Developmental Language Disorder as Syntactic Prediction Impairment.

We provide evidence that children with Developmental Language Disorder (DLD) are impaired in predictive syntactic processing. In the current study, children listened passively to auditorily-presented sentences, where the critical condition included an unexpected "filled gap" in the direct object position of the relative clause verb. A filled gap is illustrated by the underlined phrase in "The zebra that the hippo kissed the camel on the nose…", rather than the expected "the zebra that the hippo kissed [e] on the nose", where [e] denotes the gap. Brain responses to the filled gap were compared to a control condition using adverb-relative clauses with identical substrings: "The weekend that the hippo kissed the camel on the nose [e]…". Here, the same noun phrase is not unexpected because the adverb gap occurs later in the structure. We hypothesized that a filled gap would elicit a prediction error brain signal in the form of an early anterior negativity, as we have previously observed in adults. We found an early (bilateral) anterior negativity to the filled gap in a control group of children with Typical Development (TD), but the children with DLD exhibited no brain response to the filled gap during the same early time window. This suggests that children with DLD fail to predict that a relativized object should correspond to an empty position after the relative clause verb, suggesting an impairment in predictive processing. We discuss how this lack of a prediction error signal can interact with language acquisition and result in DLD.

Electrophysiological indices of brain activity to content and function words in discourse.

BACKGROUND: An increase in positivity of event-related potentials (ERPs) at the lateral anterior sites has been hypothesized to be an index of semantic and discourse processing, with the right lateral anterior positivity (LAP) showing particular sensitivity to discourse factors. However, the research investigating the LAP is limited; it is unclear whether the effect is driven by word class (function word versus content word) or by a more general process of structure building triggered by elements of a determiner phrase (DP). AIMS: To examine the neurophysiological indices of semantic/discourse integration using two different word categories (function versus content word) in the discourse contexts and to contrast processing of these word categories in meaningful versus nonsense contexts. METHODS & PROCEDURES: Planned comparisons of ERPs time locked to a function word stimulus 'the' and a content word stimulus 'cats' in sentence-initial position were conducted in both discourse and nonsense contexts to examine the time course of processing following these word forms. OUTCOMES & RESULTS: A repeated-measures analysis of variance (ANOVA) for the Discourse context revealed a significant interaction of condition and site due to greater positivity for 'the' relative to 'cats' at anterior and superior sites. In the Nonsense context, there was a significant interaction of condition, time and site due to greater positivity for 'the' relative to 'cats' at anterior sites from 150 to 350 ms post-stimulus offset and at superior sites from 150 to 200 ms post-stimulus offset. Overall, greater positivity for both 'the' and 'cats' was observed in the discourse relative to the nonsense context beginning approximately 150 ms post-stimulus offset. Additionally, topographical analyses were highly correlated for the two word categories when processing meaningful discourse. This topographical pattern could be characterized as a prominent right LAP. The LAP was attenuated when the target stimulus word initiated a nonsense context. CONCLUSIONS & IMPLICATIONS: The results of this study support the view that the right LAP is an index of general discourse processing rather than an index of word class. These findings demonstrate that the LAP can be used to study discourse processing in populations with compromised metalinguistic skills, such as adults with aphasia or traumatic brain injury.

Five heads are better than one: preliminary results of team-based learning in a communication disorders graduate course.

BACKGROUND: Clinical problem-solving is fundamental to the role of the speech-language pathologist in both the diagnostic and treatment processes. The problem-solving often involves collaboration with clients and their families, supervisors, and other professionals. Considering the importance of cooperative problem-solving in the profession, graduate education in speech-language pathology should provide experiences to foster the development of these skills. One evidence-based pedagogical approach that directly targets these abilities is team-based learning (TBL). TBL is a small-group instructional method that focuses on students' in-class application of conceptual knowledge in solving complex problems that they will likely encounter in their future clinical careers. AIMS: The purpose of this pilot study was to investigate the educational outcomes and students' perceptions of TBL in a communication disorders graduate course on speech and language-based learning disabilities. METHODS & PROCEDURES: Nineteen graduate students (mean age = 26 years, SD = 4.93), divided into three groups of five students and one group of four students, who were enrolled in a required graduate course, participated by fulfilling the key components of TBL: individual student preparation; individual and team readiness assurance tests (iRATs and tRATs) that assessed preparedness to apply course content; and application activities that challenged teams to solve complex and authentic clinical problems using course material. OUTCOMES & RESULTS: Performance on the tRATs was significantly higher than the individual students' scores on the iRATs (p < .001, Cohen's d = 4.08). Students generally reported favourable perceptions of TBL on an end-of-semester questionnaire. Qualitative analysis of responses to open-ended questions organized thematically indicated students' high satisfaction with application activities, discontent with the RATs, and recommendations for increased lecture in the TBL process. CONCLUSIONS & IMPLICATIONS: The outcomes of this pilot study suggest the effectiveness of TBL as an instructional method that provides student teams with opportunities to apply course content in problem-solving activities followed by immediate feedback. This research also addresses the dearth of empirical information on how graduate programmes in speech-language pathology bridge students' didactic learning and clinical practice. Future studies should examine the utility of this approach in other courses within the field and with more heterogeneous student populations.

An electrophysiological investigation of discourse coherence in healthy adults.

This study used event-related potentials (ERPs) to investigate discourse-coherence processing. Because there are scant data on ERP indices of discourse coherence in typical adults, it is important to study a non-clinical population before examining clinical populations. Twelve adults listened to a story with sentences in a coherent versus incoherent order. Sequences of nonsense syllables served as a control. ERPs in the 200-400 ms time window, reflecting phonological and lexical processing, and in the 600-900 ms time window, reflecting later discourse processing for integration, were investigated. Results revealed a right anterior and posterior positivity that was greater for coherent than for incoherent discourse during the 600-900 ms time window. These findings point to an index of discourse coherence and further suggest that ERPs can be used as a clinical tool to study discourse-processing disorders in populations with brain damage, such as aphasia and traumatic brain injury.

Can children with SLI detect cognitive conflict? Behavioral and electrophysiological evidence.

PURPOSE: This study examined whether children with specific language impairment (SLI) are deficient in detecting cognitive conflict between competing response tendencies in a GO/No-GO task. METHOD: Twelve children with SLI (ages 10-12), 22 children with typical language development matched group-wise on age (TLD-A), and 16 younger children with TLD (ages 8-9) matched group-wise on language skills (TLD-L) were tested using a behavioral GO/No-GO paradigm with simultaneous collection of event-related potentials. The N2 component was used as a neural index of the ability to detect conflict between GO and No-GO response tendencies. RESULTS: Hit rates did not differentiate the 3 groups. The TLD-L children demonstrated the highest false-alarm rates. The N2 component was attenuated and showed delayed divergence of GO and No-GO amplitudes in SLI relative to TLD-A children in response to stimuli presented at various probability levels. The N2 effect in children with SLI resembled that of children with TLD who were approximately 3 years younger. CONCLUSIONS: School-age children with SLI exhibit a maturational lag in detecting conflict between competing response alternatives. Deficient conflict detection may in turn hinder these children's ability to resolve conflict among semantic representations that are activated during language processing.

ERPs reveal atypical processing of subject versus object Wh-questions in children with specific language impairment.

BACKGROUND: Children with specific language impairment (SLI) show particular difficulty comprehending and producing object (Who did the bear follow?) relative to subject (Who followed the tiger?) wh-questions. AIMS: To determine if school-age children with SLI, relative to children with typical development (TD), show a more distinct unevenness, or asymmetry, in the comprehension of these questions. In addition, this study examined whether the sustained left-anterior negativity (LAN) in event-related potentials (ERP) could be used as a marker for atypical processing of these questions in children with SLI. The LAN effect signals the greater working memory processes for maintaining in memory the dislocated object in object wh-questions and reflects working memory capacity in adults. It was predicted that the amplitude of the LAN would be greater in children with SLI, reflecting the characteristic low working memory capacity in this population. The concomitance of these behavioural and electrophysiological effects would suggest that the subject-object asymmetry in SLI should be investigated in relation to poor working memory skills. METHODS & PROCEDURES: Groups including 13 children with SLI, 17 same-age TD children and 18 normal adults completed an auditory sentence comprehension task requiring button responses while continuous electroencephalography (EEG) was collected. Accuracy for subject and object questions was calculated. The mean amplitude values of the ERP data for the wh-questions were examined to identify differential processing of subject and object questions. OUTCOMES & RESULTS: TD children demonstrated asymmetrical comprehension of subject and object wh-questions, whereas children with SLI comprehended both question types poorly and adults did not show subject-object asymmetry. ERP waveforms spanning the wh-dependency revealed a large and widespread sustained anterior positivity for object relative to subject questions in the TD group, indicating differential processing of these questions. This effect was attenuated and non-significant in the SLI group. The adults' grand average waveforms showed the expected LAN effect, which was opposite in polarity relative to the children, although it only approached significance. CONCLUSIONS & IMPLICATIONS: The finding of less differential processing of subject and object wh-questions in SLI relative to TD children suggests inefficient maintenance of sentential information in working memory for object questions in SLI. Whereas behavioural methods did not identify subject-object asymmetry in SLI, the more fine-grained method of ERPs elucidated this effect. Further analysis of working memory as the basis for the subject-object asymmetry in SLI is critical for identifying appropriate intervention targets for this population.

Syntactic structural assignment in Brazilian Portuguese-speaking children with specific language impairment.

PURPOSE: In this study, the authors examined the comprehension of sentences with predicates and reflexives that are linked to a nonadjacent noun as a test of the hierarchical ordering deficit (HOD) hypothesis. That hypothesis and more modern versions posit that children with specific language impairment (SLI) have difficulty in establishing nonadjacent (hierarchical) relations among elements of a sentence. The authors also tested whether additional working memory demands in constructions containing reflexives affected the extent to which children with SLI incorrectly structure sentences as indicated by their picture-pointing comprehension responses. METHOD: Sixteen Brazilian Portuguese-speaking children (8;4-10;6 [years;months]) with SLI and 16 children with typical language development (TLD) matched for age (± 3 months), gender, and socioeconomic status participated in 2 experiments (predicate and reflexive interpretation). In the reflexive experiment, the authors also manipulated working memory demands. Each experiment involved a 4-choice picture selection sentence comprehension task. RESULTS: Children with SLI were significantly less accurate on all conditions. Both groups made more hierarchical syntactic construction errors in the long working memory condition than in the short working memory condition. CONCLUSION: The HOD hypothesis was not confirmed. For both groups, syntactic factors (structural assignment) were more vulnerable than lexical factors (prepositions) to working memory effects in sentence miscomprehension.