Functional disruption in the organization of the brain for reading in dyslexia

Frequency-band specific directed connectivity networks reveal functional disruptions and pathogenic patterns in temporal lobe epilepsy: a MEG study

This study investigates the network mechanisms of temporal lobe epilepsy (TLE) using MEG data, focusing on directed connectivity networks across different frequency bands. Unlike previous studies that primarily localize epileptogenic zones, this research aims to explore whole-brain network differences between left TLE (lTLE), right TLE (rTLE), and healthy controls (HCs). MEG data from 13 lTLE patients, 21 rTLE patients, and 14 HCs were source-reconstructed to 116 brain regions (AAL116). Directed Transfer Function (DTF) was used to construct directed connectivity networks, followed by networks and graph-theoretical analyses. The results indicate that, compared to HCs, TLE subjects exhibited a significant increase in average connectivity strength in the Low Gamma band. The connectivity patterns across frequency bands in TLE patients were found to be unstable. Both HC and TLE subjects demonstrated left hemisphere lateralization. In the mid-to-low frequency bands, TLE subjects showed increases in global clustering coefficient (GCC), global characteristic path length (GCPL), and local efficiency (LE) compared to HCs, which is attributed to enhanced synchronization between local brain regions in TLE subjects.

The structural covariance of reading-related brain regions in adults and children with typical or poor reading skills

Structural covariance (SC) is a promising approach for studying brain organization in the context of literacy and developmental disorders, offering insights into both structural and functional underpinnings and potential experience-dependent co-development of functional brain networks. Here, we explore the influence of maturation and reading skill on SC in reading-related brain regions. Whole-brain SC analyses were conducted for six key regions of the reading network, including an anterior and posterior subdivision of the visual word form area (VWFA). To study maturational effects, SC was compared between typical-reading adults (N = 134, 25.3 ± 4 yrs) and children (N = 110, 9.6 ± 1.6 yrs). The impact of reading skills on SC was assessed by comparing typical-reading children (N = 110, 9.6 ± 1.6 yrs) to children with poor reading skills (N = 68, 10.2 ± 1.4 yrs). Our results showed significant SC between reading-related brain regions in typical-reading adults. Further, we observed significant SC between the posterior VWFA and the occipital cortex, and between the anterior VWFA and the superior temporal and inferior frontal gyri. There was no indication of a major change in SC within the reading network related to maturation. However, we observed higher SC between the inferior parietal lobule and other reading-related brain regions in children with typical compared to poor reading skills.

Small or absent Visual Word Form Area is a trait of dyslexia

Understanding the balance between plastic and persistent traits in the dyslexic brain is critical for developing effective interventions. This longitudinal intervention study examines the Visual Word Form Area (VWFA) in dyslexic and typical readers, exploring how this key component of the brain's reading circuitry changes with learning. We found that dyslexic readers show significant differences in VWFA presence, size, and tuning properties compared to typical readers. While reading intervention improved reading skills and increased VWFA size, disparities persisted, suggesting that VWFA abnormalities are an enduring trait of dyslexia. Notably, we found that even with sufficient intervention to close the reading skill gap, dyslexic readers are still expected to have smaller VWFAs. Our results reveal intervention-driven long-term neural and behavioral changes, while also elucidating stable differences in the functional architecture of the dyslexic brain. This provides new insights into the potential and limitations of learning-induced plasticity in the human visual cortex.

Reading disability is characterized by reduced print-speech convergence

Reading disability (RD) may be characterized by reduced print-speech convergence, which is the extent to which neurocognitive processes for reading and hearing words overlap. We examined how print-speech convergence changes from children (mean age: 11.07+0.48) to adults (mean age: 21.33+1.80) in 86 readers with or without RD. The participants were recruited in elementary schools and associate degree colleges in China (from 2020 to 2021). Three patterns of abnormalities were revealed: (1) persistent reduction of print-speech convergence in the left inferior parietal cortex in both children and adults with RD, suggesting a neural signature of RD; (2) reduction of print-speech convergence in the left inferior frontal gyrus only evident in children but not adults with RD, suggesting a developmental delay; and (3) increased print-speech convergence in adults with RD than typical adults in the bilateral cerebella/fusiform, suggesting compensations. It provides insights into developmental differences in brain functional abnormalities in RD.

Delineating Region-Specific contributions and connectivity patterns for semantic association and categorization through ROI and Granger causality analysis

The neural mechanisms supporting semantic association and categorization are examined in this study. Semantic association involves linking concepts through shared themes, events, or scenes, while semantic categorization organizes meanings hierarchically based on defining features. Twenty-three adults participated in an fMRI study performing categorization and association judgment tasks. Results showed stronger activation in the inferior frontal gyrus during association and marginally weaker activation in the posterior middle temporal gyrus (pMTG) during categorization. Granger causality analysis revealed bottom-up connectivity from the visual cortex to the hippocampus during semantic association, whereas semantic categorization exhibited strong reciprocal connections between the pMTG and frontal semantic control regions, together with information flow from the visual association area and hippocampus to the pars triangularis. We propose that demands on semantic retrieval, precision of semantic representation, perceptual experiences and world knowledge result in observable differences between these two semantic relations.

The relationship between digit ratio (2D:4D) and intelligence levels in specific learning disorders

BACKGROUND

Higher prenatal testosterone exposure regulates brain development and affects learning and intelligence directly. The digit ratio (2D:4D) is regarded as an indicator of prenatal testosterone exposure. This study aims to investigate the 2D:4D ratios and intelligence levels in individuals with specific learning disorders (SLD) and compare the ratios with healthy subjects.

METHODS

The study included a total of 117 patients diagnosed with SLD and 67 healthy controls. We measured the 2D:4D ratios and administered the Wechsler-Intelligence Scale for Children-Revised to assess intelligence quotient (IQ) scores in the SLD group. Sociodemographic data was obtained for both patients and healthy subjects and compared in both groups, as well as 2D:4D ratios.

RESULTS

Compared to healthy controls, both-hand 2D:4D ratios were found to be lower in the SLD group. In addition, male and female participants with SLD showed lower 2D:4D ratios in both hands than controls. The total scores on the WISC-R were found to decrease as the right-hand 2D:4D ratios and the age increased in the SLD group.

CONCLUSION

Our findings add to the literature examining the influence of prenatal testosterone exposure on learning and intelligence in the SLD sample. Further research in this domain may yield valuable insights into the underlying mechanisms and potential clinical implications for the management of SLDs examining additional variables that could potentially impact alongside the impact of sex hormones on brain development.

Multiple Types of Developmental Dyslexias in a Shallow Orthography: Principles for Diagnostic Screening in Italian

A new dyslexia screening test for Italian, Tiltan-IT, is presented. The test was developed based on an integrated dual-route model of reading, which describes in detail specific mechanisms underpinning early visual processes as well as the lexical and the sublexical routes. The principle according to which the test was developed is that each dyslexia type is manifested in different kinds of errors and in different kinds of stimuli, and we therefore included stimuli sensitive to each dyslexia type in the test. Tiltan-IT is a reading aloud test that includes word, nonword, and word pair lists. The test was administered to 618 Italian-speaking children (2nd-8th grade). Each error produced by the children was classified through the coding scheme developed to detect the different types of dyslexias described by the reading model. The Tiltan-IT was able to identify 110 children with dyslexia. The identified dyslexia types included letter position dyslexia, attentional dyslexia, letter identity dyslexia, surface dyslexia, vowel dyslexia, consonant conversion dyslexia, multi-letter phonological dyslexia, voicing dyslexia. The results confirm that the selection of items in the Tiltan-IT enabled the detection of the wide variety of dyslexias in Italian, some of them for the first time, adding evidence for the cross-linguistic validity of multiple types of developmental dyslexias and for the dual-route model of reading.

Neurocognitive mechanisms of co-occurring math difficulties in dyslexia: Differences in executive function and visuospatial processing

Children with dyslexia frequently also struggle with math. However, studies of reading disability (RD) rarely assess math skill, and the neurocognitive mechanisms underlying co-occurring reading and math disability (RD+MD) are not clear. The current study aimed to identify behavioral and neurocognitive factors associated with co-occurring MD among 86 children with RD. Within this sample, 43% had co-occurring RD+MD and 22% demonstrated a possible vulnerability in math, while 35% had no math difficulties (RD-Only). We investigated whether RD-Only and RD+MD students differed behaviorally in their phonological awareness, reading skills, or executive functions, as well as in the brain mechanisms underlying word reading and visuospatial working memory using functional magnetic resonance imaging (fMRI). The RD+MD group did not differ from RD-Only on behavioral or brain measures of phonological awareness related to speech or print. However, the RD+MD group demonstrated significantly worse working memory and processing speed performance than the RD-Only group. The RD+MD group also exhibited reduced brain activations for visuospatial working memory relative to RD-Only. Exploratory brain-behavior correlations along a broad spectrum of math ability revealed that stronger math skills were associated with greater activation in bilateral visual cortex. These converging neuro-behavioral findings suggest that poor executive functions in general, including differences in visuospatial working memory, are specifically associated with co-occurring MD in the context of RD. RESEARCH HIGHLIGHTS: Children with reading disabilities (RD) frequently have a co-occurring math disability (MD), but the mechanisms behind this high comorbidity are not well understood. We examined differences in phonological awareness, reading skills, and executive function between children with RD only versus co-occurring RD+MD using behavioral and fMRI measures. Children with RD only versus RD+MD did not differ in their phonological processing, either behaviorally or in the brain. RD+MD was associated with additional behavioral difficulties in working memory, and reduced visual cortex activation during a visuospatial working memory task.

The odd one out - Orthographic oddball processing in children with poor versus typical reading skills in a fast periodic visual stimulation EEG paradigm

The specialization of left ventral occipitotemporal brain regions to automatically process word forms develops with reading acquisition and is diminished in children with poor reading skills (PR). Using a fast periodic visual oddball stimulation (FPVS) design during electroencephalography (EEG), we examined the level of sensitivity and familiarity to word form processing in ninety-two children in 2nd and 3rd grade with varying reading skills (n = 35 for PR, n = 40 for typical reading skills; TR). To test children's level of "sensitivity", false font (FF) and consonant string (CS) oddballs were embedded in base presentations of word (W) stimuli. "Familiarity" was examined by presenting letter string oddballs with increasing familiarity (CS, pseudoword - PW, W) in FF base stimuli. Overall, our results revealed stronger left-hemispheric coarse sensitivity effects ("FF in W" > "CS in W") in TR than in PR in both topographic and oddball frequency analyses. Further, children distinguished between orthographically legal and illegal ("W/PW in FF" > "CS in FF") but not yet between lexical and non-lexical ("W in FF" vs "PW in FF") word forms. Although both TR and PR exhibit visual sensitivity and can distinguish between orthographically legal and illegal letter strings, they still struggle with nuanced lexical distinctions. Moreover, the strength of sensitivity is linked to reading proficiency. Our work adds to established knowledge in the field to characterize the relationship between print tuning and reading skills and suggests differences in the developmental progress to automatically process word forms.

Impaired extraction and consolidation of morphological regularities in developmental dyslexia: A domain general deficit?

The current study examined whether adults with Developmental Dyslexia are impaired in learning linguistic regularities in a novel language, and whether this may be explained by a domain general deficit in the effect of sleep on consolidation. We compared online learning and offline consolidation of morphological regularities in individuals with Developmental Dyslexia (N = 40) and typical readers (N = 38). Participants learned to apply plural inflections to novel words based on morpho-phonological rules embedded in the input and learned to execute a finger motor sequence task. To test the effects of time and sleep on consolidation, participants were assigned into one of two sleep-schedule groups, trained in the evening or in the morning and tested 12 and 24 h later. Unlike typical readers, Dyslexic readers did not extract the morpho-phonological regularities during training and as a group they did not show offline gains in inflecting trained items 24 h after training, suggesting that the deficit in extraction of regularities during training may be related to the deficit in consolidation. The offline gains in dyslexic readers, were correlated with their prior phonological abilities, and were less affected by sleep than those of typical readers. Although no deficit was found in the consolidation of the motor task, dyslexic readers were again less successful in generating an abstract representation of the motor sequence, reflected in a difficulty to generalize the motor sequence knowledge acquired using one hand to the untrained hand. The results suggest that individuals with Developmental Dyslexia have a domain general deficit in extracting statistical regularities from an input. Within the language domain this deficit is reflected in reduced benefits of consolidation, particularly during sleep, perhaps due to reduced prior phonological abilities, which may impede the individual's ability to extract the linguistic regularities during and after training and thus constrain the consolidation process.

Font disfluency and reading performance in children: An event-related potential study

Expert adult readers process fluent and disfluent fonts differently, at both early perceptual and late higher-order processing stages. This finding has been interpreted as reflecting the more difficult to read disfluent fonts requiring greater neural resources. We aimed to investigate whether neural activity is affected by font disfluency in pre-adolescent readers, and to determine if neural responses are related to reading performance. Thirty-three participants between 8 and 12 years old completed two one-back tasks using letter and word stimuli, where font was manipulated (fluent versus disfluent stimuli), during which electroencephalography was recorded. Event related potentials (ERPs) were calculated relative to non-target stimuli for both tasks. The Woodcock Johnson III Tests of Achievement reading specific tests, and the Castles and Coltheart Test 2 were also collected. Font (fluent versus disfluent stimuli) did not consistently affect neural activity during both the letter and word tasks. Fluent stimuli elicited greater late activity (450-600 ms) than disfluent stimuli during the word task, suggesting easy-to-read fonts may enhance the maintenance of words in visual working memory and facilitate the retrieval of semantic information. However, reading performance was not associated with neural disfluency effects, suggesting that pre-adolescents are still at an early developmental reading period. Font manipulation may be a useful way to track developmental reading trajectories in the brain.

The Role of Neural and Genetic Processes in Learning to Read and Specific Reading Disabilities: Implications for Instruction

To learn to read, the brain must repurpose neural systems for oral language and visual processing to mediate written language. We begin with a description of computational models for how alphabetic written language is processed. Next, we explain the roles of a dorsal sublexical system in the brain that relates print and speech, a ventral lexical system that develops the visual expertise for rapid orthographic processing at the word level, and the role of cognitive control networks that regulate attentional processes as children read. We then use studies of children, adult illiterates learning to read, and studies of poor readers involved in intervention, to demonstrate the plasticity of these neural networks in development and in relation to instruction. We provide a brief overview of the rapid increase in the field's understanding and technology for assessing genetic influence on reading. Family studies of twins have shown that reading skills are heritable, and molecular genetic studies have identified numerous regions of the genome that may harbor candidate genes for the heritability of reading. In selected families, reading impairment has been associated with major genetic effects, despite individual gene contributions across the broader population that appear to be small. Neural and genetic studies do not prescribe how children should be taught to read, but these studies have underscored the critical role of early intervention and ongoing support. These studies also have highlighted how structured instruction that facilitates access to the sublexical components of words is a critical part of training the brain to read.

A Scoping Review on Movement, Neurobiology and Functional Deficits in Dyslexia: Suggestions for a Three-Fold Integrated Perspective

Developmental dyslexia is a common complex neurodevelopmental disorder. Many theories and models tried to explain its symptomatology and find ways to improve poor reading abilities. The aim of this scoping review is to summarize current findings and several approaches and theories, focusing on the interconnectedness between motion, emotion and cognition and their connection to dyslexia. Consequently, we present first a brief overview of the main theories and models regarding dyslexia and its proposed neural correlates, with a particular focus on cerebellar regions and their involvement in this disorder. After examining different types of intervention programs and remedial training, we highlight the effects of a specific structured sensorimotor intervention named Quadrato Motor Training (QMT). QMT utilizes several cognitive and motor functions known to be relevant in developmental dyslexia. We introduce its potential beneficial effects on reading skills, including working memory, coordination and attention. We sum its effects ranging from behavioral to functional, structural and neuroplastic, especially in relation to dyslexia. We report several recent studies that employed this training technique with dyslexic participants, discussing the specific features that distinguish it from other training within the specific framework of the Sphere Model of Consciousness. Finally, we advocate for a new perspective on developmental dyslexia integrating motion, emotion and cognition to fully encompass this complex disorder.

What's in a game: Video game visual-spatial demand location exhibits a double dissociation with reading speed

This research sought to clarify the nature of the relationship between video game experience, attention, and reading. Previous studies have suggested playing action video games can improve reading ability in children with dyslexia. Other research has linked video game experience with visual-spatial attention, and visual-spatial attention with reading. We hypothesized that the visual-spatial demands of video games may drive relationships with reading through attentional processing. In this experiment we used a hybrid attention/reading task to explore the relationship between video game visual-spatial demands, reading and attention. We also developed novel visual-spatial demand measures using participants' top five played video games for an individual-specific measure of visual demands. Peripheral visual demands in video games were associated with faster reading times, while central visual demands were associated with slower reading times for both phonetic decoding and lexical reading. In addition, video game experience in terms of hours spent playing video games each week interacted with the cueing effect size in the lexical reading condition, with experienced video game players exhibiting a larger cueing effect than participants with less video game experience. These results suggest that exposure to peripheral visual spatial demands in video games may be related to both lexical and sublexical reading processes in hybrid attentional reading tasks such as ours with skilled adult readers, which has implications not only for models of how ventral and dorsal stream reading and visual-spatial attention are integrated, but also for the development of dyslexia diagnostics and remediation.

Use of Virtual Reality in Children with Dyslexia

In recent years, the study of dyslexia has seen rapid progress in definition and classification, neuropsychological correlates, neurobiological factors, and intervention. However, there are few studies on how virtual reality can affect improving cognitive domains and cross-cutting pedagogical skills. We, therefore, tested intervention through the use of a virtual reality rehabilitation system (VRRS) in children with dyslexia. Twenty-eight patients diagnosed with dyslexia were enrolled in this study. One-half underwent conventional neuropsychological treatment, and the other half performed VR neurorehabilitation training using the VRRS. All patients were evaluated by neuropsychological assessment at baseline (T0) and at the end of the protocol (T1). The assessment included the administration of the Wechsler Intelligence Scale for Children-IV and the Italian Battery for the Assessment of Dyslexia and Dysorthography. Our results showed a significant difference in word-reading test scores as well as in homophonic writing. In addition, treatment type was found to affect some domains of the WISC. We believe that the VRRS led to improved outcomes through the use of VR, which encourages active exploration, improves engagement, and provides motivation and enjoyment, allowing longer training sessions and improving treatment adherence.

Researcher-practitioner partnerships and in-school laboratories facilitate translational research in reading

Educational neuroscience approaches have helped to elucidate the brain basis of Reading Disability (RD) and of reading intervention response; however, there is often limited translation of this knowledge to the broader scientific and educational communities. Moreover, this work is traditionally lab-based, and thus the underlying theories and research questions are siloed from classroom practices. With growing awareness of the neurobiological origins of RD and increasing popularity of putative "brain-based" approaches in clinics and classrooms, it is imperative that we create more direct and bidirectional communication between scientists and practitioners. Such direct collaborations can help dispel neuromyths, and lead to increased understanding of the promises and pitfalls of neuroscience approaches. Moreover, direct partnerships between researchers and practitioners can lead to greater ecological validity in study designs to improve upon the translational potential of findings. To this end, we have forged collaborative partnerships, and built cognitive neuroscience laboratories within independent reading disabilities schools. This approach affords frequent and ecologically valid neurobiological assessment as children's reading improves in response to intervention. It also permits the creation of dynamic models of leading and lagging relationships of students' learning, and identification of individual-level predictors of intervention response. The partnerships also provide in-depth knowledge of student characteristics and classroom practices, which, when combined with the data we acquire, may facilitate optimization of instructional approaches. In this commentary, we discuss the creation of our partnerships, the scientific problem we are addressing (variable response to reading intervention), and the epistemological significance of researcher-practitioner bi-directional learning.

Structural white matter characteristics for working memory and switching/inhibition in children with reading difficulties: The role of the left superior longitudinal fasciculus

Reading difficulties (RDs) are characterized by slow and inaccurate reading as well as additional challenges in cognitive control (i.e., executive functions, especially in working memory, inhibition, and visual attention). Despite evidence demonstrating differences in these readers' language and visual processing abilities, white matter differences associated with executive functions (EFs) difficulties in children with RDs are scarce. Structural correlates for reading and EFs in 8- to 12-year-old children with RDs versus typical readers (TRs) were examined using diffusion tensor imaging (DTI) data. Results suggest that children with RDs showed significantly lower reading and EF abilities versus TRs. Lower fractional anisotropy (FA) in left temporo-parietal tracts was found in children with RDs, who also showed positive correlations between reading and working memory and switching/inhibition scores and FA in the left superior longitudinal fasciculus (SLF). FA in the left SLF predicted working memory performance mediated by reading ability in children with RDs but not TRs. Our findings support alterations in white matter tracts related to working memory, switching/inhibition, and overall EF challenges in children with RDs and the linkage between working memory difficulties and FA alterations in the left SLF in children with RDs via reading.

Typical and Atypical Development of Visual Expertise for Print as Indexed by the Visual Word N1 (N170w): A Systematic Review

The visual word N1 (N170w) is an early brain ERP component that has been found to be a neurophysiological marker for print expertise, which is a prelexical requirement associated with reading development. To date, no other review has assimilated existing research on reading difficulties and atypical development of processes reflected in the N170w response. Hence, this systematic review synthesized results and evaluated neurophysiological and experimental procedures across different studies about visual print expertise in reading development. Literature databases were examined for relevant studies from 1995 to 2020 investigating the N170w response in individuals with or without reading disorders. To capture the development of the N170w related to reading, results were compared between three different age groups: pre-literate children, school-aged children, and young adults. The majority of available N170w studies (N = 69) investigated adults (n = 31) followed by children (school-aged: n = 21; pre-literate: n = 4) and adolescents (n = 1) while some studies investigated a combination of these age groups (n = 12). Most studies were conducted with German-speaking populations (n = 17), followed by English (n = 15) and Chinese (n = 14) speaking participants. The N170w was primarily investigated using a combination of words, pseudowords, and symbols (n = 20) and mostly used repetition-detection (n = 16) or lexical-decision tasks (n = 16). Different studies posed huge variability in selecting electrode sites for analysis; however, most focused on P7, P8, and O1 sites of the international 10–20 system. Most of the studies in adults have found a more negative N170w in controls than poor readers, whereas in children, the results have been mixed. In typical readers, N170w ranged from having a bilateral distribution to a left-hemispheric dominance throughout development, whereas in young, poor readers, the response was mainly right-lateralized and then remained in a bilateral distribution. Moreover, the N170w latency has varied according to age group, with adults having an earlier onset yet with shorter latency than school-aged and pre-literate children. This systematic review provides a comprehensive picture of the development of print expertise as indexed by the N170w across age groups and reading abilities and discusses theoretical and methodological differences and challenges in the field, aiming to guide future research.

Comparative research on neural dysfunction in children with dyslexia under different writing systems: A meta-analysis study

Developmental dyslexia is a special learning disorder which is prevalent in all languages. A central question in dyslexia is whether the neural mechanism of their defects is universal or distinct in different writing systems. Using meta-analytic approach, we created meta-images using activation abnormalities in Chinese and alphabetic children with dyslexia to find convergence and divergence under different writing systems. The results revealed that dyslexic children have a universal attention-related dysfunction with hypoactivation in the left inferior frontal cortex (IFC) and the anterior cingulate cortex (ACC) under different writing systems, in spite of differences of degree and spatial extent in those regions. Alphabetic dyslexic children additionally showed hypoactivation in the left occipito-temporo-parietal regions. Chinese dyslexic children showed specific hyperactivation in the right postcentral gyrus, the left rectus, and the right middle temporal gyrus. The present meta-analysis for the first time showed both shared and distinct abnormalities in children with dyslexia under Chinese and alphabetic writing systems.

Training second-grade dyslexic students using a computerized program in Asyut, Egypt

Background

Dyslexia is characterized by difficulties in spelling and reading. The aim of this study is to identify domains of cognitive strength and weakness of students with dyslexia and to study the effect of an especially designed computerized training program on their reading abilities. This study was conducted on 2nd-grade primary school students in Asyut city, Egypt (n = 560). Identification of students with dyslexia was done using Arabic Reading Achievement test and a newly constructed computerized Arabic Cognitive Abilities diagnostic battery for Reading (CADB-R). Training was applied using a newly constructed Computerized Cognitive abilities training battery for reading (CATB-R).

Results

The prevalence of dyslexia was 13.9% (N = 52/373), and it was higher among girls (15.8%) than boys (11.7%). After application of the training program, there was a significant increase in post-training mean scores of CADB-R score in their total and all sub-items.

Conclusions

All struggling readers should be included in well-tailored research-based rehabilitation programs.

Clinical trial registration Training Second-grade Dyslexic Students Using a Computerized Program in Assiut, Egypt (Dyslexia), NCT04642859, 12 November 2020. URL: https://register.clinicaltrials.gov/prs/app/action/Status?uid=U000495F&ts=10&sid=S000AD3G&cx=20acrp

Evidence of Altered Functional Connectivity at Rest in the Writing Network of Children with Dyslexia

Aim. Handwriting abilities in children with dyslexia (DYS) are not well documented in the current literature, and the presence of graphomotor impairment in addition to spelling impairment in dyslexia is controversial. Using resting-state functional connectivity (RSFC), the present study aims to answer the following question: are there markers of graphomotor impairment at rest in DYS children? Method. The participants were children with DYS and typically developing (TD) children (n = 32) from French-speaking primary schools (M_age = 9.3 years). The behavioural evaluation consisted of spelling and handwriting measures. Participants underwent a resting-state fMRI scan. Results. Analyses of RSFC focused on a brain region responsible for graphomotor processes—the graphemic/motor frontal area (GMFA). The RSFC between the GMFA and all other voxels of the brain was measured. Whole-brain ANOVAs were run to compare RSFC in DYS and TD children. The results demonstrated reduced RSFC in DYS compared to TD between the GMFA and brain areas involved in both spelling processes and motor-related processes. Conclusions. For the first time, this study highlighted a disruption of the writing network in DYS. By identifying functional markers of both spelling and handwriting deficits at rest in young DYS participants, this study supports the presence of graphomotor impairment in dyslexia.

Evidence from ERP and Eye Movements as Markers of Language Dysfunction in Dyslexia

Developmental dyslexia is a complex reading disorder involving genetic and environmental factors. After more than a century of research, its etiology remains debated. Two hypotheses are often put forward by scholars to account for the causes of dyslexia. The most common one, the linguistic hypothesis, postulates that dyslexia is due to poor phonological awareness. The alternative hypothesis considers that dyslexia is caused by visual-attentional deficits and abnormal eye movement patterns. This article reviews a series of selected event-related brain potential (ERP) and eye movement studies on the reading ability of dyslexic individuals to provide an informed state of knowledge on the etiology of dyslexia. Our purpose is to show that the two abovementioned hypotheses are not necessarily mutually exclusive, and that dyslexia should rather be considered as a multifactorial deficit.

How Learning to Read Changes the Listening Brain

Reading acquisition reorganizes existing brain networks for speech and visual processing to form novel audio-visual language representations. This requires substantial cortical plasticity that is reflected in changes in brain activation and functional as well as structural connectivity between brain areas. The extent to which a child's brain can accommodate these changes may underlie the high variability in reading outcome in both typical and dyslexic readers. In this review, we focus on reading-induced functional changes of the dorsal speech network in particular and discuss how its reciprocal interactions with the ventral reading network contributes to reading outcome. We discuss how the dynamic and intertwined development of both reading networks may be best captured by approaching reading from a skill learning perspective, using audio-visual learning paradigms and longitudinal designs to follow neuro-behavioral changes while children's reading skills unfold.

Using Neurofeedback to Restore Inter-Hemispheric Imbalance: A Study Protocol for Adults With Dyslexia

Neurofunctional models of developmental dyslexia (DD) point out disruption of the left-lateralized reading network. In individuals with DD, the left temporo-parietal (TP) regions are underactivated during reading tasks and a dysfunctional activation of the contralateral regions is reported. After a successful reading intervention, left TP lateralization was found to be increased in children with DD. Previous studies measured the effect of modulating the excitability of the left TP cortex using non-invasive brain stimulation (NIBS) in individuals with reading difficulties, showing significant reading improvements. NIBS exclusion criteria and safety guidelines may limit its application in settings without medical supervision and in younger populations. Neurofeedback (NF) training could be an alternative intervention method for modulating the inter-hemispheric balance of the temporal–parietal regions in DD. To date, the effect of NF on reading has been scarcely investigated. Few protocols increasing beta activity in underactivated areas showed improved reading outcomes. However, none of the previous studies designed the NF intervention based on a neurofunctional model of DD. We aim to propose a study protocol for testing the efficacy of a NF training specifically designed for inducing a functional hemispheric imbalance of the tempo-parietal regions in adults with DD. A randomized clinical trial aimed at comparing two experimental conditions is described: (a) Enhancing left beta/theta power ratio NF training in combination with reducing right beta/theta power ratio NF training and (b) sham NF training.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier [NCT04989088].

Theory-driven classification of reading difficulties from fMRI data using Bayesian latent-mixture models

Decades of research have led to several competing theories regarding the neural contributors to impaired reading. But how can we know which theory (or theories) identifies the types of markers that indeed differentiate between individuals with reading disabilities (RD) and their typically developing (TD) peers? To answer this question, we propose a new analytical tool for theory evaluation and comparison, grounded in the Bayesian latent-mixture modeling framework. We start by constructing a series of latent-mixture classification models, each reflecting one existing theoretical claim regarding the neurofunctional markers of RD (highlighting network-level differences in either mean activation, inter-subject heterogeneity, inter-region variability, or connectivity). Then, we run each model on fMRI data alone (i.e., while models are blind to participants' behavioral status), which enables us to interpret the fit between a model's classification of participants and their behavioral (known) RD/TD status as an estimate of its explanatory power. Results from n=127 adolescents and young adults (RD: n=59; TD: n=68) show that models based on network-level differences in mean activation and heterogeneity failed to differentiate between TD and RD individuals. In contrast, classifications based on variability and connectivity were significantly associated with participants' behavioral status. These findings suggest that differences in inter-region variability and connectivity may be better network-level markers of RD than mean activation or heterogeneity (at least in some populations and tasks). More broadly, the results demonstrate the promise of latent-mixture modeling as a theory-driven tool for evaluating different theoretical claims regarding neural contributors to language disorders and other cognitive traits.

Convergent and divergent brain structural and functional abnormalities associated with developmental dyslexia

Brain abnormalities in the reading network have been repeatedly reported in individuals with developmental dyslexia (DD); however, it is still not totally understood where the structural and functional abnormalities are consistent/inconsistent across languages. In the current multimodal meta-analysis, we found convergent structural and functional alterations in the left superior temporal gyrus across languages, suggesting a neural signature of DD. We found greater reduction in grey matter volume and brain activation in the left inferior frontal gyrus in morpho-syllabic languages (e.g. Chinese) than in alphabetic languages, and greater reduction in brain activation in the left middle temporal gyrus and fusiform gyrus in alphabetic languages than in morpho-syllabic languages. These language differences are explained as consequences of being DD while learning a specific language. In addition, we also found brain regions that showed increased grey matter volume and brain activation, presumably suggesting compensations and brain regions that showed inconsistent alterations in brain structure and function. Our study provides important insights about the etiology of DD from a cross-linguistic perspective with considerations of consistency/inconsistency between structural and functional alterations.

Resting-state functional connectivity and reading subskills in children

Individual differences in reading ability have been linked to characteristics of functional connectivity in the brain in both children and adults. However, many previous studies have used single or composite measures of reading, leading to difficulty characterizing the role of functional connectivity in discrete subskills of reading. The present study addresses this issue using resting-state fMRI to examine how resting-state functional connectivity (RSFC) related to individual differences in children's reading subskills, including decoding, sight word reading, reading comprehension, and rapid automatized naming (RAN). Findings showed both positive and negative RSFC-behaviour relationships that diverged across different reading subskills. Positive relationships included increasing RSFC among left dorsal and anterior regions with increasing decoding proficiency, and increasing RSFC between the left thalamus and right fusiform gyrus with increasing sight word reading, RAN, and reading comprehension abilities. In contrast, negative relationships suggested greater functional segregation of attentional and reading networks with improved performance on RAN, decoding, and reading comprehension tasks. Importantly, the results suggest that although reading subskills rely to some extent on shared functional networks, there are also distinct functional connections supporting different components of reading ability in children.

Poor reading is characterized by a more connected network with wrong hubs

Using graph theory, we examined topological organization of the language network in Chinese children with poor reading during an auditory rhyming task and a visual spelling task, compared to reading-matched controls and age-matched controls. First, poor readers (PR) showed reduced clustering coefficient in the left inferior frontal gyrus (IFG) and higher nodal efficiency in the bilateral superior temporal gyri (STG) during the visual task, indicating a less functionally specialized cluster around the left IFG and stronger functional links between bilateral STGs and other regions. Furthermore, PR adopted additional right-hemispheric hubs in both tasks, which may explain increased global efficiency across both tasks and lower normalized characteristic shortest path length in the visual task for the PR. These results underscore deficits in the left IFG during visual word processing and conform previous findings about compensation in the right hemisphere in children with poor reading.

Neural correlates of cognitive control deficits in children with reading disorder

Reading disorder (RD) is characterized by deficient phonological processing, but children with RD also have cognitive control deficits, the neural correlates of which are not fully understood. We used fMRI to assess neural activity during the resolution of cognitive conflict on the Simon Spatial Incompatibility task and patterns of resting-state functional connectivity (RSFC) from task control (TC) regions in 7-12-year-old children with RD compared to their typically developing (TD) peers. Relative to TD children (n = 17), those with RD (n = 16) over-engaged a right superior/medial frontal cluster during the resolution of conflict (p = .05). Relative to TD children (n = 18), those with RD (n = 17) also showed reduced RSFC (voxel-wise p < .001; cluster-size p < .05, FDR corrected) from cingulo-opercular seeds to left hemisphere fronto-parietal and temporo-parietal reading-related regions, perhaps reflecting reduced organization of TC circuits and reduced integration with reading-related regions. Children with RD additionally showed reduced RSFC between fronto-parietal and default mode network regions. Follow-up analyses in a subset of children with both useable task and resting state data (RD = 13; TD = 17) revealed that greater conflict-related activation of the right frontal Simon task ROI associated with better word-reading, perhaps suggesting a compensatory role for this over-engagement. Connectivity from fronto-parietal seeds significantly associated with Simon task performance and word-reading accuracy in RD children. These findings suggest that altered functioning and connectivity of control circuits may contribute to cognitive control deficits in children with RD. Future studies should assess the utility of adding cognitive control training to reading remediation programs.

Neural underpinnings of dyslexia as a disorder of visuo‐spatial attention

For nearly 100 years, the underlying cause of dyslexia has been a matter of much debate, with widely varying viewpoints that have ranged from considering dyslexia as largely a learning disability to claims that it is essentially a perceptual defect occurring early along the visual pathway. This paper reviews some of this literature with particular reference to the studies that have implicated a defect in the afferent visual pathways in the aetiology of the disorder, then goes on to outline a neural theory of how functionally distinct parallel pathways in vision interact with each other in the process of reading and suggests how a defect in these pathways can lead to reading difficulties. Central to the proposed scheme is the suggestion that a fast-track pathway, arising from the magnocellular cells in the retina and acting through an attentional mechanism, has a gating function in spotlighting the individual letters of a text in a sequential fashion. That such gating occurs at the level of the primary visual cortex is supported by recent physiological evidence concerning attentional mechanisms.

Intracranial recording in patients with aphasia using nanomaterial-based flexible electronics: promises and challenges

In recent years, researchers have studied how nanotechnology could enhance neuroimaging techniques. The application of nanomaterial-based flexible electronics has the potential to advance conventional intracranial electroencephalography (iEEG) by utilising brain-compatible soft nanomaterials. The resultant technique has significantly high spatial and temporal resolution, both of which enhance the localisation of brain functions and the mapping of dynamic language processing. This review presents findings on aphasia, an impairment in language and communication, and discusses how different brain imaging techniques, including positron emission tomography, magnetic resonance imaging, and iEEG, have advanced our understanding of the neural networks underlying language and reading processing. We then outline the strengths and weaknesses of iEEG in studying human cognition and the development of intracranial recordings that use brain-compatible flexible electrodes. We close by discussing the potential advantages and challenges of future investigations adopting nanomaterial-based flexible electronics for intracranial recording in patients with aphasia.

Altered electroencephalographic networks in developmental dyslexia after remedial training: a prospective case-control study

Electroencephalographic studies using graph theoretic analysis have found aberrations in functional connectivity in children with developmental dyslexia. However, how the training with visual tasks can change the functional connectivity of the semantic network in developmental dyslexia is still unclear. We looked for differences in local and global topological properties of functional networks between 21 healthy controls and 22 dyslexic children (8-9 years old) before and after training with visual tasks in this prospective case-control study. The minimum spanning tree method was used to construct the subjects' brain networks in multiple electroencephalographic frequency ranges during a visual word/pseudoword discrimination task. We found group differences in the theta, alpha, beta and gamma bands for four graph measures suggesting a more integrated network topology in dyslexics before the training compared to controls. After training, the network topology of dyslexic children had become more segregated and similar to that of the controls. In the θ, α and β1-frequency bands, compared to the controls, the pre-training dyslexics exhibited a reduced degree and betweenness centrality of the left anterior temporal and parietal regions. The simultaneous appearance in the left hemisphere of hubs in temporal and parietal (α, β1), temporal and superior frontal cortex (θ, α), parietal and occipitotemporal cortices (β1), identified in the networks of normally developing children was not present in the brain networks of dyslexics. After training, the hub distribution for dyslexics in the theta and beta1 bands had become similar to that of the controls. In summary, our findings point to a less efficient network configuration in dyslexics compared to a more optimal global organization in the controls. This is the first study to investigate the topological organization of functional brain networks of Bulgarian dyslexic children. Approval for the study was obtained from the Ethics Committee of the Institute of Neurobiology and the Institute for Population and Human Studies, Bulgarian Academy of Sciences (approval No. 02-41/12.07.2019) on March 28, 2017, and the State Logopedic Center and the Ministry of Education and Science (approval No. 09-69/14.03.2017) on July 12, 2019.

Quantitative EEG in Childhood Attention Deficit Hyperactivity Disorder and Learning Disabilities

The clinical use of the quantitative EEG (QEEG) from the pioneering work of John has received a new impetus thanks to new neuroimaging techniques and the possibility of using a number of normative databases both of normal subjects and of subjects with definite pathologies. In this direction, the term personalized medicine is becoming more and more common, a medical procedure that separates patients into different groups based on their predicted response to the quantitative EEG. This has allowed the study of single subjects and to customize health care, with decisions and treatments tailored to each individual patient, as well as improvement of knowledge of the pathophysiological mechanisms of specific diseases. This review article will present the most recent evidence in the field of developmental neuropsychiatric disorders obtained from the application of quantitative EEG both in clinical group studies (attention deficit hyperactivity disorder, developmental dyslexia, oppositional defiant disorder) and in individual case studies not yet published.

Functional connectivity in the developing language network in 4-year-old children predicts future reading ability

Understanding how pre-literate children's language abilities and neural function relate to future reading ability is important for identifying children who may be at-risk for reading problems. Pre-literate children are already proficient users of spoken language and their developing brain networks for language become highly overlapping with brain networks that emerge during literacy acquisition. In the present longitudinal study, we examined language abilities, and neural activation and connectivity within the language network in pre-literate children (mean age = 4.2 years). We tested how language abilities, brain activation, and connectivity predict children's reading abilities 1 year later (mean age = 5.2 years). At Time 1, children (n = 37) participated in a functional near infrared spectroscopy (fNIRS) experiment of speech processing (listening to words and pseudowords) and completed a standardized battery of language and cognitive assessments. At Time 2, children (n = 28) completed standardized reading assessments. Using psychophysiological interaction (PPI) analyses, we observed significant connectivity between the left IFG and right STG in pre-literate children, which was modulated by task (i.e., listening to words). Neural activation in left IFG and STG and increased task-modulated connectivity between the left IFG and right STG was predictive of multiple reading outcomes. Increased connectivity was associated later with increased reading ability.

Cortical responses to letters and ambiguous speech vary with reading skills in dyslexic and typically reading children

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Text recalibrates ambiguous speech perception in children with and without dyslexia.

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Dyslexia and poorer reading skills are linked to reduced left fusiform activation.

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Poorer letter-speech sound matching is linked to higher superior temporal activation.

One of the proposed issues underlying reading difficulties in dyslexia is insufficiently automatized letter-speech sound associations. In the current fMRI experiment, we employ text-based recalibration to investigate letter-speech sound mappings in 8–10 year-old children with and without dyslexia. Here an ambiguous speech sound /a?a/ midway between /aba/ and /ada/ is combined with disambiguating “aba” or “ada” text causing a perceptual shift of the ambiguous /a?a/ sound towards the text (recalibration). This perceptual shift has been found to be reduced in adults but not in children with dyslexia compared to typical readers. Our fMRI results show significantly reduced activation in the left fusiform in dyslexic compared to typical readers, despite comparable behavioural performance. Furthermore, enhanced audio-visual activation within this region was linked to better reading and phonological skills. In contrast, higher activation in bilateral superior temporal cortex was associated with lower letter-speech sound identification fluency. These findings reflect individual differences during the early stages of reading development with reduced recruitment of the left fusiform in dyslexic readers together with an increased involvement of the superior temporal cortex in children with less automatized letter-speech sound associations.

A hierarchical deficit model of reading disability: Evidence from dynamic causal modelling analysis

Deficits have been documented in visuo-orthographic processing as well as phonological retrieval/manipulation during visual word reading in individuals with reading disability (RD); however, the relationship between these deficits remains unclear. Previously, we found that during word reading, visuo-orthographic deficit appears to be a neural signature of RD, but deficits in phonological retrieval/manipulation appears to be a consequence of being RD (Cao et al., 2020). Therefore, in the current study, we directly tested the hypothesis that during visual word reading, deficit in phonological retrieval/manipulation may result from weakened input from visuo-orthographic regions, and that this relationship tends to be universal across languages. We conducted a dynamic causal modelling analysis of fMRI data from Chinese-English bilingual children (9-11 years, N = 78) with or without RD during a visual word rhyming judgment task. We found a weaker connection from the left inferior temporal gyrus (ITG) to the left dorsal inferior frontal gyrus (dIFG) in children with RD and reading controls than the connection found in age controls for both Chinese and English. This finding suggests that the phonological deficit at the dIFG may result from weak input from the visuo-orthographic region and this connection appears to be responsive to reading level rather than RD, because the reading-control children were similar to children with RD. We also found that the left ITG was selectively connected with language-specific regions (i.e., the left inferior parietal lobe (IPL) for Chinese and the left ventral inferior frontal gyrus (vIFG) for English) depending on the language being processed; however, this language selectivity was reduced in children with RD, suggesting that decreased language specialization is associated with RD. Using a double control design, our study suggests that during reading, the visuo-orthographic deficit of RD constrains the development of the connection from orthography to phonology and to other language-specific processing due to distorted quantity and quality of reading.

The development of brain functional connectome during text reading

Reading is an important skill for human beings to obtain information, whose acquisition is a major learning task for children. Especially, compared with single word reading, text reading requires an integration of multiple cognitive processes, which makes its underlying neural developmental mechanism not only extremely complicated but also remained poorly understood. Employing the graph theory analysis method, the present study explored the development of brain in the context of story reading from the perspective of connectomics. Forty-two primary school students and thirty-two adults read the stories in the functional magnetic resonance imaging (fMRI) experiment. We found that compared with children, adults had increased connectivity strength, nodal degree, and modular interactions for vision-related and semantics-related brain regions while decreased connectivity strength, nodal degree, and modular interactions for phonology-related brain regions. Brain-behavior association analysis suggested that the transmission to vision-related brain circuits would enhance the reading performance in adults, whereas phonology-related brain circuits played important roles in children’s reading before they develop into fluent readers. Collectivity, we highlight a shift from reliance on phonology-related networks to semantics-related and vision-related networks with age for text reading, which provides insights into the underlying neural signature of developmental cognitive mechanisms.

Comorbidity Between Math and Reading Problems: Is Phonological Processing a Mutual Factor?

There is a relationship between reading and math skills, as well as comorbidity between reading and math disorders. A mutual foundation for this comorbidity could be that the quality of phonological representations is important for both early reading and arithmetic. In this study, we examine this hypothesis in a sample traced longitudinally from preschool to first grade (N = 259). The results show that phonological awareness does not explain development in arithmetic, but that there is an indirect effect between phoneme awareness in preschool and arithmetic in first grade via phoneme awareness in first grade. This effect is, however, weak and restricted to verbal arithmetic and not arithmetic fluency. This finding is only partly in line with other studies, and a reason could be that this study more strongly controls for confounders and previous skills than other studies.

Dyslexia detection using 3D convolutional neural networks and functional magnetic resonance imaging

BACKGROUND AND OBJECTIVES

Dyslexia is a disorder of neurological origin which affects the learning of those who suffer from it, mainly children, and causes difficulty in reading and writing. When undiagnosed, dyslexia leads to intimidation and frustration of the affected children and also of their family circles. In case no early intervention is given, children may reach high school with serious achievement gaps. Hence, early detection and intervention services for dyslexic students are highly important and recommended in order to support children in developing a positive self-esteem and reaching their maximum academic capacities. This paper presents a new approach for automatic recognition of children with dyslexia using functional magnetic resonance Imaging.

METHODS

Our proposed system is composed of a sequence of preprocessing steps to retrieve the brain activation areas during three different reading tasks. Conversion to Nifti volumes, adjustment of head motion, normalization and smoothing transformations were performed on the fMRI scans in order to bring all the subject brains into one single model which will enable voxels comparison between each subject. Subsequently, using Statistical Parametric Maps (SPMs), a total of 165 3D volumes containing brain activation of 55 children were created. The classification of these volumes was handled using three parallel 3D Convolutional Neural Network (3D CNN), each corresponding to a brain activation during one reading task, and concatenated in the last two dense layers, forming a single architecture devoted to performing optimized detection of dyslexic brain activation. Additionally, we used 4-fold cross validation method in order to assess the generalizability of our model and control overfitting.

RESULTS

Our approach has achieved an overall average classification accuracy of 72.73%, sensitivity of 75%, specificity of 71.43%, precision of 60% and an F1-score of 67% in dyslexia detection.

CONCLUSIONS

The proposed system has demonstrated that the recognition of dyslexic children is feasible using deep learning and functional magnetic resonance Imaging when performing phonological and orthographic reading tasks.

Learning difficulties in Japanese schoolchildren with focal epilepsy

BACKGROUND

Children with epilepsy often show some degree of cognitive impairment. In this study, we investigated their learning skills to clarify the characteristics of the difficulties related to learning in Japanese-speaking children with focal epilepsy.

METHODS

The study included 13 boys and 17 girls of mean age 9.7 years (standard deviation 2.61; range 6-14 years) with focal epilepsy and a normal magnetic resonance brain scan. None of the patients had any other neurological disorder.

RESULTS

Twenty-two children had "learning difficulties", i.e., an intellectual disability or low scores on a learning abilities task. Significant differences were found in age (P = 0.030), age at onset of epilepsy (P = 0.033), and electroencephalographic findings, as well as between bilateral vs. unilateral (P = 0.028) and right-localized vs. left-localized or bilateral (P = 0.014) involvement between subjects with and without learning difficulties. Seven (88%) of eight children with low scores on a learning abilities task showed abnormalities in reading speed.

DISCUSSION

More than half of Japanese-speaking children with focal epilepsy need learning assistance. This finding points to a need for learning support in children with focal epilepsy regardless of language. Measurement of reading speed is useful in children with learning difficulties to identify those who require early intervention.

Functional parcellation of the right cerebellar lobule VI in children with normal or impaired reading

Neuroimaging studies have reported that the right cerebellar lobule VI is engaged in reading, but its role is unclear. The goal of our study was to identify functionally-dissociable subregions in the right lobule VI and how these subregions contribute to reading in children with normal or impaired reading. In Experiment I, typically developing children performed an orthographic task and a phonological task during functional magnetic resonance imaging (fMRI). We classified the voxels in the right lobule VI into seven zones based on the patterns of functional connectivity with the cerebrum across both tasks. In Experiment II, we compared the brain activation and cerebro-cerebellar connectivities of each subregion between children readers with different reading levels. We did not find significant group differences in cerebellar activation. However, we found that impaired readers had considerably higher functional connectivity between R1 and the right angular gyrus and the right precuneus compared to the control group in the phonological task. These findings show that the right cerebellar lobule VI is functionally parceled and its subregions might be differentially connected with the cerebrum between children with normal reading abilities and those with impaired reading.

Development of Print-Speech Integration in the Brain of Beginning Readers With Varying Reading Skills

Learning print-speech sound correspondences is a crucial step at the beginning of reading acquisition and often impaired in children with developmental dyslexia. Despite increasing insight into audiovisual language processing, it remains largely unclear how integration of print and speech develops at the neural level during initial learning in the first years of schooling. To investigate this development, 32 healthy, German-speaking children at varying risk for developmental dyslexia (17 typical readers and 15 poor readers) participated in a longitudinal study including behavioral and fMRI measurements in first (T1) and second (T2) grade. We used an implicit audiovisual (AV) non-word target detection task aimed at characterizing differential activation to congruent (AVc) and incongruent (AVi) audiovisual non-word pairs. While children’s brain activation did not differ between AVc and AVi pairs in first grade, an incongruency effect (AVi > AVc) emerged in bilateral inferior temporal and superior frontal gyri in second grade. Of note, pseudoword reading performance improvements with time were associated with the development of the congruency effect (AVc > AVi) in the left posterior superior temporal gyrus (STG) from first to second grade. Finally, functional connectivity analyses indicated divergent development and reading expertise dependent coupling from the left occipito-temporal and superior temporal cortex to regions of the default mode (precuneus) and fronto-temporal language networks. Our results suggest that audiovisual integration areas as well as their functional coupling to other language areas and areas of the default mode network show a different development in poor vs. typical readers at varying familial risk for dyslexia.

Misunderstandings about developmental dyslexia: a historical overview

Developmental dyslexia is a reading disorder unrelated to intellectual disability, inadequate teaching systems or poor motivation for schooling. The first attempts to understand such difficulty of learning to read, connected the problem to a primary 'visual defect'. Since then, several models have been developed. In the last decades, autopsy and histopathological studies on the brain of developmental dyslexics provided neuroanatomical evidence of structural and morphological differences between the normal and dyslexic brains. Furthermore, neuroimaging studies allowed to understand the neural systems of reading and dyslexia. According to more recent studies, developmental dyslexia appears as a language-related neurodevelopmental disorder with a deficit in phonological decoding and visuospatial organization of the language code. Therefore, dyslexia is viewed as a multicomponential and complex disorder. Consequently, rehabilitation should be aimed at both the recovery of linguistic decoding processes and the improvement of visuo-spatial and attentional processes. This brief overview should be a valuable tool for a deeper understanding of dyslexic disorder. Literature searches in Medline, PsycINFO, EMBASE, Scopus, PubMed, Web of Science identified one hundred articles focusing attention on how this disorder has been considered over the years.

Men and women differ in the neural basis of handwriting

There is an ongoing debate about whether, and to what extent, males differ from females in their language skills. In the case of handwriting, a composite language skill involving language and motor processes, behavioral observations consistently show robust sex differences but the mechanisms underlying the effect are unclear. Using functional magnetic resonance imaging (fMRI) in a copying task, the present study examined the neural basis of sex differences in handwriting in 53 healthy adults (ages 19–28, 27 males). Compared to females, males showed increased activation in the left posterior middle frontal gyrus (Exner's area), a region thought to support the conversion between orthographic and graphomotor codes. Functional connectivity between Exner's area and the right cerebellum was greater in males than in females. Furthermore, sex differences in brain activity related to handwriting were independent of language material. This study identifies a novel neural signature of sex differences in a hallmark of human behavior, and highlights the importance of considering sex as a factor in scientific research and clinical applications involving handwriting.

Whole-Brain Functional Networks for Phonological and Orthographic Processing in Chinese Good and Poor Readers

The neural basis of dyslexia in different languages remains unresolved, and it is unclear whether the phonological deficit as the core deficit of dyslexia is language-specific or universal. The current functional magnetic resonance imaging (fMRI) study using whole-brain data-driven network analyses investigated the neural mechanisms for phonological and orthographic processing in Chinese children with good and poor reading ability. Sixteen good readers and 16 poor readers were requested to make homophone judgments (phonological processing) and component judgments (visual-orthographic processing) of presented Chinese characters. Poor readers displayed worse performance than the good readers in phonological processing, but not in orthographic processing. Whole-brain activation analyses showed compensatory activations in the poor readers during phonological processing and automatic phonological production activation in the good readers during orthographic processing. Significant group differences in the topological properties of their brain networks were found only in orthographic processing. Analyses of nodal degree centrality and betweenness centrality revealed significant group differences in both phonological and orthographic processing. The present study supports the phonological core deficit hypothesis of reading difficulty in Chinese. It also suggests that Chinese good and poor readers might recruit different strategies and neural mechanisms for orthographic processing.

Reading Outcomes for Individuals With Histories of Suspected Childhood Apraxia of Speech

Purpose The primary aims of this study were to examine the speech-language correlates of decoding difficulties in children with histories of suspected childhood apraxia of speech (sCAS) and to identify predictors of low-proficiency reading levels. Method Participants were school-age children and adolescents, 7-18 years of age, diagnosed with sCAS (n = 40) or speech sound disorder but no sCAS (SSD-no sCAS; n = 119). The sCAS and SSD-no sCAS reading groups were compared on measures of performance IQ, oral language, phonological awareness, rapid automatic naming, diadochokinetic rates, single word articulation, and multisyllable and nonsense word repetition. Logistic regression analyses were employed to identify predictors of low-proficiency reading in the sCAS and SSD-no sCAS groups. Results Sixty-five percent of the participants with sCAS compared to 24% of those with SSD-no sCAS were classified as low-proficiency readers based on nonsense and single word decoding. Analysis failed to reveal significant differences in reading, oral language, or phonological awareness between low-proficiency readers with sCAS and low-proficiency readers with SSD-no sCAS. Oral language and phonological awareness skills were the best predictors of reading level for all participants, followed by performance on multisyllabic word repetition and diadochokinetic rate. Conclusions The language and phonological awareness deficits of children with sCAS are related to their risks for reading failure. To a lesser degree, motor speech deficits and speech sound production also increase risks for reading difficulties. The findings justify early intervention for this subset of children.

Semantic and lexical features of words dissimilarly affected by non-fluent, logopenic, and semantic primary progressive aphasia

OBJECTIVE

To determine the effect of three psycholinguistic variables-lexical frequency, age of acquisition (AoA), and neighborhood density (ND)-on lexical-semantic processing in individuals with non-fluent (nfvPPA), logopenic (lvPPA), and semantic primary progressive aphasia (svPPA). Identifying the scope and independence of these features can provide valuable information about the organization of words in our mind and brain.

METHOD

We administered a lexical decision task-with words carefully selected to permit distinguishing lexical frequency, AoA, and orthographic ND effects-to 41 individuals with PPA (13 nfvPPA, 14 lvPPA, 14 svPPA) and 25 controls.

RESULTS

Of the psycholinguistic variables studied, lexical frequency had the largest influence on lexical-semantic processing, but AoA and ND also played an independent role. The results reflect a brain-language relationship with different proportional effects of frequency, AoA, and ND in the PPA variants, in a pattern that is consistent with the organization of the mental lexicon. Individuals with nfvPPA and lvPPA experienced an ND effect consistent with the role of inferior frontal and temporoparietal regions in lexical analysis and word form processing. By contrast, individuals with svPPA experienced an AoA effect consistent with the role of the anterior temporal lobe in semantic processing.

CONCLUSIONS

The findings are in line with a hierarchical mental lexicon structure with a conceptual (semantic) and a lexeme (word-form) level, such that a selective deficit at one of these levels of the mental lexicon manifests differently in lexical-semantic processing performance, consistent with the affected language-specific brain region in each PPA variant.

Reading Acquisition in Children: Developmental Processes and Dyslexia-Specific Effects

OBJECTIVE

Decreased activation to print in the left ventral, dorsal, and anterior pathways has been implicated in readers with dyslexia (DRs) but also is characteristic for typical beginning readers. Because most studies have compared DRs with their age-matched peers, the observed results could represent a dyslexia phenotype or a developmental delay. This study aimed to disentangle reading and dyslexia effects using 2 control groups matched for age and skill and a longitudinal design.

METHOD

Brain response for print was compared in DRs and typical readers (TRs) who, at the beginning of schooling (time point 1 [TP]; 6-7 years old), read on average 3 words per minute, as did DRs at TP1, but improved their reading to an average level, and advanced readers (ARs) who at TP1 read as well as DRs 2 years later (TP3; 8-9 years old). The TR and DR groups were tracked longitudinally to observe neurodevelopmental changes.

RESULTS

At TP1, DRs did not differ from TRs. Over time, only TRs developed a neural circuit for reading in the left inferior frontal and fusiform gyri. At TP3, DRs exhibited hypo-activation in these areas compared with age-matched (TRs at TP3) and reading-matched (ARs at TP1) controls. At TP3, TRs showed hypo-activation in the left frontal and bilateral ventral occipital regions compared with ARs, but these effects were nonoverlapping with DR hypo-activations and are partly explained by IQ.

CONCLUSION

Decreased activation of the left fusiform and inferior frontal gyri to print in DRs results from an atypical developmental trajectory of reading and cannot be explained solely by lower reading skills.

Altered Functional Connectivity of the Executive Functions Network During a Stroop Task in Children with Reading Difficulties

Children with reading difficulties (RDs) often receive related accommodations in schools, such as additional time for examinations and reading aloud written material. Existing data suggest that these readers share challenges in executive functions (EFs). Our study was designed to determine whether children with RDs have specific challenges in EFs and define neurobiological signatures for such difficulties using magnetic resonance imaging (MRI) data. Reading and EFs abilities were assessed in 8-12-year-old children with RDs and age-matched typical readers. Functional MRI data were acquired during a Stroop task, and functional connectivity of the EFs defined network was calculated in both groups and related to reading ability. Children with RDs showed lower reading and EFs abilities and demonstrated greater functional connectivity between the EFs network and visual, language, and cognitive control regions during the Stroop task, compared to typical readers. Our results suggest that children with RDs utilize neural circuits supporting EFs more so than do typical readers to perform a cognitive task. These results also provide a neurobiological explanation for the challenges in EFs shared by children with RDs and explain challenges this group shares outside of the reading domain.