Chiara Cantiani

Event-related potentials reveal anomalous morphosyntactic processing in developmental dyslexia

In the light of the literature describing oral language difficulties in developmental dyslexia (DD), event-related potentials were used in order to compare morphosyntactic processing in 16 adults with DD (aged 20–28 years) and unimpaired controls. Sentences including subject–verb agreement violations were presented auditorily, with grammaticality and subject number as main factors. Electrophysiological data revealed differences between groups concerning both the latency of the P600 component and the additional presence in the DD group of a negativity broadly diffused all over the scalp. Moreover, these electrophysiological anomalies increased when plural sentences were processed. On the whole, the results support the hypothesis of a linguistic deficit and of different language processing modalities in DD participants.

Sensitivity to lexical stress in dyslexia: A case of cognitive not perceptual stress

Sensitivity to lexical stress in adult German-speaking students with reading difficulty was investigated using minimal pair prepositional verbs whose meaning and syntax depend on the location of the stressed syllable. Two tests of stress perception were used: (i) a stress location task, where listeners indicated the location of the perceptually most prominent syllable, and (ii) a stress pattern identification task, where listeners indicated if the stress pattern was appropriate for its semantic frame. The students with reading difficulties performed worse than the normally reading students on both tasks. Their poorer performance did not reflect the lack of a percept for lexical stress rather patterns of performance across the two tasks suggested that each loaded onto different underlying cognitive abilities. Deficits in these, rather than perceptual difficulties, explained observed group differences. Students with reading difficulties have a normal implicit knowledge of lexical stress usage but lack the necessary cognitive resources for developing an explicit metalinguistic awareness of it. Deficits in these skills not deficiencies in lexical stress perception are implicated in their reading difficulties.

Auditory discrimination predicts linguistic outcome in Italian infants with and without familial risk for language learning impairment.

Highlights • Italian infants with familial risk for LLI show deficits in RAP abilities.• Early multi-feature RAP skills predict to later expressive language skills.• Different acoustical features are critical to normative language acquisition.• Early RAP skills represent a stable cross-linguistic risk marker for LLI.• Early intervention programs should be implemented based on these results.

Characterizing the morphosyntactic processing deficit and its relationship to phonology in developmental dyslexia

This study explores the morphosyntactic processing deficit in developmental dyslexia, addressing the on-going debate on the linguistic nature of the disorder, and directly testing the hypothesis that the deficit is based on underlying processing difficulties, such as acoustic and/or phonological impairments. Short German sentences consisting of a pronoun and a verb, either correct or containing a morphosyntactic violation, were auditorily presented to 17 German-speaking adults with dyslexia, and 17 matched control participants, while an EEG was recorded. In order to investigate the interaction between low-level phonological processing and morphosyntactic processing, the verbal inflections were manipulated to consist of different levels of acoustic salience. The event-related potential (ERP) results confirm altered morphosyntactic processing in participants with dyslexia, especially when morphosyntactic violations are expressed by both lexical and inflectional changes. Moreover, ERP data on phoneme discrimination and behavioural data on phonemic awareness and verbal short-term memory reveal phonological deficits in dyslexic participants. However, a causal relationship between phonological and morphosyntactic processing was not conclusive, because anomalous morphosyntactic processing in dyslexia is not directly mediated by acoustic salience, rather it correlates with high-level phonological skills and is mediated by lexical cues.

Perception of Non-Verbal Auditory Stimuli in Italian Dyslexic Children

Auditory temporal processing deficits have been proposed as the underlying cause of phonological difficulties in Developmental Dyslexia. The hypothesis was tested in a sample of 20 Italian dyslexic children aged 8–14, and 20 matched control children. Three tasks of auditory processing of non-verbal stimuli, involving discrimination and reproduction of sequences of rapidly presented short sounds were expressly created. Dyslexic subjects performed more poorly than control children, suggesting the presence of a deficit only partially influenced by the duration of the stimuli and of inter-stimulus intervals (ISIs).

Age, dyslexia subtype and comorbidity modulate rapid auditory processing in developmental dyslexia

The nature of Rapid Auditory Processing (RAP) deficits in dyslexia remains debated, together with the specificity of the problem to certain types of stimuli and/or restricted subgroups of individuals. Following the hypothesis that the heterogeneity of the dyslexic population may have led to contrasting results, the aim of the study was to define the effect of age, dyslexia subtype and comorbidity on the discrimination and reproduction of non-verbal tone sequences. Participants were 46 children aged 8–14 (26 with dyslexia, subdivided according to age, presence of a previous language delay, and type of dyslexia). Experimental tasks were a Temporal Order Judgment (TOJ) (manipulating tone length, ISI and sequence length), and a Pattern Discrimination Task. Dyslexic children showed general RAP deficits. Tone length and ISI influenced dyslexic and control childrens performance in a similar way, but dyslexic children were more affected by an increase from 2 to 5 sounds. As to age, older dyslexic childrens difficulty in reproducing sequences of 4 and 5 tones was similar to that of normally reading younger (but not older) children. In the analysis of subgroup profiles, the crucial variable appears to be the advantage, or lack thereof, in processing long vs. short sounds. Dyslexic children with a previous language delay obtained the lowest scores in RAP measures, but they performed worse with shorter stimuli, similar to control children, while dyslexic-only children showed no advantage for longer stimuli. As to dyslexia subtype, only surface dyslexics improved their performance with longer stimuli, while phonological dyslexics did not. Differential scores for short vs. long tones and for long vs. short ISIs predict non-word and word reading, respectively, and the former correlate with phonemic awareness. In conclusion, the relationship between non-verbal RAP, phonemic skills and reading abilities appears to be characterized by complex interactions with subgroup characteristics.

Developmental Dyslexia With and Without Language Impairment: ERPs Reveal Qualitative Differences in Morphosyntactic Processing

This study aimed to characterize neuropsychological and linguistic skills in children with Developmental Dyslexia (DD) with and without Language Impairment (LI). Behavioral tests of short-term memory, phonemic awareness, and morphosyntactic processing and electrophysiological responses to agreement violations were administered to 32 DD children (16 with additional LI) and 16 controls. Behavioral data revealed quantitative differences among groups: DD+LI children showed the worst performance, followed by DD-only children and controls. Event-related potential results confirmed atypical morphosyntactic processing in the DD-only group, highlighting qualitative differences between groups. These results support multifactor models of learning disabilities, where different patterns of deficits characterize different subgroups.

From Sensory Perception to Lexical-Semantic Processing: An ERP Study in Non-Verbal Children with Autism.

This study examines electrocortical activity associated with visual and auditory sensory perception and lexical-semantic processing in nonverbal (NV) or minimally-verbal (MV) children with Autism Spectrum Disorder (ASD). Currently, there is no agreement on whether these children comprehend incoming linguistic information and whether their perception is comparable to that of typically developing children. Event-related potentials (ERPs) of 10 NV/MV children with ASD and 10 neurotypical children were recorded during a picture-word matching paradigm. Atypical ERP responses were evident at all levels of processing in children with ASD. Basic perceptual processing was delayed in both visual and auditory domains but overall was similar in amplitude to typically-developing children. However, significant differences between groups were found at the lexical-semantic level, suggesting more atypical higher-order processes. The results suggest that although basic perception is relatively preserved in NV/MV children with ASD, higher levels of processing, including lexical- semantic functions, are impaired. The use of passive ERP paradigms that do not require active participant response shows significant potential for assessment of non-compliant populations such as NV/MV children with ASD.

From CNTNAP2 to early expressive language in infancy : the mediation role of rapid auditory processing

Although it is clear that early language acquisition can be a target of CNTNAP2, the pathway between gene and language is still largely unknown. This research focused on the mediation role of rapid auditory processing (RAP). We tested RAP at 6 months of age by the use of event-related potentials, as a mediator between common variants of the CNTNAP2 gene (rs7794745 and rs2710102) and 20-month-old language outcome in a prospective longitudinal study of 96 Italian infants. The mediation model examines the hypothesis that language outcome is explained by a sequence of effects involving RAP and CNTNAP2. The ability to discriminate spectrotemporally complex auditory frequency changes at 6 months of age mediates the contribution of rs2710102 to expressive vocabulary at 20 months. The indirect effect revealed that rs2710102 C/C was associated with lower P3 amplitude in the right hemisphere, which, in turn, predicted poorer expressive vocabulary at 20 months of age. These findings add to a growing body of literature implicating RAP as a viable marker in genetic studies of language development. The results demonstrate a potential developmental cascade of effects, whereby CNTNAP2 drives RAP functioning that, in turn, contributes to early expressive outcome.

Working memory mediates the effects of gestational age at birth on expressive language development in children

Objective: This study tested the role of temporary memory, measured by phonological short-term memory (pSTM) and verbal working memory (vWM), as a mediator of the effect of 3 putative risk factors (i.e., socioeconomic status, home literacy environment, birth gestational age) upon expressive and receptive language. Method: A community-based sample of 646 Italian children aged 6–11 years was assessed with a comprehensive battery of language and cognitive tests. A mediation analysis was used to examine whether memory mediates environmental/biological effects on language. Results: The results demonstrated a developmental cascade of effects, whereby the duration of pregnancy drives vWM functioning that, in turn, may affect expressive linguistic outcome Conclusion: Treatments focused on vWM, specifically to preterm children, may improve their language development, with enduring consequences on educational and psychosocial outcomes.