RESUMO
The language network of the human brain has core components in the inferior frontal cortex and superior/middle temporal cortex, with left-hemisphere dominance in most people. Functional specialization and interconnectivity of these neocortical regions is likely to be reflected in their molecular and cellular profiles. Excitatory connections between cortical regions arise and innervate according to layer-specific patterns. Here, we generated a gene expression dataset from human postmortem cortical tissue samples from core language network regions, using spatial transcriptomics to discriminate gene expression across cortical layers. Integration of these data with existing single-cell expression data identified 56 genes that showed differences in laminar expression profiles between the frontal and temporal language cortex together with upregulation in layer II/III and/or layer V/VI excitatory neurons. Based on data from large-scale genome-wide screening in the population, DNA variants within these 56 genes showed set-level associations with interindividual variation in structural connectivity between the left-hemisphere frontal and temporal language cortex, and with the brain-related disorders dyslexia and schizophrenia which often involve affected language. These findings identify region-specific patterns of laminar gene expression as a feature of the brain's language network.
Assuntos
Idioma , Neocórtex , Humanos , Neocórtex/metabolismo , Lobo Temporal/metabolismo , Masculino , Feminino , Esquizofrenia/genética , Esquizofrenia/metabolismo , Neurônios/metabolismo , Lobo Frontal/metabolismo , Transcriptoma , AdultoRESUMO
Reading acquisition involves the integration of auditory and visual stimuli. Thus, low-level audiovisual multisensory integration might contribute to disrupted reading in developmental dyslexia. Although dyslexia is more frequently diagnosed in males and emerging evidence indicates that the neural basis of dyslexia might differ between sexes, previous studies examining multisensory integration did not evaluate potential sex differences nor tested its neural correlates. In the current study on 88 adolescents and young adults, we found that only males with dyslexia showed a deficit in multisensory integration of simple nonlinguistic stimuli. At the neural level, both females and males with dyslexia presented smaller differences in response to multisensory compared to those in response to unisensory conditions in the N1 and N2 components (early components of event-related potentials associated with sensory processing) than the control group. Additionally, in a subsample of 80 participants matched for nonverbal IQ, only males with dyslexia exhibited smaller differences in the left hemisphere in response to multisensory compared to those in response to unisensory conditions in the N1 component. Our study indicates that deficits of multisensory integration seem to be more severe in males than females with dyslexia. This provides important insights into sex-modulated cognitive processes that might confer vulnerability to reading difficulties.
Assuntos
Percepção Auditiva , Dislexia , Adolescente , Adulto Jovem , Humanos , Masculino , Feminino , Percepção Auditiva/fisiologia , Tempo de Reação/fisiologia , Percepção Visual/fisiologia , Caracteres Sexuais , Estimulação AcústicaRESUMO
Lesions in the language-dominant ventral occipitotemporal cortex (vOTC) can result in selective impairment of either reading or naming, resulting in alexia or anomia. Yet, functional imaging studies that show differential activation for naming and reading do not reveal activity exclusively tuned to one of these inputs. To resolve this dissonance in the functional architecture of the vOTC, we used focused stimulation to the vOTC in 49 adult patients during reading and naming, and generated a population-level, probabilistic map to evaluate if reading and naming are clearly dissociable within individuals. Language mapping (50â Hz, 2829 stimulations) was performed during passage reading (216 positive sites) and visual naming (304 positive sites). Within the vOTC, we isolated sites that selectively disrupted reading (24 sites in 11 patients) or naming (27 sites in 12 patients), and those that disrupted both processes (75 sites in 21 patients). The anteromedial vOTC had a higher probability of producing naming disruption, while posterolateral regions resulted in greater reading-specific disruption. Between them lay a multi-modal region where stimulation disrupted both reading and naming. This work provides a comprehensive view of vOTC organization-the existence of a heteromodal cortex critical to both reading and naming, along with a causally dissociable unimodal naming cortex, and a reading-specific visual word form area in the vOTC. Their distinct roles as associative regions may thus relate to their connectivity within the broader language network that is disrupted by stimulation, more than to highly selective tuning properties. Our work also implies that pre-surgical mapping of both reading and naming is essential for patients requiring vOTC resections, as these functions are not co-localized, and such mapping may prevent the occurrence of unexpected deficits.
Assuntos
Mapeamento Encefálico , Lobo Occipital , Leitura , Lobo Temporal , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Lobo Occipital/diagnóstico por imagem , Lobo Occipital/fisiopatologia , Adulto , Lobo Temporal/fisiopatologia , Lobo Temporal/diagnóstico por imagem , Mapeamento Encefálico/métodos , Idoso , Imageamento por Ressonância Magnética , Adulto Jovem , Idioma , Estimulação Luminosa/métodosRESUMO
The Simple View of Reading model suggests that intact language processing and word decoding lead to proficient reading comprehension, with recent studies pointing at executive functions as an important component contributing to reading proficiency. Here, we aimed to determine the underlying mechanism(s) for these changes. Participants include 120 8- to 12-year-old children (n = 55 with dyslexia, n = 65 typical readers) trained on an executive functions-based reading program, including pre/postfunctional MRI and behavioral data collection. Across groups, improved word reading was related to stronger functional connections within executive functions and sensory networks. In children with dyslexia, faster and more accurate word reading was related to stronger functional connections within and between sensory networks. These results suggest greater synchronization of brain systems after the intervention, consistent with the "neural noise" hypothesis in children with dyslexia and support the consideration of including executive functions as part of the Simple View of Reading model.
Assuntos
Dislexia , Função Executiva , Imageamento por Ressonância Magnética , Leitura , Humanos , Criança , Dislexia/fisiopatologia , Dislexia/psicologia , Dislexia/diagnóstico por imagem , Função Executiva/fisiologia , Masculino , Feminino , Encéfalo/fisiopatologia , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologiaRESUMO
Reading skills and developmental dyslexia, characterized by difficulties in developing reading skills, have been associated with brain anomalies within the language network. Genetic factors contribute to developmental dyslexia risk, but the mechanisms by which these genes influence reading skills remain unclear. In this preregistered study (https://osf.io/7sehx), we explored if developmental dyslexia susceptibility genes DNAAF4, DCDC2, NRSN1, and KIAA0319 are associated with brain function in fluently reading adolescents and young adults. Functional MRI and task performance data were collected during tasks involving written and spoken sentence processing, and DNA sequence variants of developmental dyslexia susceptibility genes previously associated with brain structure anomalies were genotyped. The results revealed that variation in DNAAF4, DCDC2, and NRSN1 is associated with brain activity in key language regions: the left inferior frontal gyrus, middle temporal gyrus, and intraparietal sulcus. Furthermore, NRSN1 was associated with task performance, but KIAA0319 did not yield any significant associations. Our findings suggest that individuals with a genetic predisposition to developmental dyslexia may partly employ compensatory neural and behavioral mechanisms to maintain typical task performance. Our study highlights the relevance of these developmental dyslexia susceptibility genes in language-related brain function, even in individuals without developmental dyslexia, providing valuable insights into the genetic factors influencing language processing.
Assuntos
Dislexia , Fenômenos Fisiológicos do Sistema Nervoso , Adolescente , Humanos , Adulto Jovem , Encéfalo/diagnóstico por imagem , Dislexia/diagnóstico por imagem , Dislexia/genética , Genótipo , Proteínas Associadas aos Microtúbulos/genética , LeituraRESUMO
Brain imaging work aimed at increased classification of dyslexia has underscored an important relationship between anterior (i.e., the inferior frontal gyrus; IFG) and posterior (i.e., superior temporal gyrus and supramarginal gyrus) brain regions. The extent to which the three components of the inferior frontal gyrus, namely the pars orbitalis, triangularis, and opercularis, are differentially related to the posterior regions, namely the superior temporal gyrus and supramarginal gyrus, needs further elucidation. Information about the nature of the anterior-posterior connections would facilitate our understanding of the neural underpinnings associated with dyslexia. Adult participants (N = 38; 16 with dyslexia) took part in an MRI study, whereby high-resolution structural scans were obtained. Volumetric asymmetry of the three regions of the IFG, the superior temporal gyrus, and the supramarginal gyrus was extracted. Significant differences were found for each of the three IFG regions, such that skilled readers had a greater leftward asymmetry of the orbitalis and triangularis, and greater rightward asymmetry of the opercularis, when compared to individuals with dyslexia. Furthermore, the pars triangularis was significantly associated with leftward asymmetry of the superior temporal gyrus for skilled but not dyslexic participants. For individuals with dyslexia, the cortical asymmetry of the IFG, and the corresponding connections with other reading-related brain regions, is inherently different from skilled readers. We discuss our findings in the context of the print-to-speech framework to further our understanding of the neural underpinnings associated with dyslexia.
Assuntos
Dislexia , Substância Cinzenta , Adulto , Humanos , Substância Cinzenta/diagnóstico por imagem , Dislexia/diagnóstico por imagem , Encéfalo , Leitura , Córtex Pré-Frontal , Mapeamento Encefálico , Imageamento por Ressonância Magnética/métodosRESUMO
We present a case study detailing cognitive performance, functional neuroimaging, and effects of a hypothesis-driven treatment in a 10-year-old girl diagnosed with complete, isolated corpus callosum agenesis. Despite having average overall intellectual abilities, the girl exhibited profound surface dyslexia and dysgraphia. Spelling treatment significantly and persistently improved her spelling of trained irregular words, and this improvement generalized to reading accuracy and speed of trained words. Diffusion weighted imaging revealed strengthened intrahemispheric white matter connectivity of the left temporal cortex after treatment and identified interhemispheric connectivity between the occipital lobes, likely facilitated by a pathway crossing the midline via the posterior commissure. This case underlines the corpus callosum's critical role in lexical reading and writing. It demonstrates that spelling treatment may enhance interhemispheric connectivity in corpus callosum agenesis through alternative pathways, boosting the development of a more efficient functional organization of the visual word form area within the left temporo-occipital cortex.
RESUMO
BACKGROUND: An intronic deletion within intron 2 of the DCDC2 gene encompassing the entire READ1 (hereafter, READ1d) has been associated in both children with developmental dyslexia (DD) and typical readers (TRs), with interindividual variation in reading performance and motion perception as well as with structural and functional brain alterations. Visual motion perception -- specifically processed by the magnocellular (M) stream -- has been reported to be a solid and reliable endophenotype of DD. Hence, we predicted that READ1d should affect neural activations in brain regions sensitive to M stream demands as reading proficiency changes. METHODS: We investigated neural activations during two M-eliciting fMRI visual tasks (full-field sinusoidal gratings controlled for spatial and temporal frequencies and luminance contrast, and sensitivity to motion coherence at 6%, 15% and 40% dot coherence levels) in four subject groups: children with DD with/without READ1d, and TRs with/without READ1d. RESULTS: At the Bonferroni-corrected level of significance, reading skills showed a significant effect in the right polar frontal cortex during the full-field sinusoidal gratings-M task. Regardless of the presence/absence of the READ1d, subjects with poor reading proficiency showed hyperactivation in this region of interest (ROI) compared to subjects with better reading scores. Moreover, a significant interaction was found between READ1d and reading performance in the left frontal opercular area 4 during the 15% coherent motion sensitivity task. Among subjects with poor reading performance, neural activation in this ROI during this specific task was higher for subjects without READ1d than for READ1d carriers. The difference vanished as reading skills increased. CONCLUSIONS: Our findings showed a READ1d-moderated genetic vulnerability to alterations in neural activation in the ventral attentive and salient networks during the processing of relevant stimuli in subjects with poor reading proficiency.
Assuntos
Dislexia , Lobo Frontal , Imageamento por Ressonância Magnética , Percepção de Movimento , Lobo Parietal , Leitura , Humanos , Dislexia/fisiopatologia , Dislexia/genética , Masculino , Criança , Feminino , Imageamento por Ressonância Magnética/métodos , Lobo Parietal/fisiopatologia , Percepção de Movimento/fisiologia , Lobo Frontal/fisiopatologia , Lobo Frontal/diagnóstico por imagem , Proteínas Associadas aos Microtúbulos/genética , Mapeamento Encefálico/métodos , Rede Nervosa/fisiopatologia , Rede Nervosa/diagnóstico por imagem , Estimulação Luminosa/métodosRESUMO
In the search for mechanisms that contribute to dyslexia, the term "attention" has been invoked to explain performance in a variety of tasks, creating confusion since all tasks do, indeed, demand "attention." Many studies lack an experimental manipulation of attention that would be necessary to determine its influence on task performance. Nonetheless, an emerging view is that children with dyslexia have an impairment in the exogenous (automatic/reflexive) orienting of spatial attention. Here we investigated the link between exogenous attention and reading ability by presenting exogenous spatial cues in the multi-letter processing task-a task relevant for reading. The task was gamified and administered online to a large sample of children (N = 187) between 6 and 17 years. Children with dyslexia performed worse overall at rapidly recognizing and reporting strings of letters. However, we found no evidence for a difference in the utilization of exogenous spatial cues, resolving two decades of ambiguity in the field. Previous studies that claimed otherwise may have failed to distinguish attention effects from overall task performance or found spurious group differences in small samples. RESEARCH HIGHLIGHTS: We manipulated exogenous visual spatial attention using pre-cues in a task that is relevant for reading and we see robust task effects of exogenous attention. We found no evidence for a deficit in utilizing exogenous spatial pre-cues in children with dyslexia. However, children with dyslexia showed reduced recognition ability for all letter positions. Children with dyslexia were just as likely to make letter transposition errors as typical readers.
Assuntos
Dislexia , Criança , Humanos , Atenção , Leitura , Sinais (Psicologia) , Cognição , Percepção VisualRESUMO
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.
Assuntos
Dislexia , Percepção da Fala , Criança , Humanos , Leitura , Som , Fala , Distúrbios da Fala , FonéticaRESUMO
The present longitudinal study investigated the hypothesis that early musical skills (as measured by melodic and rhythmic perception and memory) predict later literacy development via a mediating effect of phonology. We examined 130 French-speaking children, 31 of whom with a familial risk for developmental dyslexia (DD). Their abilities in the three domains were assessed longitudinally with a comprehensive battery of behavioral tests in kindergarten, first grade, and second grade. Using a structural equation modeling approach, we examined potential longitudinal effects from music to literacy via phonology. We then investigated how familial risk for DD may influence these relationships by testing whether atypical music processing is a risk factor for DD. Results showed that children with a familial risk for DD consistently underperformed children without familial risk in music, phonology, and literacy. A small effect of musical ability on literacy via phonology was observed, but may have been induced by differences in stability across domains over time. Furthermore, early musical skills did not add significant predictive power to later literacy difficulties beyond phonological skills and family risk status. These findings are consistent with the idea that certain key auditory skills are shared between music and speech processing, and between DD and congenital amusia. However, they do not support the notion that music perception and memory skills can serve as a reliable early marker of DD, nor as a valuable target for reading remediation. RESEARCH HIGHLIGHTS: Music, phonology, and literacy skills of 130 children, 31 of whom with a familial risk for dyslexia, were examined longitudinally. Children with a familial risk for dyslexia consistently underperformed children without familial risk in musical, phonological, and literacy skills. Structural equation models showed a small effect of musical ability in kindergarten on literacy in second grade, via phonology in first grade. However, early musical skills did not add significant predictive power to later literacy difficulties beyond phonological skills and family risk status.
Assuntos
Dislexia , Música , Humanos , Dislexia/genética , Dislexia/fisiopatologia , Estudos Longitudinais , Criança , Masculino , Feminino , Fatores de Risco , Leitura , Pré-Escolar , Percepção Auditiva/fisiologiaRESUMO
The prevalent "core phonological deficit" model of dyslexia proposes that the reading and spelling difficulties characterizing affected children stem from prior developmental difficulties in processing speech sound structure, for example, perceiving and identifying syllable stress patterns, syllables, rhymes and phonemes. Yet spoken word production appears normal. This suggests an unexpected disconnect between speech input and speech output processes. Here we investigated the output side of this disconnect from a speech rhythm perspective by measuring the speech amplitude envelope (AE) of multisyllabic spoken phrases. The speech AE contains crucial information regarding stress patterns, speech rate, tonal contrasts and intonational information. We created a novel computerized speech copying task in which participants copied aloud familiar spoken targets like "Aladdin." Seventy-five children with and without dyslexia were tested, some of whom were also receiving an oral intervention designed to enhance multi-syllabic processing. Similarity of the child's productions to the target AE was computed using correlation and mutual information metrics. Similarity of pitch contour, another acoustic cue to speech rhythm, was used for control analyses. Children with dyslexia were significantly worse at producing the multi-syllabic targets as indexed by both similarity metrics for computing the AE. However, children with dyslexia were not different from control children in producing pitch contours. Accordingly, the spoken production of multisyllabic phrases by children with dyslexia is atypical regarding the AE. Children with dyslexia may not appear to listeners to exhibit speech production difficulties because their pitch contours are intact. RESEARCH HIGHLIGHTS: Speech production of syllable stress patterns is atypical in children with dyslexia. Children with dyslexia are significantly worse at producing the amplitude envelope of multi-syllabic targets compared to both age-matched and reading-level-matched control children. No group differences were found for pitch contour production between children with dyslexia and age-matched control children. It may be difficult to detect speech output problems in dyslexia as pitch contours are relatively accurate.
Assuntos
Dislexia , Percepção da Fala , Criança , Humanos , Fala , Leitura , FonéticaRESUMO
As reading is inherently a multisensory, audiovisual (AV) process where visual symbols (i.e., letters) are connected to speech sounds, the question has been raised whether individuals with reading difficulties, like children with developmental dyslexia (DD), have broader impairments in multisensory processing. This question has been posed before, yet it remains unanswered due to (a) the complexity and contentious etiology of DD along with (b) lack of consensus on developmentally appropriate AV processing tasks. We created an ecologically valid task for measuring multisensory AV processing by leveraging the natural phenomenon that speech perception improves when listeners are provided visual information from mouth movements (particularly when the auditory signal is degraded). We designed this AV processing task with low cognitive and linguistic demands such that children with and without DD would have equal unimodal (auditory and visual) performance. We then collected data in a group of 135 children (age 6.5-15) with an AV speech perception task to answer the following questions: (1) How do AV speech perception benefits manifest in children, with and without DD? (2) Do children all use the same perceptual weights to create AV speech perception benefits, and (3) what is the role of phonological processing in AV speech perception? We show that children with and without DD have equal AV speech perception benefits on this task, but that children with DD rely less on auditory processing in more difficult listening situations to create these benefits and weigh both incoming information streams differently. Lastly, any reported differences in speech perception in children with DD might be better explained by differences in phonological processing than differences in reading skills. RESEARCH HIGHLIGHTS: Children with versus without developmental dyslexia have equal audiovisual speech perception benefits, regardless of their phonological awareness or reading skills. Children with developmental dyslexia rely less on auditory performance to create audiovisual speech perception benefits. Individual differences in speech perception in children might be better explained by differences in phonological processing than differences in reading skills.
Assuntos
Dislexia , Percepção da Fala , Criança , Humanos , Adolescente , Dislexia/psicologia , Leitura , Fonética , ConscientizaçãoRESUMO
Studies with individuals with developmental dyslexia (DD) have documented impaired perception of words and faces, both of which are domains of visual expertise for human adults. In this study, we examined a possible mechanism that might be associated with the impaired acquisition of visual expertise for words and faces in DD, namely, the atypical engagement of the monocular visual pathway. Participants with DD and typical readers (TR) judged whether a pair of sequentially presented unfamiliar faces or nonwords were the same or different, and the pair of stimuli were displayed in an eye-specific fashion using a stereoscope. Based on evidence of greater reliance on subcortical structures early in development, we predicted differences between the groups in the engagement of lower (monocular) versus higher (binocular) regions of the visual pathways. Whereas the TR group showed a monocular advantage for both stimulus types, the DD participants evinced a monocular advantage for faces and words that was much greater than that measured in the TRs. These findings indicate that the DD individuals have enhanced subcortical engagement and that this might arise from the failure to fine-tune cortical correlates mediating the discrimination of homogeneous exemplars in domains of expertise.
Assuntos
Dislexia , Percepção Visual , Adulto , Humanos , Vias Visuais , LeituraRESUMO
The purpose of this study is to identify consistencies across functional neuroimaging studies regarding common and unique brain regions/networks for individuals with reading difficulties (RD) and math difficulties (MD) compared to typically developing (TD) individuals. A systematic search of the literature, utilizing multiple databases, yielded 116 functional magnetic resonance imaging and positron emission tomography studies that met the criteria. Coordinates that directly compared TD with either RD or MD were entered into GingerALE (Brainmap.org). An activation likelihood estimate (ALE) meta-analysis was conducted to examine common and unique brain regions for RD and MD. Overall, more studies examined RD (n = 96) than MD (n = 20). Across studies, overactivation for reading and math occurred in the right insula and inferior frontal gyrus for atypically developing (AD) > TD comparisons, albeit in slightly different areas of these regions; however, inherent threshold variability across imaging studies could diminish overlying regions. For TD > AD comparisons, there were no similar or overlapping brain regions. Results indicate there were domain-specific differences for RD and MD; however, there were some similarities in the ancillary recruitment of executive functioning skills. Theoretical and practical implications for researchers and educators are discussed.
Assuntos
Dislexia , Leitura , Humanos , Dislexia/patologia , Funções Verossimilhança , Encéfalo , Cognição , Imageamento por Ressonância MagnéticaRESUMO
BACKGROUND: Developmental dyslexia, a complex neurodevelopmental disorder, not only affects children's academic performance but is also associated with increased healthcare costs, lower employment rates, and reduced productivity. The pathogenesis of dyslexia remains unclear and it is generally considered to be caused by the overlap of genetic and environmental factors. Systematically exploring the close relationship between exposure to environmental compounds and susceptibility genes in the development of dyslexia is currently lacking but high necessary. METHODS: In this study, we systematically compiled 131 publicly reported susceptibility genes for dyslexia sourced from DisGeNET, OMIM, and GeneCards databases. Comparative Toxicogenomics Database database was used to explore the overlap between susceptibility genes and 95 environmental compounds, including metals, persistent organic pollutants, polycyclic aromatic hydrocarbons, and pesticides. Chemical bias towards the dyslexia risk genes was taken into account in the observation/expectation ratios > 1 and the corresponding P value obtained by hypergeometric probability test. RESULTS: Our study found that the number of dyslexia risk genes targeted by each chemical varied from 1 to 109. A total of 35 chemicals were involved in chemical reactions with dyslexia-associated genes, with significant enrichment values (observed/expected dyslexia risk genes) ranging from 1.147 (Atrazine) to 66.901 (Dibenzo(a, h)pyrene). CONCLUSION: The results indicated that dyslexia-associated genes were implicated in certain chemical reactions. However, these findings are exploratory, and further research involving animal or cellular experiments is needed.
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Dislexia , Poluentes Ambientais , Predisposição Genética para Doença , Humanos , Dislexia/genética , Predisposição Genética para Doença/genética , Poluentes Ambientais/efeitos adversos , Hidrocarbonetos Policíclicos Aromáticos/efeitos adversos , ToxicogenéticaRESUMO
BACKGROUND: Developmental dyslexia (DD) is a neurodevelopmental disorder that is characterized by difficulties with all aspects of information acquisition in the written word, including slow and inaccurate word recognition. The neural basis behind DD has not been fully elucidated. METHOD: The study included 22 typically developing (TD) children, 16 children with isolated spelling disorder (SpD), and 20 children with DD. The cortical thickness, folding index, and mean curvature of Broca's area, including the triangular part of the left inferior frontal gyrus (IFGtriang) and the opercular part of the left inferior frontal gyrus, were assessed to explore the differences of surface morphology among the TD, SpD, and DD groups. Furthermore, the structural covariance network (SCN) of the triangular part of the left inferior frontal gyrus was analyzed to explore the changes of structural connectivity in the SpD and DD groups. RESULTS: The DD group showed higher curvature and cortical folding of the left IFGtriang than the TD group and SpD group. In addition, compared with the TD group and the SpD group, the structural connectivity between the left IFGtriang and the left middle-frontal gyrus and the right mid-orbital frontal gyrus was increased in the DD group, and the structural connectivity between the left IFGtriang and the right precuneus and anterior cingulate was decreased in the DD group. CONCLUSION: DD had atypical structural connectivity in brain regions related to visual attention, memory and which might impact the information input and integration needed for reading and spelling.
Assuntos
Dislexia , Criança , Humanos , Dislexia/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Leitura , Mapeamento Encefálico , Lobo Frontal , Imageamento por Ressonância MagnéticaRESUMO
In this systematic narrative review, we synthesised the small existing body of research on children who are gifted and dyslexic (G-D) in order to investigate the claim that G-D students have a unique profile, characterised by well-masked word-level reading and spelling difficulties. Our focus was on both the cognitive and academic profiles of this subgroup of twice-exceptional (2e) children and the assessment protocols used to identify them. Findings suggest that despite having processing deficits associated with dyslexia, G-D students' gifted strengths, especially those relating to oral language, may enable them to compensate for their reading difficulties, at least to an extent that they fail to meet standard diagnostic criteria. However, G-D students also perform poorly on word-level reading, reading fluency and spelling tasks when compared with both control groups and their gifted, non-dyslexic peers, providing clear evidence of impaired achievement. Findings from this review highlight the need for (a) a more nuanced approach to the assessment of students presenting with highly discrepant profiles and (b) future research into both the cognitive and academic profiles and the instructional needs of this highly able yet poorly understood group of students, whose potential may be masked and thus underestimated in the school setting.
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Criança Superdotada , Dislexia , Humanos , Dislexia/diagnóstico , Criança , LeituraRESUMO
Children with dyslexia (CwD) often report poor psychological well-being. We examined (i) whether anxiety, self-concept and reading motivation in CwD differed from those of typically developing children (TDC; case-control design, Study 1a) and (ii) whether these differences mirrored the linear relationships that these variables present with reading ability in the TDC group (dimensional approach, Study 1b). In Study 1a, 34 CwD were compared with 191 TDC in grades 4-8 on anxiety, self-concept, reading motivation and reading strategy using self-reports (controlling for sex, intelligence and math ability scores). In Study 1b, the differences that emerged in Study 1a were compared with the results obtained from a simulation procedure that generated dyslexia observations under the assumptions of a dimensional hypothesis. The CwD group presented small-to-moderate difficulties, which partially mirrored the predictions in the TDC group. However, violations of predictions based on the population without dyslexia were found for reading self-concept, social anxiety and reading competitiveness. In sum, children's diagnoses affect their self-perception as readers and social anxiety in a way that cannot be inferred from linear relationships. CwD need support to preserve an adequate image of themselves as readers and cope with social anxiety.
Assuntos
Ansiedade , Dislexia , Emoções , Motivação , Leitura , Autoimagem , Humanos , Dislexia/diagnóstico , Dislexia/psicologia , Criança , Feminino , Masculino , Motivação/fisiologia , Ansiedade/diagnóstico , Ansiedade/psicologia , Emoções/fisiologia , Estudos de Casos e ControlesRESUMO
Through a reflexive thematic analysis of a large online support group for dyslexia and a sensemaking lens, this study investigated how mothers made sense of their child's dyslexia through metaphors. Mothers used metaphors to characterise their feelings surrounding dyslexia, their school-based interactions and their identity as advocates. The language mothers use offers a generative, textured way to understand the lived experiences of supporting a child with learning differences. Whilst mothers articulated much frustration and anger, they also voiced encouragement, advice-giving, empathy and hope, illustrating how their sense of agency was both threatened and empowered by the experience of having a child with dyslexia. There is much mothers must process, understand and navigate surrounding their child's dyslexia and the findings underscore the need for early school-based screening, support and intervention.