensatory mechanism, and statistical learning deficits.     

Memory consolidation in children with specific language impairment: Delayed gains and susceptibility to interference in implicit sequence learning

In this study, the time course of the procedural learning of a visuomotor sequence skill was followed over a 24-hour and a 1-week time period in children with and without specific language impairment (SLI). Two aspects of memory consolidation in implicit sequence learning were examined: the evolution of post-training gains in sequence knowledge (Experiment 1) and the susceptibility to interference (Experiment 2). In the first experiment, 18 children with SLI and 17 control children matched for sex, age, and nonverbal intelligence completed a serial reaction-time (SRT) task and were tested 24 hours and 1 week after practicing. The two groups of children attained an equal level of sequence knowledge in the training session, but the children with SLI lacked the consolidation gains displayed by the control children in the two post-training sessions. Working with a new group of children, 17 with SLI and 17 control peers, Experiment 2 examined resistance to interference by introducing a second sequence 15 min after the first training session. Similar results were obtained for the performance of both groups in the training session. However, although the performance of the control group improved in the post-training sessions, the performance of the SLI group deteriorated significantly during the consolidation phase due to the interfering sequence. These findings suggest that the consolidation phase of sequence learning is impaired in children with SLI.     

Specific language impairment is not specific to language: the procedural deficit hypothesis

Specific Language Impairment (SLI) has been explained by two broad classes of hypotheses, which posit either a deficit specific to grammar, or a non-linguistic processing impairment. Here we advance an alternative perspective. According to the Procedural Deficit Hypothesis (PDH), SLI can be largely explained by the abnormal development of brain structures that constitute the procedural memory system. This system, which is composed of a network of inter-connected structures rooted in frontal/basal-ganglia circuits, subserves the learning and execution of motor and cognitive skills. Crucially, recent evidence also implicates this system in important aspects of grammar. The PDH posits that a significant proportion of individuals with SLI suffer from abnormalities of this brain network, leading to impairments of the linguistic and non-linguistic functions that depend on it. In contrast, functions such as lexical and declarative memory, which depend on other brain structures, are expected to remain largely spared. Evidence from an in-depth retrospective examination of the literature is presented. It is argued that the data support the predictions of the PDH, and particularly implicate Broca's area within frontal cortex, and the caudate nucleus within the basal ganglia. Finally, broader implications are discussed, and predictions for future research are presented. It is argued that the PDH forms the basis of a novel and potentially productive perspective on SLI.     

Phonological memory and word learning deficits in children with specific language impairment: A role for perceptual context?

BackgroundSensitivity to perceptual context (anchoring) has been suggested to contribute to the development of both oral- and written-language skills, but studies of this idea in children have been rare.AimsTo determine whether deficient anchoring contributes to the phonological memory and word learning deficits of children with specific language impairment (SLI).Methods and procedures84 preschool children with and without SLI participated in the study. Anchoring to repeated items was evaluated in two tasks – a phonological memory task and a pseudo-word learning task.Outcomes and resultsCompared to children with typical development, children with SLI had poorer phonological memory spans and learned fewer words during the word learning task. In both tasks the poorer performance of children with SLI reflected a smaller effect of anchoring that was manifested in a smaller effect of item repetition on performance. Furthermore, across the entire sample anchoring was significantly correlated with performance in vocabulary and grammar tasks.Conclusions and implicationsThese findings are consistent with the hypothesis that anchoring contributes to language skills and that children with SLI have impaired anchoring, although further studies are required to determine the role of anchoring in language development.     

Working memory performance and executive function behaviors in young children with SLI

The present study compared the performances of young children with specific language impairment (SLI) to that of typically developing (TD) children on cognitive measures of working memory (WM) and behavioral ratings of executive functions (EF). The Automated Working Memory Assessment was administered to 58 children with SLI and 58 TD children aged 4 and 5 years. Additionally, parents completed the Behavior Rating Inventory of Executive Function – Preschool Version. The results showed the SLI group to perform significantly worse than the TD group on both cognitive and behavioral measures of WM. The deficits in WM performance were not restricted to the verbal domain, but also affected visuospatial WM. The deficits in EF behaviors included problems with inhibition, shifting, emotional control, and planning/organization. The patterns of associations between WM performance and EF behaviors differed for the SLI versus TD groups. WM performance significantly discriminated between young children with SLI and TD, with 89% of the children classified correctly. The data indicate domain general impairments in WM and problems in EF behaviors in young children with SLI. Attention should thus be paid to WM – both verbal and visuospatial – and EF in clinical practice. Implications for assessment and remediation were discussed.     

Impaired implicit sequence learning in children with developmental dyslexia

It has been proposed that an impairment of procedural memory underlies a range of linguistic, cognitive and motor impairments observed in developmental dyslexia (DD). However, studies designed to test this hypothesis using the implicit sequence learning paradigm have yielded inconsistent results. A fundamental aspect of procedural learning is that it takes place over an extended time-period that may be divided into distinct stages based on both behavioural characteristics and neural correlates of performance. Yet, no study of implicit sequence learning in children with DD has included learning stages beyond a single practice session. The present study was designed to fill this important gap by extending the investigation to include the effects of overnight consolidation as well as those of further practice on a subsequent day. The results suggest that the most pronounced procedural learning impairment in DD may emerge only after extended practice, in learning stages beyond a single practice session.     

Visual attentional engagement deficits in children with Specific Language Impairment and their role in real-time language processing

In order to become a proficient user of language, infants must detect temporal cues embedded within the noisy acoustic spectra of ongoing speech by efficient attentional engagement. According to the neuro-constructivist approach, a multi-sensory dysfunction of attentional engagement – hampering the temporal sampling of stimuli – might be responsible for language deficits typically shown in children with Specific Language Impairment (SLI). In the present study, the efficiency of visual attentional engagement was investigated in 22 children with SLI and 22 typically developing (TD) children by measuring attentional masking (AM). AM refers to impaired identification of the first of two sequentially presented masked objects (O1 and O2) in which the O1–O2 interval was manipulated. Lexical and grammatical comprehension abilities were also tested in both groups. Children with SLI showed a sluggish engagement of temporal attention, and individual differences in AM accounted for a significant percentage of unique variance in grammatical performance. Our results suggest that an attentional engagement deficit – probably linked to a dysfunction of the right fronto-parietal attentional network – might be a contributing factor in these children's language impairments.     

Visuospatial working memory in specific language impairment: A meta-analysis

We conducted a meta-analysis of the data from studies comparing visuospatial working memory (WM) in children with specific language impairment (SLI) and typically developing (TD) children. The effect sizes of 21 studies (including 32 visuospatial storage tasks and 9 visuospatial central executive (CE) tasks) were identified via computerized database searches and the reference sections of the identified studies. Meta-analyses and moderator analyses were conducted to examine the magnitude of the differences in visuospatial storage and CE, and their relation to the inclusion criteria used for SLI and the age of the children. The results showed significant effect sizes for visuospatial storage (d = 0.49) and visuospatial CE (d = 0.63), indicating deficits in both components of visuospatial WM in children with SLI. The moderator analyses showed that greater impairment in visuospatial storage was associated with more pervasive language impairment, whereas age was not significant associated with visuospatial WM. The finding of deficits in visuospatial WM suggests domain-general impairments in children with SLI. It raises questions about the language-specificity of a diagnosis of SLI. Careful attention should thus be paid to both verbal and visuospatial WM in clinical practice, and especially in those children with pervasive language impairments.     

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

Abstract

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.     

Subject relatives by children with and without SLI across different dialects of English

This study examined whether children's use of subject relative clauses differs as a function of their English dialect (African American English, AAE vs. Southern White English, SWE vs. Mainstream American English, MAE) and clinical diagnosis (specific language impairment, SLI vs. typically developing, TD). The data were spontaneous language samples from 87 AAE- and 53 SWE-speaking children, aged 3 to 6 years. Data on MAE came from previously published studies. Results were that the TD child speakers of AAE and SWE presented similar rates and types of subject relative clauses within their samples, but the rates at which they supplied the relative marker within these clauses varied from those that have been reported for TD child speakers of MAE. Nevertheless, across both AAE and SWE, the rates at which the children with SLI produced relative markers within clauses were lower than the rates of their TD peers, and these findings could not be explained by differences in the children's overall rates of non-mainstream English pattern use. These findings are consistent with studies of MAE-speaking children, and they also show across-dialect similarities in the grammatical deficits of children with SLI.     

Low-level neural auditory discrimination dysfunctions in specific language impairment—A review on mismatch negativity findings

In specific language impairment (SLI), there is a delay in the child’s oral language skills when compared with nonverbal cognitive abilities. The problems typically relate to phonological and morphological processing and word learning. This article reviews studies which have used mismatch negativity (MMN) in investigating low-level neural auditory dysfunctions in this disorder. With MMN, it is possible to tap the accuracy of neural sound discrimination and sensory memory functions. These studies have found smaller response amplitudes and longer latencies for speech and non-speech sound changes in children with SLI than in typically developing children, suggesting impaired and slow auditory discrimination in SLI. Furthermore, they suggest shortened sensory memory duration and vulnerability of the sensory memory to masking effects. Importantly, some studies reported associations between MMN parameters and language test measures. In addition, it was found that language intervention can influence the abnormal MMN in children with SLI, enhancing its amplitude. These results suggest that the MMN can shed light on the neural basis of various auditory and memory impairments in SLI, which are likely to influence speech perception.     

Developmental dyslexia and specific language impairment: distinct syntactic profiles?

Recent work exploring syntax in developmental dyslexia (DD) has identified morphosyntactic deficits, striking parallelisms between children with DD and specific language impairment (SLI). The question remains open if the underlying causes for such deficits are related to difficulties in phonology, which is affected in DD, or to working memory, as has been previously reported for SLI. We focus on the production of third person accusative clitic pronouns (ACC3) and of homophonous definite determiners in French-speaking children with DD and SLI as well as typically developing (TD) controls. If syntactic complexity modulates performance of DD children, as has already been shown for SLI, we predict children with DD to perform significantly worse on ACC3 compared to definite determiners, which are homophonous but syntactically simpler. In addition, if impairment in ACC3 stems from phonology or working memory difficulties, we expect ACC3 performance in both clinical groups to relate to performance on non-word repetition or forward/backward digit spans. We studied 2 groups of 21 children and adolescents, with DD and SLI (7–15 years) and age-matched TD controls. Results reveal significant weaknesses with ACC3 in DD and SLI groups compared to TD controls, but no difficulty for homophonous definite determiners, confirming a deficit relating specifically to syntactic complexity. As for links to phonology and working memory, a single correlation emerged between ACC3 and the backward digit span in SLI, but not in DD, suggesting different underlying sources for syntactic deficits in these populations. Clinical implications of these results are discussed.     

Exploring the boundaries of SLI: findings from morphosyntactic and story grammar analyses

The nature of morphosyntactic and story‐grammar differences were examined between children with SLI and children with language impairments that fell outside the diagnostic category for SLI solely because of their low non‐verbal cognitive abilities (LNVA). Two oral narratives were elicited from 5‐year‐old children with language impairments and age‐matched children with normally developing language. Morphosyntactic difficulties were found to be similar for children with SLI and children with LNVA. The children with SLI produced more complex stories than the children with LNVA when a complex wordless picture book was used, but not for a single scene picture stimulus. These findings challenge notions about the unique nature of SLI and, understandings of differences and similarities with other language impairments.     

Sleep-dependent motor sequence memory consolidation in individuals with periodic limb movements

Periodic limb movements (PLMs) during sleep increase with age and are associated with striatal neurodegeneration and dopamine deficiency. Limb movements are often associated with disruptions to non-rapid eye movement (NREM) sleep. Motor skill memory consolidation recruits the striatum, and learning-dependent striatal activation is associated with NREM sleep. Therefore, we investigated whether de novo individuals who significantly experience elevated levels of PLMs but have not been formally diagnosed with periodic limb movement disorder had learning and sleep-related memory deficits and whether these deficits were related to sleep quality and symptom severity.In total, 14 adults with significantly elevated PLMs (PLM condition), 15 age-matched controls (CTRL), and 14 age-matched “disturbed” sleep (through induced leg movements) controls (CTRL-ES) participated. The participants were trained (PM) and retested (AM) on procedural motor sequence learning (MSL) and declarative paired associates memory tasks.Baseline sleep quality was significantly worse in PLM than in CTRL. Despite the continued presence of PLMs in the PLM condition on the experimental night, remarkably, sleep quality improved and arousals decreased, vs. baseline, and did not differ from CTRL. MSL was significantly slower in the PLM condition than in CTRL at training but surprisingly exhibited overnight performance gains, which correlated with reduced arousals. As predicted, CTRL but not CTRL-ES had overnight gains in MSL. Taken together, this suggests that in the PLM condition, sleep quality was normalized following MSL, where they derived the same benefit of sleep to procedural memory consolidation as in CTRL. Sleep did not benefit declarative memory.Although preliminary, these results suggest that MSL in individuals with PLMs may provide a benefit to sleep, which in turn may benefit memory consolidation.     

Novel-word learning deficits in Mandarin-speaking preschool children with specific language impairments

Children with SLI exhibit overall deficits in novel word learning compared to their age-matched peers. However, the manifestation of the word learning difficulty in SLI was not consistent across tasks and the factors affecting the learning performance were not yet determined. Our aim is to examine the extent of word learning difficulties in Mandarin-speaking preschool children with SLI, and to explore the potent influence of existing lexical knowledge on to the word learning process. Preschool children with SLI (n = 37) and typical language development (n = 33) were exposed to novel words for unfamiliar objects embedded in stories. Word learning tasks including the initial mapping and short-term repetitive learning were designed. Results revealed that Mandarin-speaking preschool children with SLI performed as well as their age-peers in the initial form-meaning mapping task. Their word learning difficulty was only evidently shown in the short-term repetitive learning task under a production demand, and their learning speed was slower than the control group. Children with SLI learned the novel words with a semantic head better in both the initial mapping and repetitive learning tasks. Moderate correlations between stand word learning performances and scores on standardized vocabulary were found after controlling for children's age and nonverbal IQ. The results suggested that the word learning difficulty in children with SLI occurred in the process of establishing a robust phonological representation at the beginning stage of word learning. Also, implicit compound knowledge is applied to aid word learning process for children with and without SLI. We also provide the empirical data to validate the relationship between preschool children's word learning performance and their existing receptive vocabulary ability.     

Associations Between Syntax and the Lexicon Among Children With or Without ASD and Language Impairment

Five groups of children defined by presence or absence of syntactic deficits and autism spectrum disorders (ASD) took vocabulary tests and provided sentences, definitions, and word associations. Children with ASD who were free of syntactic deficits demonstrated age-appropriate word knowledge. Children with ASD plus concomitant syntactic language impairments (ASDLI) performed similarly to peers with specific language impairment (SLI) and both demonstrated sparse lexicons characterized by partial word knowledge and immature knowledge of word-to-word relationships. This behavioral overlap speaks to the robustness of the syntax–lexicon interface and points to a similarity in the ASDLI and SLI phenotypes.     

Serial order short-term memory capacities and specific language impairment: No evidence for a causal association

This study re-explored the nature of verbal short-term memory (STM) deficits in children with specific language impairment (SLI), by distinguishing item and serial order STM processes. Recent studies have shown serial order STM capacity to be a critical determinant of language development, relative to item STM. In Experiment 1, 12 children with SLI, 12 age-matched children and 12 language-matched children were administered serial order recognition and reconstruction tasks. Experiment 2 assessed implicit serial learning abilities via a Hebb learning task. The SLI group showed impaired performance for the serial order reconstruction and recognition tasks, relative to language-matched and/or age-matched control groups. However, normal serial position effects were observed in all SLI children in the serial order reconstruction task, suggesting normal coding of serial position information. Similarly, performance on the Hebb serial learning task was at chronological age appropriate levels. Experiment 3 showed that the group differences observed for the serial order STM tasks in Experiment 1 disappeared when the SLI group was compared to a mental age-matched control group. Experiment 4 showed similar performance levels in the SLI group and the mental age-matched control group for a nonword recognition task assessing item STM capacities. This study shows that children with SLI have no specific impairments for serial order and item STM components but that poorer general cognitive efficiency is related to functional limitations in verbal STM tasks. The data are in line with limited information processing accounts of SLI.     

Written language as a window into residual language deficits: a study of children with persistent and residual speech and language impairments

Previous work has suggested that, because writing is a late-acquired and complex skill, it may be a particularly sensitive index of language difficulties in children. Evidence in support of this view was obtained in a study contrasting 161 normally-developing control children aged from 7.5 to 13 years with 75 twin children of the same age who either had specific speech-language impairments, or were co-twins of affected children. Written narratives were elicited from children using a sequence of five photographs depicting a simple story, and were analysed for grammatical complexity and accuracy, intelligibility, and semantic content. Only 42 of the twins could spell well enough to attempt the narrative task. Some co-twins of affected children had deficits in written language, despite normal performance on oral language tests. Most children with language impairments were poor at writing, with particularly marked deficits on a measure of spelling and punctuation. Children with language impairments made a relatively high proportion of phonologically inaccurate spelling errors when compared with younger children at a similar vocabulary level. Those who did poorly on a nonword repetition test were especially likely to have poor written language. However, four children with pure speech difficulties produced age-appropriate written narratives.     

Benefits of augmentative signs in word learning: Evidence from children who are deaf/hard of hearing and children with specific language impairment

BackgroundAugmentative signs may facilitate word learning in children with vocabulary difficulties, for example, children who are Deaf/Hard of Hearing (DHH) and children with Specific Language Impairment (SLI). Despite the fact that augmentative signs may aid second language learning in populations with a typical language development, empirical evidence in favor of this claim is lacking.AimsWe aim to investigate whether augmentative signs facilitate word learning for DHH children, children with SLI, and typically developing (TD) children.Methods and proceduresWhereas previous studies taught children new labels for familiar objects, the present study taught new labels for new objects. In our word learning experiment children were presented with pictures of imaginary creatures and pseudo words. Half of the words were accompanied by an augmentative pseudo sign. The children were tested for their receptive word knowledge.Outcomes and resultsThe DHH children benefitted significantly from augmentative signs, but the children with SLI and TD age-matched peers did not score significantly different on words from either the sign or no-sign condition.Conclusions and implicationsThese results suggest that using Sign-Supported speech in classrooms of bimodal bilingual DHH children may support their spoken language development. The difference between earlier research findings and the present results may be caused by a difference in methodology.