Precursors of Literacy Delay among Children at Genetic Risk of Dyslexia

Gallagher, Alison; Frith, Uta; Snowling, Margaret J.

doi:10.1017/s0021963099005284

Cited by 287 publications

(249 citation statements)

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“…Converging evidence has since been reported by several studies of children at high risk of dyslexia before formal schooling begins (Byrne, Fielding-Barnsley, Ashley, & Larsen, 1997;Gallagher, Frith, & Snowling, 2000;Locke et al, 1997;Lyytinen, Poikkeus, Laakso, Eklund, & Lyytinen, 2001;Lefly & Pennington 1996). However, it needs to be borne in mind that this method of recruitment is very different from that used in more conventional group studies that have selected children who fulfill ÔdiscrepancyÕ and other more conventional criteria for reading disability.…”

Section: Dyslexia Across the Life-spanmentioning

confidence: 86%

Specific reading disability (dyslexia): what have we learned in the past four decades?

Vellutino

Fletcher

Snowling

et al. 2004

Child Psychology Psychiatry

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1,591

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We summarize some of the most important findings from research evaluating the hypothesized causes of specific reading disability (ÔdyslexiaÕ) over the past four decades. After outlining components of reading ability, we discuss manifest causes of reading difficulties, in terms of deficiencies in component reading skills that might lead to such difficulties. The evidence suggests that inadequate facility in word identification due, in most cases, to more basic deficits in alphabetic coding is the basic cause of difficulties in learning to read. We next discuss hypothesized deficiencies in readingrelated cognitive abilities as underlying causes of deficiencies in component reading skills. The evidence in these areas suggests that, in most cases, phonological skills deficiencies associated with phonological coding deficits are the probable causes of the disorder rather than visual, semantic, or syntactic deficits, although reading difficulties in some children may be associated with general language deficits. Hypothesized deficits in general learning abilities (e.g., attention, association learning, cross-modal transfer etc.) and low-level sensory deficits have weak validity as causal factors in specific reading disability. These inferences are, by and large, supported by research evaluating the biological foundations of dyslexia. Finally, evidence is presented in support of the idea that many poor readers are impaired because of inadequate instruction or other experiential factors. This does not mean that biological factors are not relevant, because the brain and environment interact to produce the neural networks that support reading acquisition. We conclude with a discussion of the clinical implications of the research findings, focusing on the need for enhanced instruction.

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Section: Dyslexia Across the Life-spanmentioning

confidence: 86%

Specific reading disability (dyslexia): what have we learned in the past four decades?

Vellutino

Fletcher

Snowling

et al. 2004

Child Psychology Psychiatry

Self Cite

2,051

1,591

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“…Two critical dimensions that may be important are the degree of phonological deficit and the degree of language impairment (Gallagher, Frith, & Snowling, 2000;Griffiths & Snowling, 2002;Joanisse et al, 2000;Manis, Seidenberg, Doi, McBride-Chang, & Petersen, 1996;Stanovich, Siegel, & Gottardo, 1997). According to the phonological representations hypothesis, the degree of phonological impairment should be the primary variable affecting gating task performance.…”

Section: Introductionmentioning

confidence: 99%

Auditory word identification in dyslexic and normally achieving readers

Bruno

Manis

Keating

et al. 2007

Journal of Experimental Child Psychology

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The integrity of phonological representation/processing in dyslexic children was explored with a gating task in which children listened to successively longer segments (gates) of a word. At each gate, the task was to decide what the entire word was. Responses were scored for overall accuracy as well as the children's sensitivity to coarticulation from the final consonant. As a group, dyslexic children were less able than normally achieving readers to detect coarticulation present in the vowel portion of the word, particularly on the most difficult items, namely those ending in a nasal sound. Hierarchical regression and path analyses indicated that phonological awareness mediated the relation of gating and general language ability to word and pseudoword reading ability.

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“…Phonological processing skills have been found to be a key predictor of later reading ability in preschool and elementary schoolaged children (19-31). In addition to phonological processing deficits, a range of other linguistic impairments have been observed in infants and prereading children who later exhibit weak reading scores, including speech perception (23, 26), syntax production, and comprehension (32-35), language comprehension (26), receptive vocabulary (22,34), and rapid automatized naming abilities (23,24,34,(36)(37)(38).With the advent of modern neuroimaging tools, it is now possible to study the neural substrates of reading and reading-related processes in the conscious human brain. Functional MRI (fMRI) studies have revealed a characteristic network of posterior brain areas typically involved in reading and reading-related tasks in children and adults including: (i) the dorsal or temporoparietal circuit (including lateral extrastriate and left inferior occipital areas) and (ii) the ventral or occipitotemporal circuit [including angular and supramarginal gyrus, inferior parietal lobe, and posterior aspects of the superior temporal gyrus (39-43)].…”

mentioning

confidence: 99%

“…Phonological processing skills have been found to be a key predictor of later reading ability in preschool and elementary schoolaged children (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). In addition to phonological processing deficits, a range of other linguistic impairments have been observed in infants and prereading children who later exhibit weak reading scores, including speech perception (23,26), syntax production, and comprehension (32)(33)(34)(35), language comprehension (26), receptive vocabulary (22,34), and rapid automatized naming abilities (23,24,34,(36)(37)(38).…”

mentioning

confidence: 99%

Functional characteristics of developmental dyslexia in left-hemispheric posterior brain regions predate reading onset

Raschle

Zuk²,

Gaab³

2012

Proc. Natl. Acad. Sci. U.S.A.

208

190

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Individuals with developmental dyslexia (DD) show a disruption in posterior left-hemispheric neural networks during phonological processing. Additionally, compensatory mechanisms in children and adults with DD have been located within frontal brain areas. However, it remains unclear when and how differences in posterior left-hemispheric networks manifest and whether compensatory mechanisms have already started to develop in the prereading brain. Here we investigate functional networks during phonological processing in 36 prereading children with a familial risk for DD (n = 18, average age = 66.50 mo) compared with age and IQ-matched controls (n = 18; average age = 65.61 mo). Functional neuroimaging results reveal reduced activation in prereading children with a family-history of DD (FHD + ), compared with those without (FHD − ), in bilateral occipitotemporal and left temporoparietal brain regions. This finding corresponds to previously identified hypoactivations in left hemispheric posterior brain regions for school-aged children and adults with a diagnosis of DD. Furthermore, left occipitotemporal and temporoparietal brain activity correlates positively with prereading skills in both groups. Our results suggest that differences in neural correlates of phonological processing in individuals with DD are not a result of reading failure, but are present before literacy acquisition starts. Additionally, no hyperactivation in frontal brain regions was observed, suggesting that compensatory mechanisms for reading failureare not yet present. Future longitudinal studies are needed to determine whether the identified differences may serve as neural premarkers for the early identification of children at risk for DD.is a specific learning disability that affects about 5-17% of all children (1, 2). DD is characterized by difficulties with accurate and fluent word recognition and poor spelling and decoding performance. DD cannot be accounted for by poor vision, hearing, or a lack of motivation. Molecular-genetic, twin, and family studies have shown a marked familial risk for DD, with an increasing prevalence in families with one or more members with a diagnosis of DD or reading difficulties (e.g., refs. 3 and 4). In addition, several DD susceptibility genes crucial for early brain development have been reported (5-8). DD can have severe social and psychological consequences (9-11) and may impact a child's life beyond their academic pursuits. Studies have shown that children with learning disabilities are less likely to complete high school (12) and are more likely to enter the juvenile justice system (13).Most researchers, clinicians, and reading specialists agree that DD typically results from a weakness in the ability to manipulate oral speech sounds of language (2,14). Individuals with DD are often unable to access the underlying sound structures of words, creating a difficulty in mapping sounds to written language (15-18). Phonological processing skills have been found to be a key predictor of later reading ability in pr...

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Precursors of Literacy Delay among Children at Genetic Risk of Dyslexia

Cited by 287 publications

References 0 publications

Specific reading disability (dyslexia): what have we learned in the past four decades?

Specific reading disability (dyslexia): what have we learned in the past four decades?

Auditory word identification in dyslexic and normally achieving readers

Functional characteristics of developmental dyslexia in left-hemispheric posterior brain regions predate reading onset

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