Speech-specific perceptual adaptation deficits in children and adults with dyslexia

According to several influential theoretical frameworks, phonological deficits in dyslexia result from reduced sensitivity to acoustic cues that are essential for the development of robust phonemic representations. Some accounts suggest that these deficits arise from impairments in rapid auditory adaptation processes that are either speech-specific or domain-general. Here, we examined the specificity of auditory adaptation deficits in dyslexia using a non-linguistic tone anchoring (adaptation) task and a linguistic selective adaptation task in children and adults with and without dyslexia. Children and adults with dyslexia had elevated tone-frequency discrimination thresholds, but both groups benefitted from anchoring to repeated stimuli to the same extent as typical readers. Additionally, although both dyslexia groups had overall reduced accuracy for speech sound identification, only the child group had reduced categorical perception for speech. Across both age groups, individuals with dyslexia had reduced perceptual adaptation to speech. These results highlight broad auditory perceptual deficits across development in individuals with dyslexia for both linguistic and non-linguistic domains, but speech-specific adaptation deficits. Finally, mediation models in children and adults revealed that the causal pathways from basic perception and adaptation to phonological awareness through speech categorization were not significant. Thus, rather than having causal effects, perceptual deficits may co-occur with the phonological deficits in dyslexia across development.

Phonological Deficits in Turkish Dyslexic Students

Dyslexia is a spesific learning disability that is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. Due to these difficulties, phonological component of language is also affected. Via an articulation test, it was revealed that dyslexic students made errors in some consonants both at the beginning and at the end of the words. There was a relation between the age and dyslexia on the performance of phonological tasks whereas this relation could not be found between gender and dyslexia. As proposed before, the students without dyslexia made less errors compared to the dyslexic students.

Speech–Brain Frequency Entrainment of Dyslexia with and without Phonological Deficits

Developmental dyslexia is a cognitive disorder characterized by difficulties in linguistic processing. Our purpose is to distinguish subtypes of developmental dyslexia by the level of speech–EEG frequency entrainment (δ: 1–4; β: 12.5–22.5; γ1: 25–35; and γ2: 35–80 Hz) in word/pseudoword auditory discrimination. Depending on the type of disabilities, dyslexics can divide into two subtypes—with less pronounced phonological deficits (NoPhoDys—visual dyslexia) and with more pronounced ones (PhoDys—phonological dyslexia). For correctly recognized stimuli, the δ-entrainment is significantly worse in dyslexic children compared to controls at a level of speech prosody and syllabic analysis. Controls and NoPhoDys show a stronger δ-entrainment in the left-hemispheric auditory cortex (AC), anterior temporal lobe (ATL), frontal, and motor cortices than PhoDys. Dyslexic subgroups concerning normolexics have a deficit of δ-entrainment in the left ATL, inferior frontal gyrus (IFG), and the right AC. PhoDys has higher δ-entrainment in the posterior part of adjacent STS regions than NoPhoDys. Insufficient low-frequency β changes over the IFG, the inferior parietal lobe of PhoDys compared to NoPhoDys correspond to their worse phonological short-term memory. Left-dominant 30 Hz-entrainment for normolexics to phonemic frequencies characterizes the right AC, adjacent regions to superior temporal sulcus of dyslexics. The pronounced 40 Hz-entrainment in PhoDys than the other groups suggest a hearing “reassembly” and a poor phonological working memory. Shifting up to higher-frequency γ-entrainment in the AC of NoPhoDys can lead to verbal memory deficits. Different patterns of cortical reorganization based on the left or right hemisphere lead to differential dyslexic profiles.

The Speech “Bamana”: Using the Syllable Repetition Task to Identify Underlying Phonological Deficits in Children With Speech and Language Impairments

Purpose This study compared performance on the Syllable Repetition Task (SRT) by preschoolers with diverse speech and language abilities to identify underlying impairments in speech processes. Method Three groups of 13 children ages 4 and 5 years with (a) typically developing (TD) speech and language, (b) speech sound disorder (SSD), and (c) comorbid developmental language disorder and speech sound disorder (DLD + SSD) completed the SRT. We calculated competence, memory, encoding, and transcoding scores, as well as word-initial stress pattern and vowel accuracy. Results A 3 × 3 (Group × Syllable length) factorial multivariate analysis of covariance revealed group differences for all measures and syllable length differences for memory, transcoding, and competence. There were no interactions between group and syllable length. TD children obtained the highest scores on each measure, though children with DLD + SSD performed similarly to TD children on encoding when vocabulary was included as a covariate. Children with SSD only outperformed children with DLD + SSD on competence and transcoding, and these two groups performed similarly on memory. A separate exploratory analysis using a 3 × 3 multivariate analysis of covariance revealed that children with DLD + SSD were more likely than children in the other groups to produce weak word-initial stress and vowel errors during syllable repetition. Conclusion Children with SSD and DLD + SSD exhibit underlying phonological deficits on the SRT compared to TD children. Results support the claim that memory and encoding are deficits in SSD. In addition, transcoding deficits were identified among children with no known oromotor impairment. Therefore, more research is required to identify the relationship between SRT performance and explicit measures of phonological processing.

Aberrant Prestimulus Oscillations in Developmental Dyslexia Support an Underlying Attention Shifting Deficit

Developmental dyslexia (DD) impairs reading and writing acquisition in 5–10% of children, compromising schooling, academic success, and everyday adult life. DD associates with reduced phonological skills, evident from a reduced auditory mismatch negativity (MMN) in the electroencephalogram (EEG). It was argued that such phonological deficits are secondary to an underlying deficit in the shifting of attention to upcoming speech sounds. Here, we tested whether the aberrant MMN in individuals with DD is a function of EEG correlates of prestimulus attention shifting; based on prior findings, we focused prestimulus analyses on alpha-band oscillations. We administered an audio–visual oddball paradigm to school children with and without DD. Children with DD showed EEG markers of deficient attention switching (i.e., increased prestimulus alpha-band intertrial phase coherence [ITPC]) to precede and predict their reduced MMN—aberrantly increased ITPC predicted an aberrantly reduced MMN. In interaction, ITPC and MMN predicted reading abilities, such that poor readers showed both high ITPC and a reduced MMN, the reverse being true in good readers. Prestimulus ITPC may be an overlooked biomarker of deficient attention shifting in DD. The findings support the proposal that an attention shifting deficit underlies phonological deficits in DD, entailing new opportunities for targeted intervention.

Neurocognitive Bases of Crossmodal Integration Deficit in Dyslexia

Crossmodal integration is a critical component of successful reading, and yet it has been less studied than reading’s unimodal subskills. Proficiency with the sounds of a language (i.e., the phonemes) and with the visual representations of these sounds (graphemes) are both important and necessary precursors for reading, but the formation of a stable integrated representation that combines and links these aspects, and subsequent fluent and automatic access to this crossmodal representation, is unique to reading and is required for its success. Indeed, individuals with specific difficulties in reading, as in dyslexia, demonstrate impairments not only in phonology and orthography but also in integration. Impairments in only crossmodal integration could result in disordered reading via disrupted formation of or access to phoneme–grapheme associations. Alternately, the phonological deficits noted in many individuals with dyslexia may lead to reading difficulties via issues with integration: children who cannot consistently identify and manipulate the sounds of their language will also have trouble matching these sounds to their visual representations, resulting in the manifested deficiencies. We here discuss the importance of crossmodal integration in reading, both generally and as a potential specific causal deficit in the case of dyslexia. We examine the behavioral, functional, and structural neural evidence for a crossmodal, as compared to unimodal, processing issue in individuals with dyslexia in comparison to typically developing controls. We then present an initial review of work using crossmodal- versus unimodal-based reading interventions and training programs aimed at the amelioration of reading difficulties. Finally, we present some remaining questions reflecting potential areas for future research into this topic.

Dyslexia versus visual difficulties in reading and writing. A comment in discussion

Due to the fact that it is frequently difficult to identify their etiological origins, reading and writing difficulties have inconsistent terminology in the literature. This article is a review and attempts to initiate a discussion about visual dyslexia. The authors pose the question whether - in the context of new neuroimaging methods and the neurosciences broadly defined - there exist reading and writing difficulties that stem from impaired functioning of the visual system and whether they can be assigned to developmental dyslexia. If it is assumed that developmental dyslexia is linguistic in nature, these are phonological deficits that come to the fore in children entering the world of reading. These phonological processing deficits impair word decoding (word identification), making word recognition impossible, thus preventing access to higher-order linguistic processes, that is comprehending meaning from texts or building one’s own narratives.

role of socialisation in the development of phonological, syntactical and lexical aspects of language

Rapid linguistic development is believed to occur in early childhood because of the malleability of this period (Hutterlocher, et al., 1991; Maccoby, 1992). The aim of this paper is to evaluate the role of socialisation as a contributor to first-language acquisition in terms of the phonological, lexical and syntactical aspects of language. The relative importance of nativist-and usage-based approaches to language is examined. Following from that, the role of the amount, type and period of exposure to speech in the process of learning English as a first-language. This paper explores a number of studies of typical and atypical children in the relevant literature. It concludes that language acquisition is driven both by innate ability and by environmental factors, i.e. society, or social elements are significant as activators of the human being’s innate ability to acquire language. According to this paper, the deprivation of socialisation is critical to many aspects of language development, most importantly syntactic, and least importantly phonological. Deficits in phonological aspects are only seen in the case of atypical children, and the cases of autistic children, while lexical development can be seen in both cases; typical and atypical. The results of the studies investigated in this paper suggest that syntax is aspect of language most affected by inadequate exposure to language. It also concluded that these three aspects of language acquisition are also likely to be influenced by a critical period, which is a proposal of nativism.