Phonological representations, reading development and dyslexia: towards a cross-linguistic theoretical framework

Orthography-phonology consistency in English: Theory- and data-driven measures and their impact on auditory vs. visual word recognition

Research on orthographic consistency in English words has selectively identified different sub-syllabic units in isolation (grapheme, onset, vowel, coda, rime), yet there is no comprehensive assessment of how these measures affect word identification when taken together. To study which aspects of consistency are more psychologically relevant, we investigated their independent and composite effects on human reading behavior using large-scale databases. Study 1 found effects on adults' naming responses of both feedforward consistency (orthography to phonology) and feedback consistency (phonology to orthography). Study 2 found feedback but no feedforward consistency effects on visual and auditory lexical decision tasks, with the best predictor being a composite measure of consistency across grapheme, rime, OVC, and word-initial letter-phoneme. In Study 3, we explicitly modeled the reading process with forward and backward flow in a bidirectionally connected neural network. The model captured latent dimensions of quasi-regular mapping that explain additional variance in human reading and spelling behavior, compared to the established measures. Together, the results suggest interactive activation between phonological and orthographic word representations. They also validate the role of computational analyses of language to better understand how print maps to sound, and what properties of natural language affect reading complexity.

Event Related Potentials to Native Speech Contrasts Predicts Word Reading Abilities in Early School-Aged Children

Speech perception skills have been implicated in the development of phoneme-grapheme correspondence, yet the exact nature of speech perception and word reading ability remains unknown. We investigate phonological sensitivity to native (English) and nonnative (Spanish) speech syllables within an auditory oddball paradigm using event related potentials (ERPs) collected from lateral temporal electrode sites in 33 monolingual English-speaking children aged 6-8 years (N=33). We further explore the relationship between ERPs to English word reading abilities for this group. Results revealed that language stimuli (English, Spanish), ERP condition (standard, deviant), and hemisphere (left, right) all influenced the lateral N1 component. ERPs recorded from deviant English stimuli were significantly more negative within the left hemisphere compared to all other recorded ERPs. Mean amplitude differences within the N1 in left lateral electrode sites recorded in response to English phoneme contrasts significantly predicted English word reading abilities within this sample. Results indicate that speech perception of native contrasts recorded in left temporal electrode sites for the N1 component are linked to English word reading abilities in early school-aged children.

Attentional modulation of neural sound tracking in children with and without dyslexia

Auditory selective attention forms an important foundation of children's learning by enabling the prioritisation and encoding of relevant stimuli. It may also influence reading development, which relies on metalinguistic skills including the awareness of the sound structure of spoken language. Reports of attentional impairments and speech perception difficulties in noisy environments in dyslexic readers are also suggestive of the putative contribution of auditory attention to reading development. To date, it is unclear whether non-speech selective attention and its underlying neural mechanisms are impaired in children with dyslexia and to which extent these deficits relate to individual reading and speech perception abilities in suboptimal listening conditions. In this EEG study, we assessed non-speech sustained auditory selective attention in 106 7-to-12-year-old children with and without dyslexia. Children attended to one of two tone streams, detecting occasional sequence repeats in the attended stream, and performed a speech-in-speech perception task. Results show that when children directed their attention to one stream, inter-trial-phase-coherence at the attended rate increased in fronto-central sites; this, in turn, was associated with better target detection. Behavioural and neural indices of attention did not systematically differ as a function of dyslexia diagnosis. However, behavioural indices of attention did explain individual differences in reading fluency and speech-in-speech perception abilities: both these skills were impaired in dyslexic readers. Taken together, our results show that children with dyslexia do not show group-level auditory attention deficits but these deficits may represent a risk for developing reading impairments and problems with speech perception in complex acoustic environments. RESEARCH HIGHLIGHTS: Non-speech sustained auditory selective attention modulates EEG phase coherence in children with/without dyslexia Children with dyslexia show difficulties in speech-in-speech perception Attention relates to dyslexic readers' speech-in-speech perception and reading skills Dyslexia diagnosis is not linked to behavioural/EEG indices of auditory attention.

Phoneme Representation and Articulatory Impairment: Insights from Adults with Comorbid Motor Coordination Disorder and Dyslexia

Phonemic processing skills are impaired both in children and adults with dyslexia. Since phoneme representation development is based on articulatory gestures, it is likely that these gestures influence oral reading-related skills as assessed through phonemic awareness tasks. In our study, fifty-two young dyslexic adults, with and without motor impairment, and fifty-nine skilled readers performed reading, phonemic awareness, and articulatory tasks. The two dyslexic groups exhibited slower articulatory rates than skilled readers and the comorbid dyslexic group presenting with an additional difficulty in respiratory control (reduced speech proportion and increased pause duration). Two versions of the phoneme awareness task (PAT) with pseudoword strings were administered: a classical version under time pressure and a delayed version in which access to phonemic representations and articulatory programs was facilitated. The two groups with dyslexia were outperformed by the control group in both versions. Although the two groups with dyslexia performed equally well on the classical PAT, the comorbid group performed significantly less efficiently on the delayed PAT, suggesting an additional contribution of articulatory impairment in the task for this group. Overall, our results suggest that impaired phoneme representations in dyslexia may be explained, at least partially, by articulatory deficits affecting access to them.

Discriminatory Brain Processes of Native and Foreign Language in Children with and without Reading Difficulties

The association between impaired speech perception and reading difficulty has been well established in native language processing, as can be observed from brain activity. However, there has been scarce investigation of whether this association extends to brain activity during foreign language processing. The relationship between reading skills and neuronal speech representation of foreign language remains unclear. In the present study, we used event-related potentials (ERPs) with high-density EEG to investigate this question. Eleven- to 13-year-old children typically developed (CTR) or with reading difficulties (RD) were tested via a passive auditory oddball paradigm containing native (Finnish) and foreign (English) speech items. The change-detection-related ERP responses, the mismatch response (MMR), and the late discriminative negativity (LDN) were studied. The cluster-based permutation tests within and between groups were performed. The results showed an apparent language effect. In the CTR group, we found an atypical MMR in the foreign language processing and a larger LDN response for speech items containing a diphthong in both languages. In the RD group, we found unstable MMR with lower amplitude and a nonsignificant LDN response. A deficit in the LDN response in both languages was found within the RD group analysis. Moreover, we observed larger brain responses in the RD group and a hemispheric polarity reversal compared to the CTR group responses. Our results provide new evidence that language processing differed between the CTR and RD groups in early and late discriminatory responses and that language processing is linked to reading skills in both native and foreign language contexts.

Identifying the risk of dyslexia in bilingual children: The potential of language-dependent and language-independent tasks

This study investigates the linguistic processing and non-linguistic cognitive abilities of monolingual and bilingual children with and without reading difficulties and examines the relationship between these skills and reading. There were 72 Italian-speaking children: 18 monolingual good readers (MONO-GR, M_age = 10;4), 19 monolingual poor readers (MONO-PR, M_age = 10;3), 21 bilingual good readers (BI-GR, M_age = 10;6), and 16 bilingual poor readers (BI-PR, M_age = 10;6). All bilingual children spoke Italian as their L2. Children completed a battery of standardized Italian reading tests, language-dependent tasks: nonword repetition (NWR), sentence repetition (SR), and phonological awareness (PA), and language-independent tasks: timing anticipation, beat synchronization, inhibition control, auditory reaction time, and rapid automatized naming (RAN). Poor readers scored below good readers on the language-dependent tasks, including NWR, PA, and SR. Beat synchronization was the only language-independent task sensitive to reading ability, with poor readers showing greater variability than good readers in tapping to fast rhythms. SR was the only task influenced by language experience as bilinguals underperformed monolinguals on the task. Moreover, there were weak to moderate correlations between performance on some language-dependent tasks (NWR, PA), language-independent tasks (inhibition control, RAN), and reading measures. Performance on the experimental tasks (except for RAN) was not associated with the length of exposure to Italian. The results highlight the potential of NWR, PA, SR, and beat synchronization tasks in identifying the risk of dyslexia in bilingual populations. Future research is needed to validate these findings and to establish the tasks' diagnostic accuracy.

Brain Source Correlates of Speech Perception and Reading Processes in Children With and Without Reading Difficulties

Neural correlates in reading and speech processing have been addressed extensively in the literature. While reading skills and speech perception have been shown to be associated with each other, their relationship remains debatable. In this study, we investigated reading skills, speech perception, reading, and their correlates with brain source activity in auditory and visual modalities. We used high-density event-related potentials (ERPs), fixation-related potentials (FRPs), and the source reconstruction method. The analysis was conducted on 12–13-year-old schoolchildren who had different reading levels. Brain ERP source indices were computed from frequently repeated Finnish speech stimuli presented in an auditory oddball paradigm. Brain FRP source indices were also computed for words within sentences presented in a reading task. The results showed significant correlations between speech ERP sources and reading scores at the P100 (P1) time range in the left hemisphere and the N250 time range in both hemispheres, and a weaker correlation for visual word processing N170 FRP source(s) in the posterior occipital areas, in the vicinity of the visual word form areas (VWFA). Furthermore, significant brain-to-brain correlations were found between the two modalities, where the speech brain sources of the P1 and N250 responses correlated with the reading N170 response. The results suggest that speech processes are linked to reading fluency and that brain activations to speech are linked to visual brain processes of reading. These results indicate that a relationship between language and reading systems is present even after several years of exposure to print.

Speech perception in noise in children with dyslexia: Does speech sound disorder matter?

The aim of this observational cohort study with a control group is to compare consonant perception skills in quiet and in noise in children with typical language and learning development and in children with dyslexia, with and without Speech Sound Disorder (SSD). Three groups were included: A control group of twenty children with normal reading abilities and typical language development, twelve children with dyslexia and typical language development and thirteen children with dyslexia and SSD. All subjects received a consonant recognition test in three different listening conditions (quiet, + 10 and 0 Signal-to-Noise Ratio). In all test conditions, children with dyslexia and SSD had significantly lower consonant recognition scores than the control group and the children with dyslexia and typical language development (p < .0001). The poorer performances observed in children with dyslexia and SSD may be explained by impaired phonological processing underlying both conditions.

Early Productive Vocabulary Composition as Precursor of Dyslexia

PURPOSE

The aim of this study was to gain more insight into the linguistic characterization of dyslexia by investigating vocabulary acquisition. In a previous study, vocabulary at 17 months of age appeared to be related to familial risk (FR) of dyslexia. The aim of this study was to investigate how the differences in lexical composition further develop up to 3 years (35 months) of age and, more importantly, to what extent these differences can be considered specific precursors of dyslexia later on.

METHOD

In a total number of 262 children from the Dutch Dyslexia Program, 169 with and 93 without FR for dyslexia, productive vocabulary was assessed with the Dutch version of the MacArthur Communicative Development Inventories at ages 17, 23, 29, and 35 months. Reading tests were administered in Grades 2 and 3, resulting in dyslexia diagnosis in 60 FR children (FR-dys), leaving 109 FR children who developed normal reading skills (FR-nondys) and 93 control children. Children's expressive vocabulary was scored according to the total number of words produced and according to the different major linguistic word categories: nouns, predicates, and closed-class words. The analyses comprised a comparison of total productive vocabulary and the number of words per grammatical category at four different ages for the three groups (FR-dys, FR-nondys, and control). Also, correlations were calculated between vocabulary scores and reading scores.

RESULTS

Up to 29 months of age, the total numbers of nouns, predicates, and closed-class words are significantly lower for the FR-dys group as compared with the FR-nondys and control groups; for closed-class words at 23 and 35 months of age, the FR-nondys group's mean values are in between the mean of the FR-dys and control groups. Weak correlations were found between total vocabulary size, number of verbs, number and proportion of predicates at 23 months of age, and word and pseudoword reading fluency in Grades 2 and 3.

CONCLUSIONS

These results indicate that development of vocabulary is a significant though weak predictor of reading fluency and dyslexia; vocabulary size and proportion of verbs at 23 months of age, as well as proportion of closed-class words up to 35 months of age, seem to be the most sensitive indicators of delayed vocabulary development and later reading difficulties. There is no indication that FR for dyslexia by itself is related to vocabulary development.

A cross-cultural study showing deficits in gaze-language coordination during rapid automatized naming among individuals with ASD

Individuals with autism spectrum disorder (ASD) and their first-degree relatives demonstrate automaticity deficits reflected in reduced eye-voice coordination during rapid automatized naming (RAN), suggesting that RAN deficits may be a genetically meaningful marker of ASD language-related impairments. This study investigated whether RAN deficits in ASD extend to a language typologically distinct from English. Participants included 23 Cantonese-speaking individuals with ASD and 39 controls from Hong Kong (HK), and age- and IQ-comparable groups of previously-studied English-speaking individuals with ASD (n = 45) and controls (n = 44) from the US. Participants completed RAN on an eye tracker. Analyses examined naming time, error rate, measures of eye movement reflecting language automaticity, including eye-voice span (EVS; location of eyes versus the named item) and refixations. The HK-ASD group exhibited longer naming times and more refixations than HK-Controls, in a pattern similar to that observed in the US-ASD group. Cultural effects revealed that both HK groups showed longer EVS and more fixations than US groups. Naming time and refixation differences may be ASD-specific impairments spanning cultures/languages, whereas EVS and fixation frequency may be more variably impacted. A potential underlying mechanism of visual "stickiness" may be contributing to this breakdown in language automaticity in ASD.

Neural processing of vision and language in kindergarten is associated with prereading skills and predicts future literacy

The main objective of this longitudinal study was to investigate the neural predictors of reading acquisition. For this purpose, we followed a sample of 54 children from the end of kindergarten to the end of second grade. Preliterate children were tested for visual symbol (checkerboards, houses, faces, written words) and auditory language processing (spoken words) using a passive functional magnetic resonance imaging paradigm. To examine brain-behavior relationships, we also tested cognitive-linguistic prereading skills at kindergarten age and reading performance of 48 of the same children 2 years later. Face-selective response in the bilateral fusiform gyrus was positively associated with rapid automatized naming (RAN). Response to both spoken and written words at preliterate age was negatively associated with RAN in the dorsal temporo-parietal language system. Longitudinally, neural response to faces in the ventral stream predicted future reading fluency. Here, stronger neural activity in inferior and middle temporal gyri at kindergarten age was associated with higher reading performance. Our results suggest that interindividual differences in the neural system of language and reading affect literacy acquisition and thus might serve as a marker for successful reading acquisition in preliterate children.

Improving reading skills in children with dyslexia: efficacy studies on a newly proposed remedial intervention-repeated reading with vocal music masking (RVM)

In this work, two different studies are examined to evaluate the effectiveness of a novel intervention program for the improvement of reading ability in children with dyslexia, known as repeated reading with vocal music masking (RVM). The proposed remedial approach is inspired by Breznitz's original work. The studies assess a 5-week program of intensive RVM training in a pre-post-test clinical paradigm, as well as a longitudinal paradigm where it is compared to 8 months of the standard remediation program (SRP). The results of both studies support the efficacy of the newly proposed RVM method. Notably in the longitudinal study, the reading speed of children, as well as related phonological, visuo-attentional, and cognitive skills, and attitudes toward reading, were measured regularly. Significant improvements in reading efficiency and related skills were observed, as well as greater motivation to read after RVM training. A modeling of the data specifically linked executive and processing speed skills to be involved in RVM training, suggesting that RVM may help rebalance the phonological and orthographic coding procedures necessary for efficient reading. The short, intensive, and focused nature of RVM training makes it a viable and attractive intervention for clinical practice. As preliminary results are promising, RVM training may prove to be a valuable tool that clinicians can call upon to effectively treat reading fluency disorders, especially when standard programs do not provide results.

Overnight consolidation of speech sounds predicts decoding ability in skilled adult readers

PURPOSE

Phonological representations are important for reading. In the current work, we examine the relationship between speech-perceptual memory encoding and consolidation to reading ability in skilled adult readers.

METHOD

Seventy-three young adults (age 18-24) were first tested in their word and nonword reading ability, and then trained in the late evening to identify an unfamiliar speech sound contrast (Hindi retroflex-dental). Participants were assessed in their ability to perceive the target contrast immediately before training, after training, and 12 hours later.

RESULTS

While perceptual performance on the target at any time point was unassociated with reading ability, overnight changes to the post-training perceptual ability over the 12-hour delay was significantly associated with nonword reading (i.e. decoding) ability, but not real-word reading.

CONCLUSION

These results provide preliminary support for the hypothesis that individual differences in memory processes that update phonological representations following acoustic-phonetic exposure relate to decoding performance, including in adulthood.

Speech discrimination in infants at family risk of dyslexia: Group and individual-based analyses

Deficiencies in discriminating and identifying speech sounds have been widely attested in individuals with dyslexia as well as in young children at family risk (FR) of dyslexia. A speech perception deficit has been hypothesized to be causally related to reading and spelling difficulties. So far, however, early speech perception of FR infants has not been assessed at different ages within a single experimental design. Furthermore, a combination of group- and individual-based analyses has not been made. In this cross-sectional study, vowel discrimination of 6-, 8-, and 10-month-old Dutch FR infants and their nonrisk (no-FR) peers was assessed. Infants (N = 196) were tested on a native English /aː/-/eː/ and non-native English /ɛ/-/æ/ contrast using a hybrid visual habituation paradigm. Frequentist analyses were used to interpret group differences. Bayesian hierarchical modeling was used to classify individuals as speech sound discriminators. FR and no-FR infants discriminated the native contrast at all ages. However, individual classification of the no-FR infants suggests improved discrimination with age, but not for the FR infants. No-FR infants discriminated the non-native contrast at 6 and 10 months, but not at 8 months. FR infants did not show evidence of discriminating the contrast at any of the ages, with 0% being classified as discriminators. The group- and individual-based data are complementary and together point toward speech perception differences between the groups. The findings also indicate that conducting individual analyses on hybrid visual habituation outcomes is possible. These outcomes form a fruitful avenue for gaining more understanding of development, group differences, and prospective relationships.

The relation between neurofunctional and neurostructural determinants of phonological processing in pre-readers

Phonological processing skills are known as the most robust cognitive predictor of reading ability. Therefore, the neural determinants of phonological processing have been extensively investigated by means of either neurofunctional or neurostructural techniques. However, to fully understand how the brain represents and processes phonological information, there is need for studies that combine both methods. The present study applies such a multimodal approach with the aim of investigating the pre-reading relation between neural measures of auditory temporal processing, white matter properties of the reading network and phonological processing skills. We administered auditory steady-state responses, diffusion-weighted MRI scans and phonological awareness tasks in 59 pre-readers. Our results demonstrate that a stronger rightward lateralization of syllable-rate (4 Hz) processing coheres with higher fractional anisotropy in the left fronto-temporoparietal arcuate fasciculus. Both neural features each in turn relate to better phonological processing skills. As such, the current study provides novel evidence for the existence of a pre-reading relation between functional measures of syllable-rate processing, structural organization of the arcuate fasciculus and cognitive precursors of reading development. Moreover, our findings demonstrate the value of combining different neural techniques to gain insight in the underlying neural systems for reading (dis)ability.

On the Relationship Between General Auditory Sensitivity and Speech Perception: An Examination of Pitch and Lexical Tone Perception in 4- to 6-Year-Old Children

Purpose Theoretical models and substantial research have proposed that general auditory sensitivity is a developmental foundation for speech perception and language acquisition. Nonetheless, controversies exist about the effectiveness of general auditory training in improving speech and language skills. This research investigated the relationships among general auditory sensitivity, phonemic speech perception, and word-level speech perception via the examination of pitch and lexical tone perception in children. Method Forty-eight typically developing 4- to 6-year-old Cantonese-speaking children were tested on the discrimination of the pitch patterns of lexical tones in synthetic stimuli, discrimination of naturally produced lexical tones, and identification of lexical tone in familiar words. Results The findings revealed that accurate lexical tone discrimination and identification did not necessarily entail the accurate discrimination of nonlinguistic stimuli that followed the pitch levels and pitch shapes of lexical tones. Although pitch discrimination and tone discrimination abilities were strongly correlated, accuracy in pitch discrimination was lower than that in tone discrimination, and nonspeech pitch discrimination ability did not precede linguistic tone discrimination in the developmental trajectory. Conclusions Contradicting the theoretical models, the findings of this study suggest that general auditory sensitivity and speech perception may not be causally or hierarchically related. The finding that accuracy in pitch discrimination is lower than that in tone discrimination suggests that comparable nonlinguistic auditory perceptual ability may not be necessary for accurate speech perception and language learning. The results cast doubt on the use of nonlinguistic auditory perceptual training to improve children's speech, language, and literacy abilities.

The Impact of the Position of Phonemes and Lexical Status on Phonological Awareness in the Diglossic Arabic Language

This study aimed at examining the impact of phonemes and lexical status on phonological manipulation among pre-school children. Specifically, we tested the impact of phonemic positions (initial vs. final) and lexical status (shared, spoken, standard and pseudo-words) on phonemic isolation performance. Participants were 1012 children from the second year (K2) and third year (K2) in kindergarten. The results of the ANOVAs revealed significant effect of the phonemes' position on the phonemic isolation performance whereas the performance was easier with the initial rather than the final phonemes. Also, the repeated measure analysis showed that the lexical status also impacts the phonemic isolation performance. The performance in pseudo-words was lower than all the others. However, the other clusters of real words did not differ. The results are discussed in the light of previous findings in the literature and of differences in the syllabic structures of the words that may influence phonological awareness.

[Formula: see text] Developmental dyslexia: How taxonomic and thematic organization affect working memory recall

Semantic long-term memory (LTM) representations can be distinguished in two main classes: taxonomic (i.e., abstract) and thematic (i.e., concrete, experiential). In typically developing children, taxonomies are usually acquired after thematic representations. In the current study, we investigated how LTM semantic representations modulate working memory (WM) recall in children with developmental dyslexia (DD). A sample of children with DD from primary and secondary school paired with a control group for age, gender, schooling, and IQ was administered a semantic WM (SWM) dual task. Here, children had to listen to groups of lists composed of words semantically related (taxonomic, e.g., shop- drugstore-coffee; or thematic, e.g., light-heat-fire) or arbitrarily related, and afterward to recall the last words among each group. Both taxonomic and thematic organizations supported recall in the two groups of children. More specifically, data showed that in typically developing children the taxonomic organization boosted WM recall (vs. the thematic one). On the contrary, in children with DD, the taxonomic organization did not better support recall and yielded effects similar to thematic organization. In children with DD, abstract taxonomic knowledge seems to be less frequently used than thematic knowledge. Findings contribute to sketch memory functioning across different memory systems in DD.

Exploring the Overlap Between Dyslexia and Speech Sound Production Deficits

Purpose

Children with dyslexia have speech production deficits in a variety of spoken language contexts. In this article, we discuss the nature of speech production errors in children with dyslexia, including those who have a history of speech sound disorder and those who do not, to familiarize speech-language pathologists with speech production-specific risk factors that may help predict or identify dyslexia in young children.

Method

In this tutorial, we discuss the role of a phonological deficit in children with dyslexia and how this may manifest as speech production errors, sometimes in conjunction with a speech sound disorder but sometimes not. We also briefly review other factors outside the realm of phonology that may alert the speech-language pathologist to possible dyslexia.

Results

Speech-language pathologists possess unique knowledge that directly contributes to the identification and remediation of children with dyslexia. We present several clinical recommendations related to speech production deficits in children with dyslexia. We also review what is known about how and when children with speech sound disorder are most at risk for dyslexia.

Conclusion

Speech-language pathologists have a unique opportunity to assist in the identification of young children who are at risk for dyslexia.

Deficient Explicit Access to Phonological Representations Explains Phonological Fluency Difficulties in Greek Children With Dyslexia and/or Developmental Language Disorder

It is well-established that children with dyslexia and/or Developmental Language Disorder (hereafter children with DDLD) perform poorly on phonological tasks compared to typically developing (TD) children. However, there has been some debate as to whether their phonological deficit arises directly from an impairment in phonological representations, or instead from deficient access to (intact) phonological representations. This study tested the Degraded Phonological Representations Hypothesis and the Deficient Phonological Access Hypothesis using a task that is not often used with children with DDLD, namely phonological fluency. Both hypotheses predict that children with DDLD will retrieve fewer items than their TD peers in the phonological fluency task. However, while the Degraded Phonological Representations Hypothesis predicts smaller clusters of phonologically related items in children with DDLD, the Deficient Phonological Access Hypothesis predicts that the two groups will not differ in cluster size. How phonological fluency performance related to children's language, literacy, and phonological skills was investigated. Further, the specificity of a phonological fluency deficit in children with DDLD was tested using a nonverbal (design) fluency task. Sixty-six children with DDLD aged 7-12 years and 83 TD children aged 6-12 years, all monolingual Greek speakers, were tested on three phonological fluency categories, on nonverbal IQ, language, literacy, and phonological tasks, and on a design fluency task. The DDLD group produced significantly fewer correct responses and fewer switches compared to the TD group, but the two groups showed similar clustering and average cluster size. After controlling for age, children's language, literacy, and phonological skills significantly predicted the number of correct responses produced. The two groups did not differ significantly on the number of unique designs generated in the design fluency task. Furthermore, children with DDLD showed poorer phonological fluency performance relative to their TD peers even after design fluency performance was controlled, demonstrating the specificity of their phonological fluency deficit. This study adds to the theoretical debate on the locus of the phonological deficit in dyslexia and DLD. The findings support the hypothesis that the phonological deficit in dyslexia and DLD lies in deficient explicit access to intact phonological representations.

Does phonological distance impact quality of phonological representations? Evidence from Arabic diglossia

The study tested the impact of the phonological distance between Spoken Arabic (SpA) and Standard Arabic (StA) on quality of phonological representations among kindergarten, first-, second-, and sixth-grade Arabic-speaking children (N = 120). A pronunciation accuracy judgment task targeted three types of StA words that varied in extent of phonological distance from their form in SpA: (a) identical words, with an identical lexical-phonological form in StA and SpA; (b) cognate words, with partially overlapping phonological forms; items in this category varied in degree of phonological distance too; and (c) unique words with entirely different lexical-phonological forms. Multilevel Regression analysis showed that phonological distance had a significant impact on quality of phonological representations across all grades. Growth in quality of phonological representations was mainly noted between the three younger groups and the sixth-graders. Implications for the impact of phonological distance on phonological representations and on language and literacy development are discussed.

Predictive Models of Word Reading Fluency in Hebrew

This study examined a multi-componential approach to reading fluency in first and third grade Hebrew speaking children. Measures of naming speed, phonological awareness (PA), morphological awareness (MA), syntax awareness, and vocabulary were administered to first (N = 68) and third (N = 67) graders. Hierarchical regression models revealed that in both grades, naming speed accounted for most of the variance in each model. However, while in the first grade, word reading fluency was also predicted by vocabulary, in the third grade, both PA and MA were significant additional predictors. Predictive models of word reading fluency in Hebrew and applied implications are proposed.

Examining the double-deficit hypothesis in vowelized-transparent Arabic in a national representative sample of Grades 3 and 4

We examined the double-deficit hypothesis in Arabic by investigating the reading and cognitive profiles of readers with selective deficits in naming speed, phonological awareness, or both. In a nationally representative sample of 486 children in the third and fourth grades, we identified 171 children with reading difficulties: 20 (12%) were classified as having a phonological deficit, 31 (18%) as having a naming speed deficit, and 41 (24%) as having a double deficit. Differences between the subgroups extended to reading, cognitive, and linguistic processes beyond phonological and naming abilities. Children with a double deficit performed worse than those with a naming speed deficit but similar to those with a phonological deficit. Numerous unconfirmed theories led to an in-depth analysis of the nature of rapid automatized naming and its relation to orthographic processing. Surprisingly, our findings revealed that orthographic processing may be considered a novel and separate core deficit, suggesting a triple deficit in Arabic rather than a double deficit. The findings are discussed in light of the uniqueness and complexity of Arabic orthography and orthographic transparency in the Arabic language.

A Translational Framework of Educational Neuroscience in Learning Disorders

Neuroimaging has undergone enormous progress during the last two and a half decades. The combination of neuroscientific methods and educational practice has become a focus of interdisciplinary research in order to answer more applied questions. In this realm, conditions that hamper learning success and have deleterious effects in the population - such as learning disorders (LD) - could especially profit from neuroimaging findings. At the moment, however, there is an ongoing debate about how far neuroscientific research can go to inform the practical work in educational settings. Here, we put forward a theoretical translational framework as a method of conducting neuroimaging and bridging it to education, with a main focus on dyscalculia and dyslexia. Our work seeks to represent a theoretical but mainly empirical guide on the benefits of neuroimaging, which can help people working with different aspects of LD, who need to act collaboratively to reach the full potential of neuroimaging. We provide possible ideas regarding how neuroimaging can inform LD at different levels within our multidirectional framework, i.e., mechanisms, diagnosis/prognosis, training/intervention, and community/education. In addition, we discuss methodological, conceptual, and structural limitations that need to be addressed by future research.

Orthographic and Phonological Representations in the Fusiform Cortex

Mental and neural representations of words are at the core of understanding the cognitive and neural mechanisms of reading. Despite extensive studies, the nature of visual word representation remains highly controversial due to methodological limitations. In particular, it is unclear whether the fusiform cortex contains only abstract orthographic representation, or represents both lower and higher level orthography as well as phonology. Using representational similarity analysis, we integrated behavioral ratings, computational models of reading and visual object recognition, and neuroimaging data to examine the nature of visual word representations in the fusiform cortex. Our results provided clear evidence that the middle and anterior fusiform represented both phonological and orthographic information. Whereas lower level orthographic information was represented at every stage of the ventral visual stream, abstract orthographic information was increasingly represented along the posterior-to-anterior axis. Furthermore, the left and right hemispheres were tuned to high- and low-frequency orthographic information, respectively. These results help to resolve the long-standing debates regarding the role of the fusiform in reading, and have significant implications for the development of psychological, neural, and computational theories of reading.

Knockout Mice for Dyslexia Susceptibility Gene Homologs KIAA0319 and KIAA0319L have Unaffected Neuronal Migration but Display Abnormal Auditory Processing

Developmental dyslexia is a neurodevelopmental disorder that affects reading ability caused by genetic and non-genetic factors. Amongst the susceptibility genes identified to date, KIAA0319 is a prime candidate. RNA-interference experiments in rats suggested its involvement in cortical migration but we could not confirm these findings in Kiaa0319-mutant mice. Given its homologous gene Kiaa0319L (AU040320) has also been proposed to play a role in neuronal migration, we interrogated whether absence of AU040320 alone or together with KIAA0319 affects migration in the developing brain. Analyses of AU040320 and double Kiaa0319;AU040320 knockouts (dKO) revealed no evidence for impaired cortical lamination, neuronal migration, neurogenesis or other anatomical abnormalities. However, dKO mice displayed an auditory deficit in a behavioral gap-in-noise detection task. In addition, recordings of click-evoked auditory brainstem responses revealed suprathreshold deficits in wave III amplitude in AU040320-KO mice, and more general deficits in dKOs. These findings suggest that absence of AU040320 disrupts firing and/or synchrony of activity in the auditory brainstem, while loss of both proteins might affect both peripheral and central auditory function. Overall, these results stand against the proposed role of KIAA0319 and AU040320 in neuronal migration and outline their relationship with deficits in the auditory system.

How African American English-Speaking First Graders Segment and Rhyme Words and Nonwords With Final Consonant Clusters

Purpose

This study explored how typically developing 1st grade African American English (AAE) speakers differ from mainstream American English (MAE) speakers in the completion of 2 common phonological awareness tasks (rhyming and phoneme segmentation) when the stimulus items were consonant–vowel–consonant–consonant (CVCC) words and nonwords.

Method

Forty-nine 1st graders met criteria for 2 dialect groups: AAE and MAE. Three conditions were tested in each rhyme and segmentation task: Real Words No Model, Real Words With a Model, and Nonwords With a Model.

Results

The AAE group had significantly more responses that rhymed CVCC words with consonant–vowel–consonant words and segmented CVCC words as consonant–vowel–consonant than the MAE group across all experimental conditions. In the rhyming task, the presence of a model in the real word condition elicited more reduced final cluster responses for both groups. In the segmentation task, the MAE group was at ceiling, so only the AAE group changed across the different stimulus presentations and reduced the final cluster less often when given a model.

Conclusion

Rhyming and phoneme segmentation performance can be influenced by a child's dialect when CVCC words are used.

Beyond Auditory Sensory Processing Deficits: Lexical Tone Perception Deficits in Chinese Children With Developmental Dyslexia

Increasing evidence suggests that children with developmental dyslexia exhibit a deficit not only at the segmental level of phonological processing but also, by extension, at the suprasegmental level. However, it remains unclear whether such a suprasegmental phonological processing deficit is due to a difficulty in processing acoustic cues of speech rhythm, such as rise time and intensity. This study set out to investigate to what extent suprasegmental phonological processing (i.e., Cantonese lexical tone perception) and rise time sensitivity could distinguish Chinese children with dyslexia from typically developing children. Sixteen children with dyslexia and 44 age-matched controls were administered a Cantonese lexical tone perception task, psychoacoustic tasks, a nonverbal reasoning ability task, and word reading and dictation tasks. Children with dyslexia performed worse than controls on Cantonese lexical tone perception, rise time, and intensity. Furthermore, Cantonese lexical tone perception appeared to be a stable indicator that distinguishes children with dyslexia from controls, even after controlling for basic auditory processing skills. These findings suggest that suprasegmental phonological processing (i.e., lexical tone perception) is a potential factor that accounts for reading difficulty in Chinese.

Electrophysiological and phonological change detection measures of auditory word processing in normal Persian-speaking children

OBJECTIVE

Auditory phoneme discrimination is a basic and important prerequisite for acquiring speech, reading, and spelling skills. Children, who are unable to perceive auditory phoneme discrimination, cannot develop phonemic representations. Therefore, the early identification of these deficits and application of effective therapeutic approaches is a necessity. We need to assess appropriately word or sound discrimination in normal populations using an objective passive task such as mismatch negativity (MMN). Therefore, the aim of the present study was to investigate MMN responses using speech stimuli (words) in 6-7 year-old normal Persian-speaking children.

METHODS

Ten right-handed Persian-speaking children with normal visual and auditory acuity, aged from 6 to 7 years, participated in the study. Recording of electroencephalography (EEG) was done by 64 A g/AgCl electrodes. A new auditory paradigm was used with three deviant stimuli (/gam/,/jam/, and/tam/) which differed in the first consonant from a repeated standard word (/dam/). A total of 1500 stimuli, 750 standards and 750 deviants (250 each deviant), were presented by Cogent 2000 running in MATLAB software using two loud speakers.

RESULTS

MMN peaked over the fronto-central sites at around 380-424 ms after the onset of the stimulus. The comparison of the MMN amplitudes elicited by three deviants revealed a significant "initial phoneme type" effect in Fz and Cz (p < 0.05). This negativity was found to be larger for manner and voicing deviants compared with that of the place of articulation (p < 0.001) on midline scalps. The comparison of the MMN latencies revealed no significant main effect of all variables (p > 0.05). Also, the results revealed that only the MMN amplitude for the/gam/deviant correlated with the percentage of correct responses (R = -0.86, p < 0.01).

CONCLUSION

The current study showed that words can elicit MMN responses in ∼200 ms after the onset of changes. We can objectively evaluate children's neural speech sound discrimination using the developed paradigm in a natural word context. This paradigm can be useful objectively for investigating distinctive features of sounds and phonological discrimination development in normal children.

Neural initialization of audiovisual integration in prereaders at varying risk for developmental dyslexia

Learning letter-speech sound correspondences is a major step in reading acquisition and is severely impaired in children with dyslexia. Up to now, it remains largely unknown how quickly neural networks adopt specific functions during audiovisual integration of linguistic information when prereading children learn letter-speech sound correspondences. Here, we simulated the process of learning letter-speech sound correspondences in 20 prereading children (6.13-7.17 years) at varying risk for dyslexia by training artificial letter-speech sound correspondences within a single experimental session. Subsequently, we acquired simultaneously event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) scans during implicit audiovisual presentation of trained and untrained pairs. Audiovisual integration of trained pairs correlated with individual learning rates in right superior temporal, left inferior temporal, and bilateral parietal areas and with phonological awareness in left temporal areas. In correspondence, a differential left-lateralized parietooccipitotemporal ERP at 400 ms for trained pairs correlated with learning achievement and familial risk. Finally, a late (650 ms) posterior negativity indicating audiovisual congruency of trained pairs was associated with increased fMRI activation in the left occipital cortex. Taken together, a short (<30 min) letter-speech sound training initializes audiovisual integration in neural systems that are responsible for processing linguistic information in proficient readers. To conclude, the ability to learn grapheme-phoneme correspondences, the familial history of reading disability, and phonological awareness of prereading children account for the degree of audiovisual integration in a distributed brain network. Such findings on emerging linguistic audiovisual integration could allow for distinguishing between children with typical and atypical reading development. Hum Brain Mapp 38:1038-1055, 2017. © 2016 Wiley Periodicals, Inc.

Differences between Dyslexic and Non-Dyslexic Children in the Performance of Phonological Visual-Auditory Recognition Tasks: An Eye-Tracking Study

The object of this study was to explore further phonological visual-auditory recognition tasks in a group of fifty-six healthy children (mean age: 9.9 ± 0.3) and to compare these data to those recorded in twenty-six age-matched dyslexic children (mean age: 9.8 ± 0.2). Eye movements from both eyes were recorded using an infrared video-oculography system (MobileEBT® e(y)e BRAIN). The recognition task was performed under four conditions in which the target object was displayed either with phonologically unrelated objects (baseline condition), or with cohort or rhyme objects (cohort and rhyme conditions, respectively), or both together (rhyme + cohort condition). The percentage of the total time spent on the targets and the latency of the first saccade on the target were measured. Results in healthy children showed that the percentage of the total time spent in the baseline condition was significantly longer than in the other conditions, and that the latency of the first saccade in the cohort condition was significantly longer than in the other conditions; interestingly, the latency decreased significantly with the increasing age of the children. The developmental trend of phonological awareness was also observed in healthy children only. In contrast, we observed that for dyslexic children the total time spent on the target was similar in all four conditions tested, and also that they had similar latency values in both cohort and rhyme conditions. These findings suggest a different sensitivity to the phonological competitors between dyslexic and non-dyslexic children. Also, the eye-tracking technique provides online information about phonological awareness capabilities in children.

Visual sign phonology: insights into human reading and language from a natural soundless phonology

Among the most prevailing assumptions in science and society about the human reading process is that sound and sound-based phonology are critical to young readers. The child's sound-to-letter decoding is viewed as universal and vital to deriving meaning from print. We offer a different view. The crucial link for early reading success is not between segmental sounds and print. Instead the human brain's capacity to segment, categorize, and discern linguistic patterning makes possible the capacity to segment all languages. This biological process includes the segmentation of languages on the hands in signed languages. Exposure to natural sign language in early life equally affords the child's discovery of silent segmental units in visual sign phonology (VSP) that can also facilitate segmental decoding of print. We consider powerful biological evidence about the brain, how it builds sound and sign phonology, and why sound and sign phonology are equally important in language learning and reading. We offer a testable theoretical account, reading model, and predictions about how VSP can facilitate segmentation and mapping between print and meaning. We explain how VSP can be a powerful facilitator of all children's reading success (deaf and hearing)-an account with profound transformative impact on learning to read in deaf children with different language backgrounds. The existence of VSP has important implications for understanding core properties of all human language and reading, challenges assumptions about language and reading as being tied to sound, and provides novel insight into a remarkable biological equivalence in signed and spoken languages. WIREs Cogn Sci 2016, 7:366-381. doi: 10.1002/wcs.1404 For further resources related to this article, please visit the WIREs website.

Children's comprehension of an unfamiliar speaker accent: a review

BACKGROUND

The effect of speaker accent on listeners' comprehension has become a key focus of research given the increasing cultural diversity of society and the increased likelihood of an individual encountering a clinician with an unfamiliar accent.

AIMS

To review the studies exploring the effect of an unfamiliar accent on language comprehension in typically developing (TD) children and in children with speech and language difficulties. This review provides a methodological analysis of the relevant studies by exploring the challenges facing this field of research and highlighting the current gaps in the literature.

METHODS & PROCEDURES

A total of nine studies were identified using a systematic search and organized under studies investigating the effect of speaker accent on language comprehension in (1) TD children and (2) children with speech and/or language difficulties.

MAIN CONTRIBUTION

This review synthesizes the evidence that an unfamiliar speaker accent may lead to a breakdown in language comprehension in TD children and in children with speech difficulties. Moreover, it exposes the inconsistencies found in this field of research and highlights the lack of studies investigating the effect of speaker accent in children with language deficits.

CONCLUSIONS & IMPLICATIONS

Overall, research points towards a developmental trend in children's ability to comprehend accent-related variations in speech. Vocabulary size, language exposure, exposure to different accents and adequate processing resources (e.g. attention) seem to play a key role in children's ability to understand unfamiliar accents. This review uncovered some inconsistencies in the literature that highlight the methodological issues that must be considered when conducting research in this field. It explores how such issues may be controlled in order to increase the validity and reliability of future research. Key clinical implications are also discussed.

Auditory perception of non-sense and familiar Bengali rhyming words in children with and without SLD

BACKGROUND

Rhyming ability is among the earliest metaphonological skills to be acquired during the process of speech and language acquisition. Metalinguistic skills, particularly metaphonological skills, greatly influence language learning during early, school grades and reportedly children with learning disorders are poor at these skills.

AIM AND OBJECTIVES

To develop and validate a Bengali rhyming checklist and study the auditory perception of non-sense and familiar Bengali rhyming words in children with and without specific learning disability (SLD).

METHOD

60 children, age range 8-11years, participated in two groups; group-A included children with SLD and group-B, typically developing children (TDC). All participants were native Bengali speakers, attending regular school, with hearing sensitivity less than 25dBHL, no history of ear discharge and middle socioeconomic background. A rhyming checklist was developed in Bengali, consisting of familiar (section-A) and non-sense (section-B) words. Test-retest reliability and validity measures were obtained. The items on the checklist were audio recorded and presented to the participants in a rhyming judgment task in one to one set up. Scores were obtained and statistically analyzed using SPSS software (version-11.0).

RESULT

Children with SLD scored significantly low on the rhyming judgment task as against TDC (p<.05) for both familiar and non-sense words. Children with SLD performed significantly better on familiar word rhyming judgment task against non-sense words (p<.05). TDC showed no significant difference on familiar and non-sense words rhyming judgment tasks (p>.05).

CONCLUSION

Semantic content influences rhyming perception in children with SLD but has no significant effect on TDC. The developed rhyming checklist may be used as a screening tool for children at risk of SLD at primary school grades. Rhyming activities may be utilized by teachers and parents, to promote language learning in young learners.

Improving reading skills in students with dyslexia: the efficacy of a sublexical training with rhythmic background

The core deficit underlying developmental dyslexia (DD) has been identified in difficulties in dynamic and rapidly changing auditory information processing, which contribute to the development of impaired phonological representations for words. It has been argued that enhancing basic musical rhythm perception skills in children with DD may have a positive effect on reading abilities because music and language share common mechanisms and thus transfer effects from the former to the latter are expected to occur. A computer-assisted training, called Rhythmic Reading Training (RRT), was designed in which reading exercises are combined with rhythm background. Fourteen junior high school students with DD took part to 9 biweekly individual sessions of 30 min in which RRT was implemented. Reading improvements after the intervention period were compared with ones of a matched control group of 14 students with DD who received no intervention. Results indicated that RRT had a positive effect on both reading speed and accuracy and significant effects were found on short pseudo-words reading speed, long pseudo-words reading speed, high frequency long words reading accuracy, and text reading accuracy. No difference in rhythm perception between the intervention and control group were found. Findings suggest that rhythm facilitates the development of reading skill because of the temporal structure it imposes to word decoding.

Word recognition and nonword repetition in children with language disorders: the effects of neighborhood density, lexical frequency, and phonotactic probability

PURPOSE

The effects of neighborhood density (ND) and lexical frequency on word recognition and the effects of phonotactic probability (PP) on nonword repetition (NWR) were examined to gain insight into processing at the lexical and sublexical levels in typically developing (TD) children and children with developmental language problems.

METHOD

Tasks measuring NWR and word recognition were administered to 5 groups of children: 2 groups of TD children (5 and 8 years old), children with specific language impairment (SLI), children with reading impairment (RI), and children with SLI+RI (all 7-8 years old).

RESULTS

High ND had a negative effect on word recognition in the older TD children and in the children with RI only. There was no ND effect in the younger children or in the children with SLI, who all had lower receptive vocabulary scores than the age-matched TD children and the RI groups. For all groups, NWR items with low PP were more difficult to repeat than items with high PP. This effect was especially pronounced in children with RI.

CONCLUSION

Both the stage of vocabulary development and the type of language impairment (SLI or RI) impact the way ND and PP affect word recognition and NWR.

The level of audiovisual print-speech integration deficits in dyslexia

The classical phonological deficit account of dyslexia is increasingly linked to impairments in grapho-phonological conversion, and to dysfunctions in superior temporal regions associated with audiovisual integration. The present study investigates mechanisms of audiovisual integration in typical and impaired readers at the critical developmental stage of adolescence. Congruent and incongruent audiovisual as well as unimodal (visual only and auditory only) material was presented. Audiovisual presentations were single letters and three-letter (consonant-vowel-consonant) stimuli accompanied by matching or mismatching speech sounds. Three-letter stimuli exhibited fast phonetic transitions as in real-life language processing and reading. Congruency effects, i.e. different brain responses to congruent and incongruent stimuli were taken as an indicator of audiovisual integration at a phonetic level (grapho-phonological conversion). Comparisons of unimodal and audiovisual stimuli revealed basic, more sensory aspects of audiovisual integration. By means of these two criteria of audiovisual integration, the generalizability of audiovisual deficits in dyslexia was tested. Moreover, it was expected that the more naturalistic three-letter stimuli are superior to single letters in revealing group differences. Electrophysiological and hemodynamic (EEG and fMRI) data were acquired simultaneously in a simple target detection task. Applying the same statistical models to event-related EEG potentials and fMRI responses allowed comparing the effects detected by the two techniques at a descriptive level. Group differences in congruency effects (congruent against incongruent) were observed in regions involved in grapho-phonological processing, including the left inferior frontal and angular gyri and the inferotemporal cortex. Importantly, such differences also emerged in superior temporal key regions. Three-letter stimuli revealed stronger group differences than single letters. No significant differences in basic measures of audiovisual integration emerged. Convergence of hemodynamic and electrophysiological signals appeared to be limited and mainly occurred for highly significant and large effects in visual cortices. The findings suggest efficient superior temporal tuning to audiovisual congruency in controls. In impaired readers, however, grapho-phonological conversion is effortful and inefficient, although basic audiovisual mechanisms seem intact. This unprecedented demonstration of audiovisual deficits in adolescent dyslexics provides critical evidence that the phonological deficit might be explained by impaired audiovisual integration at a phonetic level, especially for naturalistic and word-like stimulation.

Best of both worlds: promise of combining brain stimulation and brain connectome

Transcranial current brain stimulation (tCS) is becoming increasingly popular as a non-pharmacological non-invasive neuromodulatory method that alters cortical excitability by applying weak electrical currents to the scalp via a pair of electrodes. Most applications of this technique have focused on enhancing motor and learning skills, as well as a therapeutic agent in neurological and psychiatric disorders. In these applications, similarly to lesion studies, tCS was used to provide a causal link between a function or behavior and a specific brain region (e.g., primary motor cortex). Nonetheless, complex cognitive functions are known to rely on functionally connected multitude of brain regions with dynamically changing patterns of information flow rather than on isolated areas, which are most commonly targeted in typical tCS experiments. In this review article, we argue in favor of combining tCS method with other neuroimaging techniques (e.g., fMRI, EEG) and by employing state-of-the-art connectivity data analysis techniques (e.g., graph theory) to obtain a deeper understanding of the underlying spatiotemporal dynamics of functional connectivity patterns and cognitive performance. Finally, we discuss the possibilities of using these combined techniques to investigate the neural correlates of human creativity and to enhance creativity.

Investigating graph comprehension in students with dyslexia: an eye tracking study

The purpose of this study was to examine graph comprehension in college students with developmental dyslexia. We investigated how graph types (line, vertical bar, and horizontal bar graphs), graphic patterns (single and double graphic patterns), and question types (point locating and comparison questions) differentially affect graph comprehension of students with and without dyslexia. Groups were compared for (1) reaction times for answering comprehension questions based on graphed data and (2) eye gaze times for specific graph subregions (x-axis, y-axis, pattern, legend, question, and answer). Dyslexic readers were significantly slower in their graph comprehension than their peers with group differences becoming more robust with the increasing complexity of graphs and tasks. In addition, dyslexic readers' initial eye gaze viewing times for linguistic subregions (question and answer) and total viewing times for both linguistic (question and answer) and nonlinguistic (pattern) subregions were significantly longer than their control peers' times. In spite of using elementary-level paragraphs for comprehension and simple graph forms, young adults with dyslexia needed more time to process linguistic and nonlinguistic stimuli. These findings are discussed relative to theories proposed to address fundamental processing deficits in individuals with dyslexia.

Magnocellular-dorsal pathway and sub-lexical route in developmental dyslexia

Although developmental dyslexia (DD) is frequently associate with a phonological deficit, the underlying neurobiological cause remains undetermined. Recently, a new model, called "temporal sampling framework" (TSF), provided an innovative prospect in the DD study. TSF suggests that deficits in syllabic perception at a specific temporal frequencies are the critical basis for the poor reading performance in DD. This approach was presented as a possible neurobiological substrate of the phonological deficit of DD but the TSF can also easily be applied to the visual modality deficits. The deficit in the magnocellular-dorsal (M-D) pathway - often found in individuals with DD - fits well with a temporal oscillatory deficit specifically related to this visual pathway. This study investigated the visual M-D and parvocellular-ventral (P-V) pathways in dyslexic and in chronological age and IQ-matched normally reading children by measuring temporal (frequency doubling illusion) and static stimuli sensitivity, respectively. A specific deficit in M-D temporal oscillation was found. Importantly, the M-D deficit was selectively shown in poor phonological decoders. M-D deficit appears to be frequent because 75% of poor pseudo-word readers were at least 1 SD below the mean of the controls. Finally, a replication study by using a new group of poor phonological decoders and reading level controls suggested a crucial role of M-D deficit in DD. These results showed that a M-D deficit might impair the sub-lexical mechanisms that are critical for reading development. The possible link between these findings and TSF is discussed.

Executive functions in developmental dyslexia

The present study was aimed at investigating different aspects of Executive Functions (EF) in children with Developmental Dyslexia (DD). A neuropsychological battery tapping verbal fluency, spoonerism, attention, verbal shifting, short-term and working memory was used to assess 60 children with DD and 65 with typical reading (TR) abilities. Compared to their controls, children with DD showed deficits in several EF domains such as verbal categorical and phonological fluency, visual-spatial and auditory attention, spoonerism, verbal and visual short-term memory, and verbal working memory. Moreover, exploring predictive relationships between EF measures and reading, we found that spoonerism abilities better explained word and non-word reading deficits. Although to a lesser extent, auditory and visual-spatial attention also explained the increased percentage of variance related to reading deficit. EF deficits found in DD are interpreted as an expression of a deficient functioning of the Central Executive System and are discussed in the context of the recent temporal sampling theory.

Language-dependent performance on the letter fluency task in patients with schizophrenia

Two types of verbal fluency tasks (letter fluency task; LFT, category fluency task; CFT) have been widely used to assess cognitive function in people with psychiatric diseases including schizophrenia. The task demand of the LFT is considered to vary across languages, as the cognitive process largely relies on sound and writing systems. Specifically, a sound unit for a letter (s) and a manner of association between them are assumed to be related with the performance. In the current study, three analyses have been conducted to examine this issue, using Japanese, Turkish, and English-speaking patients with schizophrenia. It was hypothesized that severity of letter fluency impairment would be in the order of Japanese, Turkish, and English speaking patients according to the inflexibility of a word search. First, performance on the LFT and the CFT was compared among Japanese (N=40), Turkish (N=30), and the US (N=31) patients (Analysis 1). A significant difference was found between the US and other two groups only in the LFT. Second, verbal fluency performance was compared between Japanese and Turkish patients by contrasting the degree of disassociations from normal controls (Japanese: N=20, Turkish: N=30) (Analysis 2). In Japanese patients, performance on the LFT was more severely impaired compared to that on the CFT while the opposite trend was found in the Turkish counterpart, suggesting that letter fluency performance was more degraded in Japanese patients. Finally, Analysis 3 was conducted to examine the relative order of letter fluency impairment among Japanese, Turkish and English-speaking patients. Disassociation in English users with schizophrenia was estimated based on previous meta-analytic reviews. The effect size (ES) for the letter fluency deficit was the largest in the Japanese sample, while the other two groups share similar ESs. The results from the three analyses partially supported the hypothesis for the severity of the letter fluency impairment in patients with schizophrenia. The language-dependency of letter fluency impairment was thought to be explained by the theoretical model built on unique properties of sound and writing systems. The considerations presented here would provide useful information for optimizing the portability of cognitive tasks across languages.

Intact but less accessible phonetic representations in adults with dyslexia

Dyslexia is a severe and persistent reading and spelling disorder caused by impairment in the ability to manipulate speech sounds. We combined functional magnetic resonance brain imaging with multivoxel pattern analysis and functional and structural connectivity analysis in an effort to disentangle whether dyslexics' phonological deficits are caused by poor quality of the phonetic representations or by difficulties in accessing intact phonetic representations. We found that phonetic representations are hosted bilaterally in primary and secondary auditory cortices and that their neural quality (in terms of robustness and distinctness) is intact in adults with dyslexia. However, the functional and structural connectivity between the bilateral auditory cortices and the left inferior frontal gyrus (a region involved in higher-level phonological processing) is significantly hampered in dyslexics, suggesting deficient access to otherwise intact phonetic representations.

Intact but less accessible phonetic representations in adults with dyslexia

Dyslexia is a severe and persistent reading and spelling disorder caused by impairment in the ability to manipulate speech sounds. We combined functional magnetic resonance brain imaging with multivoxel pattern analysis and functional and structural connectivity analysis in an effort to disentangle whether dyslexics' phonological deficits are caused by poor quality of the phonetic representations or by difficulties in accessing intact phonetic representations. We found that phonetic representations are hosted bilaterally in primary and secondary auditory cortices and that their neural quality (in terms of robustness and distinctness) is intact in adults with dyslexia. However, the functional and structural connectivity between the bilateral auditory cortices and the left inferior frontal gyrus (a region involved in higher-level phonological processing) is significantly hampered in dyslexics, suggesting deficient access to otherwise intact phonetic representations.