Dyslexia and Neuroscience: The Geschwind-Galaburda Hypothesis 30 Years Later
In: Extraordinary Brain
7 Ergebnisse
Sortierung:
In: Extraordinary Brain
In: Developmental science, Band 26, Heft 5
ISSN: 1467-7687
AbstractMusical training has long been viewed as a model for experience‐dependent brain plasticity. Reports of musical training‐induced brain plasticity are largely based on cross‐sectional studies comparing musicians to non‐musicians, which cannot address whether musical training itself is sufficient to induce these neurobiological changes or whether pre‐existing neuroarchitecture before training predisposes children to succeed in music. Here, in a longitudinal investigation of children from infancy to school age (n = 25), we find brain structure in infancy that predicts subsequent music aptitude skills at school‐age. Building on prior evidence implicating white matter organization of the corticospinal tract as a neural predisposition for musical training in adults, here we find that structural organization of the right corticospinal tract in infancy is associated with school‐age tonal and rhythmic musical aptitude skills. Moreover, within the corpus callosum, an inter‐hemispheric white matter pathway traditionally linked with musical training, we find that structural organization of this pathway in infancy is associated with subsequent tonal music aptitude. Our findings suggest predispositions prior to the onset of musical training from as early as infancy may serve as a scaffold upon which ongoing musical experience can build.Research Highlights
Structural organization of the right corticospinal tract in infancy is associated with school‐age musical aptitude skills.
Longitudinal associations between the right corticospinal tract in infancy and school‐age rhythmic music aptitude skills remain significant even when controlling for language ability.
Findings support the notion of predispositions for success in music, and suggest that musical predispositions likely build upon a neural structural scaffold established in infancy.
Findings support the working hypothesis that a dynamic interaction between predisposition and experience established in infancy shape the trajectory of long‐term musical development.
In: Families in society: the journal of contemporary human services, Band 103, Heft 3, S. 269-280
ISSN: 1945-1350
Dyslexia, the most common learning disability, is associated with poor academic, economic, vocational, and health outcomes. Disproportionately, dyslexia is undiagnosed and untreated in children who are Black, Indigenous, and people of color (BIPOC) or who live in poverty. Early identification of and subsequent interventions for children at risk for dyslexia can effectively mitigate poor outcomes. While screening and interventions largely occur in schools, social workers across practice contexts have responsibilities to address dyslexia: identifying, referring, educating, and advocating. Social workers should address dyslexia to promote equity and improve quality of life and various outcomes across the life course. This article describes dyslexia, early screening, and interventions; dyslexia as a social justice issue; and social workers' roles in addressing dyslexia.
In: Developmental science, Band 20, Heft 5
ISSN: 1467-7687
AbstractResearch suggests that early identification of developmental dyslexia is important for mitigating the negative effects of dyslexia, including reduced educational attainment and increased socioemotional difficulties. The strongest pre‐literacy predictors of dyslexia are rapid automatized naming (RAN), phonological awareness (PA), letter knowledge, and verbal short‐term memory. The relationship among these constructs has been debated, and several theories have emerged to explain the unique role of each in reading ability/disability. Furthermore, the stability of identification of risk based on these measures varies widely across studies, due in part to the different cut‐offs employed to designate risk. We applied a latent profile analysis technique with a diverse sample of 1215 kindergarten and pre‐kindergarten students from 20 schools, to investigate whether PA, RAN, letter knowledge, and verbal short‐term memory measures differentiated between homogenous profiles of performance on these measures. Six profiles of performance emerged from the data: average performers, below average performers, high performers, PA risk, RAN risk, and double‐deficit risk (both PA and RAN). A latent class regression model was employed to investigate the longitudinal stability of these groups in a representative subset of children (n = 95) nearly two years later, at the end of 1st grade. Profile membership in the spring semester of pre‐kindergarten or fall semester of kindergarten was significantly predictive of later reading performance, with the specific patterns of performance on the different constructs remaining stable across the years. There was a higher frequency of PA and RAN deficits in children from lower socioeconomic status (SES) backgrounds. There was no evidence for the IQ–achievement discrepancy criterion traditionally used to diagnose dyslexia. Our results support the feasibility of early identification of dyslexia risk and point to the heterogeneity of risk profiles. These findings carry important implications for improving outcomes for children with dyslexia, based on more targeted interventions.
In: Developmental science, Band 21, Heft 5
ISSN: 1467-7687
AbstractA functional region of left fusiform gyrus termed "the visual word form area" (VWFA) develops during reading acquisition to respond more strongly to printed words than to other visual stimuli. Here, we examined responses to letters among 5‐ and 6‐year‐old early kindergarten children (N = 48) with little or no school‐based reading instruction who varied in their reading ability. We used functional magnetic resonance imaging (fMRI) to measure responses to individual letters, false fonts, and faces in left and right fusiform gyri. We then evaluated whether signal change and size (spatial extent) of letter‐sensitive cortex (greater activation for letters versus faces) and letter‐specific cortex (greater activation for letters versus false fonts) in these regions related to (a) standardized measures of word‐reading ability and (b) signal change and size of face‐sensitive cortex (fusiform face area or FFA; greater activation for faces versus letters). Greater letter specificity, but not letter sensitivity, in left fusiform gyrus correlated positively with word reading scores. Across children, in the left fusiform gyrus, greater size of letter‐sensitive cortex correlated with lesser size of FFA. These findings are the first to suggest that in beginning readers, development of letter responsivity in left fusiform cortex is associated with both better reading ability and also a reduction of the size of left FFA that may result in right‐hemisphere dominance for face perception.
In: Developmental science, Band 24, Heft 1
ISSN: 1467-7687
AbstractRecent efforts have focused on screening methods to identify children at risk for dyslexia as early as preschool/kindergarten. Unfortunately, while low sensitivity leads to under‐identification of at‐risk children, low specificity can lead to over‐identification, resulting in inaccurate allocation of limited educational resources. The present study focused on children identified as at‐risk in kindergarten who do not subsequently develop poor reading skills to specify factors associated with better reading outcomes among at‐risk children. Early screening was conducted in kindergarten and a subset of children was tracked longitudinally until second grade. Potential protective factors were evaluated at cognitive‐linguistic, environmental, and neural levels. Relative to at‐risk kindergarteners with subsequent poor reading, those with typical reading outcomes were characterized by significantly higher socioeconomic status (SES), speech production accuracy, and structural organization of the posterior right‐hemispheric superior longitudinal fasciculus (SLF). A positive association between structural organization of the right SLF and subsequent decoding skills was found to be specific to at‐risk children and not observed among typical controls. Among at‐risk children, several kindergarten‐age factors were found to significantly contribute to the prediction of subsequent decoding skills: white matter organization in the posterior right SLF, age, gender, SES, and phonological awareness. These findings suggest that putative compensatory mechanisms are already present by the start of kindergarten. The right SLF, in conjunction with the cognitive‐linguistic and socioeconomic factors identified, may play an important role in facilitating reading development among at‐risk children. This study has important implications for approaches to early screening, and assessment strategies for at‐risk children.
In: Developmental science, Band 22, Heft 5
ISSN: 1467-7687
AbstractChildhood poverty has been associated with structural and functional alterations in the developing brain. However, poverty does not alter brain development directly, but acts through associated biological or psychosocial risk factors (e.g. malnutrition, family conflict). Yet few studies have investigated risk factors in the context of infant neurodevelopment, and none have done so in low‐resource settings such as Bangladesh, where children are exposed to multiple, severe biological and psychosocial hazards. In this feasibility and pilot study, usable resting‐state fMRI data were acquired in infants from extremely poor (n = 16) and (relatively) more affluent (n = 16) families in Dhaka, Bangladesh. Whole‐brain intrinsic functional connectivity (iFC) was estimated using bilateral seeds in the amygdala, where iFC has shown susceptibility to early life stress, and in sensory areas, which have exhibited less susceptibility to early life hazards. Biological and psychosocial risk factors were examined for associations with iFC. Three resting‐state networks were identified in within‐group brain maps: medial temporal/striatal, visual, and auditory networks. Infants from extremely poor families compared with those from more affluent families exhibited greater (i.e. less negative) iFC in precuneus for amygdala seeds; however, no group differences in iFC were observed for sensory area seeds. Height‐for‐age, a proxy for malnutrition/infection, was not associated with amygdala/precuneus iFC, whereas prenatal family conflict was positively correlated. Findings suggest that it is feasible to conduct infant fMRI studies in low‐resource settings. Challenges and practical steps for successful implementations are discussed.