Disrupted neural responses to phonological and orthographic processing in dyslexic children: an fMRI study

Temple, Elise; Poldrack, Russell A.; Salidis, Joanna; Deutsch, Gayle K.; Tallal, Paula; Merzenich, Michael M.; Gabrieli, John D. E.

doi:10.1097/00001756-200102120-00024

Cited by 325 publications

(265 citation statements)

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“…Converging evidence from many neuroimaging studies point toward a characteristic hypoactivation of left-hemispheric temporoparietal (44,46,(48)(49)(50)(51) and occipitotemporal (44,(46)(47)(48)50) brain regions in children and adults with DD compared with typical reading controls. Furthermore, reduced gray-matter volume indices in temporoparietal and occipitotemporal brain regions have been reported in prereading children at risk for DD compared with their peers (62).…”

Section: Discussionmentioning

confidence: 99%

“…[40][41][42]. In individuals with DD, a hypoactivation of the left temporoparietal region of the brain seems to reflect an inability to map the sounds of languages (phonemes) to its written counterparts (letters/graphemes) (44,(46)(47)(48)(49)(50)(51). The left hemispheric occipitotemporal region seems to be involved in the processing of words or pseudowords in typical reading children and adults (for reviews, see refs.…”

Section: Discussionmentioning

confidence: 99%

“…Crosssectional studies have demonstrated changes in these highly integrated reading networks depending on reading skill level (e.g., refs. 44 and 45) and converging evidence points toward a characteristic hypoactivation of temporoparietal as well as occipitotemporal brain areas in individuals with DD (44,[46][47][48][49][50][51][52][53][54][55].These functional characteristics in posterior brain regions in children and adults with DD have been complemented by anatomical abnormalities. Voxel-based morphometry reveals differences in gray-matter volume indices in individuals with DD (compared with typical reading controls) in various areas of the brain, including left occipitotemporal and temporoparietal areas (44,(56)(57)(58)(59)(60)(61), bilateral fusiform (59), and lingual gyrus (LG) (58) as well as the cerebellum (56-58).…”

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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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 97%

mentioning

confidence: 98%

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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

View full text Add to dashboard Cite

show abstract

“…Some studies on reading and rhyming in adults found more left inferior frontal activation for those with dyslexia than for controls (Brunswick et al, 1999;Rumsey et al, 1997;Shaywitz et al, 1998), but others reported more activation for controls (GrossGlenn et al, 1991;Paulesu et al, 1996). Also for children the results are rather inconsistent with dyslexia leading to either more (Georgiewa et al, 2002;Temple et al, 2001) or less activation in the inferior frontal gyrus (Bolger et al, 2008b;Booth et al, 2007;Booth et al, 2008;Cao et al, 2006;Georgiewa et al, 1999;Shaywitz et al, 2002). The meta-analyses by Richlan et al summarized the local activation differences between good and poor readers in the left inferior frontal gyrus with more pronounced activity in the anterior insula and primary motor cortex close to the mouth area and underactivation in the opercular part of the inferior frontal gyrus in poor readers.…”

Section: Introductionmentioning

confidence: 98%