The development of reading impairment: A cognitive neuroscience model

A wide number of neuroimaging studies converge on reduced recruitment of left perisylvian regions by dyslexic individuals during phonologically challenging tasks.

“This line of reasoning has resulted in a wide number of studies converging on the same conclusion: there is a reduced tendency of dyslexic individuals to recruit left perisylvian regions when faced with a phonologically challenging task.”

• cites Shaywitz et al., 1998Not checked yet

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Recent studies provide strongly converging data that perception of visual word forms reliably activates the left fusiform gyrus more than control visual stimuli.

“Recent studies have produced strongly converging data supporting the claim that the perception of visual word forms reliably activates the left fusiform gyrus in a way that other stimuli that control for visual stimulation do not”

• cites Price et al., 1997Not checked yet

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• cites Puce et al., 1996Not checked yet

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• cites Brunswick et al., 1999Not checked yet

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Neuroimaging studies have demonstrated that dyslexic adults typically under-activate the Visual Word Form Area during word reading tasks.

“A number of neuroimaging studies have demonstrated that, in contrast to nonimpaired readers, dyslexic adults typically under-activate this region during word reading tasks (See Table 1, items marked FG).”

• cites Table 1Not checked yet

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A specific pattern of linguistic deficits related to phonological processing significantly predicts the emergence of reading difficulties.

“A very specific pattern of linguistic deficits associated with phonological processing has been found to significantly predict the emergence of reading difficulties [Bradley and Bryant, 1983;Bishop and Adams, 1990;Gathercole and Baddeley, 1987].”

• cites Bradley and Bryant, 1983Not checked yet

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• cites Bishop and Adams, 1990Not checked yet

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• cites Gathercole and Baddeley, 1987Not checked yet

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Developmental dyslexia is linked to a core cognitive deficit in phonological awareness tasks that require analyzing and synthesizing sounds within syllables.

“This research suggests that developmental dyslexia is linked to a core cognitive deficit in phonological awareness tasks that require analysis and synthesis of the sounds within syllables [Wagner et al., 1997].”

• cites Wagner et al., 1997Not checked yet

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Even subtle phonological demands in deciding whether letter names rhyme produce differential STG recruitment in dyslexics and controls.

“Even the subtle phonological demands inherent in deciding whether the names of two letters rhyme produce differential recruitment of the STG region in dyslexics and controls [Paulesu et al., 1996].”

• cites Paulesu et al., 1996Not checked yet

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In children with phonological processing deficits, typical development of rapid and automatic word recognition is disrupted.

“and the typical development of rapid and automatic word recognition ability is therefore disrupted in children with phonological processing deficits.”

Reduced left perisylvian recruitment has been proposed as a candidate hallmark neurophysiological phenotype of developmental dyslexia.

“This common finding has been proposed as a candidate for a hallmark neurophysiological phenotype of developmental dyslexia [Shaywitz et al., 1998].”

• cites Shaywitz et al., 1998Not checked yet

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Across cognitive neuroscience methods, evidence consistently indicates dysfunction in developmental dyslexia in a left perisylvian area typically involving the superior temporal gyrus.

“Across several methodologies within cognitive neuroscience, evidence consistently points to two cortical areas that exhibit dysfunction in developmental dyslexia, and which, we propose, subserve the normal development of the cognitive achievement of reading.”

• cites Price et al., 1997Not checked yet

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• cites Rumsey et al., 1997aNot checked yet

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• cites Shaywitz et al., 1998Not checked yet

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A left occipito-temporal extrastriate visual region centered on or near the middle fusiform gyrus is associated with automatic visual word form perception in skilled adult readers.

“The second region-a portion of the left occipito-temporal extrastriate visual system typically centered on or near the middle portion of the fusiform gyrus-has been associated with the automatic process of visual word form perception in skilled adult readers.”

The left perisylvian area, typically involving the superior temporal gyrus, is involved in phonological processing.

“The first region-a left perisylvian area typically involving the superior temporal gyrus (STG)-is involved in phonological processing, and demonstrates significant structural and functional differences be-tween dyslexic and nonimpaired individuals.”

• cites Price et al., 1997Not checked yet

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• cites Rumsey et al., 1997aNot checked yet

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Dyslexic and nonimpaired individuals show significant structural and functional differences in the left perisylvian/STG region.

“The first region-a left perisylvian area typically involving the superior temporal gyrus (STG)-is involved in phonological processing, and demonstrates significant structural and functional differences be-tween dyslexic and nonimpaired individuals.”

Converging evidence supports a core phonological processing deficit as a candidate cognitive phenotype of developmental dyslexia.

“Converging evidence has led to one candidate cognitive phenotype of developmental dyslexia, namely an underlying core deficit in phonological processing abilities [for a review see National Reading Panel, 2000].”

• cites National Reading Panel, 2000Not checked yet

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As phonological demands increase, dyslexics show relative underactivation of posterior regions including left posterior superior temporal and angular gyri, and marginally reduced activity in the inferior lateral extrastriate area.

“As phonological demands increased, dyslexics exhibited a relative underactivation of posterior regions, including the left posterior superior temporal and angular gyri, as well as marginally reduced activity in the inferior lateral extrastriate area.”

• cites Shaywitz et al., 1998Not checked yet

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The left perisylvian and left fusiform regions interact during typical reading development.

“We suggest below that these two regions interact during the typical development of reading skills.”

Dyslexic individuals often produce greater activation in other brain regions compared to controls.

“dyslexic individuals often produce greater activation in other brain regions, as compared to control subjects.”

Reading impairments are associated with decreased anisotropy bilaterally in white matter of temporoparietal regions.

“Reading impairments were associated with decreased an- isotropy bilaterally in the white matter of temporoparietal regions.”

• cites Klingberg et al., 2000Not checked yet

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Phonological ability and degree of asymmetry in planum temporale are correlated in normal and reading-impaired children even when handedness, IQ, and SES are taken into account.

“phonological ability and degree of asymmetry in the planum temporale are correlated both in normal and reading-impaired children, even when handedness, IQ, and socioeconomic status (SES) are taken into account [Eckert et al., 2001].”

• cites Eckert et al., 2001Not checked yet

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The Visual Word Form Area is sensitive to the organization of letters within a word form; familiar words and pseudowords produce greater responses than randomly ordered strings or consonant strings.

“Both familiar words and novel letter strings that follow the patterns of the writing system (i.e., pseudowords such as 'blard') typically produce greater responses than randomly ordered strings, or strings of consonants [McCandliss et al., 2003a].”

• cites McCandliss et al., 2003aNot checked yet

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Skilled readers develop visual expertise that allows automatic combination of letters of a word form into an integrated visual percept within about 200 milliseconds.

“Skilled readers develop a form of visual expertise that allows them to automatically combine the letters of a word form into an integrated visual percept within approximately 200 milliseconds [for review see Rayner and Pollatsek, 1995].”

• cites Rayner and Pollatsek, 1995Not checked yet

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A similar correlation was reported in a nearby perisylvian region closer to parietal areas.

“A similar correlation was reported by Habib and Robichon [1996] in a nearby perisylvian region closer to parietal areas.”

• cites Habib and Robichon, 1996Not checked yet

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Skilled readers typically require less than a quarter of a second to form a stable representation of a visual word.

“skilled readers typically require less than a quarter of a second to form a stable representation of a visual word.”

Later stages of skilled reading development are linked to specialization of response properties of the left extrastriate visual system.

“A number of neuroimaging, electrophysiological and anatomical studies provide evidence that the later stages of skilled reading development are linked to a specialization of response properties of this portion of the extrastriate visual system.”

ERPs over posterior visual regions show sensitivity within 150-200 ms to differences between visual words and control stimuli including consonant strings.

“Event related potentials (ERPs) recorded over posterior visual regions demonstrate sensitivity within 150 -200 msec to differences between presentations of visual words and other stimuli that control for visual features [Bentin et al., 1999] including consonant strings”

• cites Bentin et al., 1999Not checked yet

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• cites Compton et al., 1991Not checked yet

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• cites McCandliss et al., 1997Not checked yet

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Responsiveness of the Visual Word Form Area is highly specific to visually presented alphabetic characters, producing greater response than auditory words or false font characters.

“Responsiveness of the Visual Word Form Area has been shown to be highly specific to visually presented alphabetic characters, which produce a greater response than either auditory words [Dehaene et al., 2002] or visually presented false font characters that control for low-level visual qualities”

• cites Dehaene et al., 2002Not checked yet

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• cites Price et al., 1997Not checked yet

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• cites Garrett et al., 2000Not checked yet

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Across four independent samples, the Visual Word Form Area has been discretely localized in approximately 90% of subjects via contrasts between words and other visual stimuli.

“Across four independent samples, the Visual Word Form Area has been discretely localized in approximately 90% of subjects via contrasts between words and other visual stimuli such as checkerboards, pseudo-letters, and random letter strings”

• cites Cohen et al., 2000Not checked yet

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• cites Dehaene et al., 2001Not checked yet

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• cites Cohen et al., 2002Not checked yet

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Rapid visual word recognition is supported by specialization of an extrastriate visual region that slowly emerges over the first several years of reading experience.

“This rapid visual word recognition ability is supported by a specialization of a region in the extrastriate visual system that slowly emerges over the first several years of reading experience [Posner and Mc-Candliss, 1999].”

• cites Posner and Mc-Candliss, 1999Not checked yet

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In the majority of neuroimaging studies, dyslexic subjects performed more poorly on tasks than controls on accuracy and reaction time.

“in the majority of the above studies, dyslexic subjects generally performed more poorly on tasks than did controls, as evidenced by accuracy and reaction time measures.”

Taken together, these studies support that individual differences in perisylvian structures systematically translate into individual differences in function, paralleling DTI literature.

“Taken together, these two studies support the notion that individual differences in perisylvian structures systematically translate into individual differences in function, a finding which has a close parallel in the DTI literature [Klingberg et al., 2000].”

• cites Klingberg et al., 2000Not checked yet

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Studies quantifying phonological abilities on a continuum have demonstrated robust correlations between such cognitive skills and asymmetries in perisylvian brain regions.

“Studies that have opted to quantify phonological abilities on a continuum rather than to focus on categorical distinctions between dyslexics and nonimpaired readers have demonstrated robust correlations between such cognitive skills and asymmetries in perisylvian brain regions.”

Populations with reading difficulties exhibit anomalous anatomy of left perisylvian structures.

“Populations with reading difficulties have been found to exhibit anomalous anatomy of left perisylvian structures.”

Activation of the Visual Word Form Area tends to cluster around similar Talairach coordinates with a standard deviation of approximately 5 mm.

“Across these studies, activation of the Visual Word Form Area tends to reliably cluster around similar Talairach coordinates (i.e., x ϭ -43,y ϭ -54, z ϭ -12) with a standard deviation of approximately 5 mm.”

The degree of anisotropy in a left temporoparietal region is highly correlated with reading skill across dyslexic and control subjects.

“the degree of anisotropy in a left temporoparietal region was highly correlated with reading skill, across both dyslexic and control subjects.”

• cites Klingberg et al., 2000Not checked yet

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The correlation between reading and anisotropy has been replicated in children and adolescents.

“this finding has recently been replicated in a group of children and adolescents, demonstrating the same pattern of correlation between reading and anisotropy [Nagy et al. 2002].”

• cites Nagy et al. 2002Not checked yet

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Visual Word Form Area responses are sensitive to words even under subliminal presentation conditions with chance detection, suggesting activation without conscious awareness.

“responses in the Visual Word Form Area have also been demonstrated to be sensitive to the presentation of words even under subliminal presentation conditions which produce chance levels of stimulus detection, suggesting that this region can be activated even in the absence of conscious awareness [Dehaene et al., 2001].”

• cites Dehaene et al., 2001Not checked yet

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fMRI studies in younger populations have generally found results consistent with the adult literature on dyslexia.

“The use of functional magnetic resonance imaging (fMRI) with younger populations has recently permitted the investigation of these phenomena in children, and such studies have generally found results consistent with the adult literature”

The neurobiological phenotype of reduced left perisylvian recruitment has been demonstrated even in dyslexics performing a letter rhyming task at accuracy equal to controls.

“the neurobiological phenotype described above has been demonstrated even in a group of dyslexics performing a letter rhyming task at levels of accuracy equal to those of control subjects [Paulesu et al., 1996].”

• cites Paulesu et al., 1996Not checked yet

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These studies provide further evidence that specialization within left extrastriate regions supports rapid word recognition in skilled readers.

“These studies provide further evidence that specialization within left extrastriate regions of the visual system supports rapid word recognition abilities in skilled readers.”

In four-, seven-, and ten-year-old children, only at age ten did a small and delayed N200 begin to show sensitivity to words over consonant strings.

“In investigating the potential emergence of similar effects in four, seven, and ten-year-old children, it was revealed that only at age ten did a small and delayed N200 begin to demonstrate sensitivity to words over consonant strings [McCandliss et al., 1997;Posner and McCandliss, 1999].”

• cites McCandliss et al., 1997Not checked yet

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• cites Posner and McCandliss, 1999Not checked yet

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Critical evidence that the Visual Word Form Area is necessary for perception of word forms rather than merely associated with reading comes from lesion analyses of pure alexia/word form dyslexia.

“Critical evidence establishing that the Visual Word Form Area is necessary for the perception of word forms rather than simply associated with reading comes from anatomical lesion analyses of a specific syndrome of functional loss known as word form dyslexia, pure alexia, or letterby-letter reading [Warrington and Shallice, 1980].”

• cites Warrington and Shallice, 1980Not checked yet

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Activity in the Visual Word Form Area reflects a form of perceptual expertise akin to object recognition, in which extensive experience with a class of visual objects leads to specialized domain-specific response properties of a fusiform area.

“activity in the Visual Word Form Area appears to reflect a form of perceptual expertise, akin to that seen in certain domains of object recognition [see Gauthier and Tarr, 2002, for review], in which extensive experience with a class of visual objects leads to specialized, domain-specific response properties of a fusiform area.”

• cites Gauthier and Tarr, 2002Not checked yet

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This specialization enhances perception within that domain.

“This specialization in turn serves to enhance perception within that domain.”

Dyslexic individuals may demonstrate an atypical response pattern in the Visual Word Form Area.

“Since evidence links visual word form processing to left-mid fusiform areas, it stands to reason that dyslexic individuals, who typically demonstrate great difficulty in rapidly identifying visual words, may demonstrate an atypical response pattern in the Visual Word Form Area.”

When a word is presented visually, dyslexics activate the Visual Word Form Area less than nonimpaired readers, both in explicit reading tasks and in implicit word vs false font contrasts.

“when a word is presented visually, dyslexics activate the Visual Word Form Area less than nonimpaired readers, both within tasks that explicitly require reading words, and also for tasks that do not require reading, but allow for implicit contrasts between presentation of words and false fonts [Brunswick et al., 1999].”

• cites Brunswick et al., 1999Not checked yet

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The correlation suggests that how well a child decodes is related to how much experience tunes the left fusiform gyrus to respond to orthographic structure.

“This correlation suggests a significant relationship between the degree to which a child might successfully engage in decoding and the degree to which his or her left fusiform gyrus becomes tuned via experience to become responsive to the orthographic structure of the writing system.”

Attention to those regularities may be critical for the gradual specialization of VWFA response properties.

“In normally developing children, successful application of decoding skill may then serve to focus attention on the regularities of grapheme-phoneme mapping in the writing system, making those regularities more salient; this attentional factor may serve a critical role in the gradual specialization of the response properties of the VWFA.”

In dyslexics, there are no significant positive correlations between angular gyrus activation and STG, IFG, fusiform, or lingual gyri.

“In dyslexics, however, there were no significant positive correlations between activation in the angular gyrus and STG, IFG, or the fusiform or lingual gyri.”

• cites Horwitz et al., 1998Not checked yet

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For reading tasks, the Visual Word Form Area might account for more variance in performance between dyslexic and nonimpaired groups.

“This suggests that, for reading tasks, the Visual Word Form Area might account for more variance in performance between dyslexic and nonimpaired groups.”

Left perisylvian functional anomalies may cause childhood phonological processing deficits that are important for grapheme-phoneme decoding.

“This suggests a developmental sequence in which functional anomalies in left perisylvian regions may lead to childhood deficits in phonological processing skills that are crucial for grapheme-phoneme decoding.”

Dyslexia involves a functional disconnection between the angular gyrus and perisylvian and extrastriate temporooccipital regions.

“The authors thus conclude that dyslexia involves a functional disconnection between the angular gyrus and perisylvian and extrastriate temporooccipital regions.”

• cites Horwitz et al., 1998Not checked yet

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In typically developing children, successful decoding may direct attention to grapheme-phoneme regularities in writing, increasing their salience.

“In normally developing children, successful application of decoding skill may then serve to focus attention on the regularities of grapheme-phoneme mapping in the writing system, making those regularities more salient; this attentional factor may serve a critical role in the gradual specialization of the response properties of the VWFA.”

Across a number of studies, damage restricted to the left ventro-temporal area leads to word form dyslexia.

“Binder and Mohr [1992] demonstrated that across a number of studies, damage restricted to the left ventro-temporal area leads to word form dyslexia.”

• cites Binder and Mohr, 1992Not checked yet

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Phonological deficits are directly associated with problems in grapheme-phoneme decoding.

“Phonological deficits have been directly linked to difficulties in grapheme-phoneme decoding [for review, see National Reading Panel, 2000].”

• cites National Reading Panel, 2000Not checked yet

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During early reading, small differences in decoding ability may affect the gradual VWFA specialization that enables automatic responses to writing-system regularities.

“Throughout the early years of reading, subtle differences in decoding ability may impact the gradual specialization of the VWFA that allows it to respond automatically to regularities with the writing system.”

In adults, an N200 ERP component over posterior visual areas differentiates familiar words from consonant strings.

“McCandliss and colleagues investigated the development of the VWFA by tracking the development of an N200 ERP component that, in adults, demonstrates a focus over posterior visual areas that differentiated familiar words from consonant strings [McCandliss et al., 1997].”

• cites McCandliss et al., 1997Not checked yet

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In the case of visual words, this perceptual expertise supports rapid integration of letters into a perceptual word-form.

“In the case of visual words, this perceptual expertise appears to support the rapid integration of letters into a perceptual word-form.”

Similar functional contrasts and time frames have been found using Magnetic Source Imaging and intracranial electrical recordings in regions consistent with fMRI coordinates for the Visual Word Form Area.

“Similar functional contrasts and time frames have been found using Magnetic Source Imaging [Tarkiainen et al., 1999;2002;Salmelin et al., 1996;Helenius et al., 1999] and intracranial electrical recordings [Nobre, 1994], in regions consistent with the fMRI coordinates for the Visual Word Form Area.”

• cites Tarkiainen et al., 1999Not checked yet

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• cites Salmelin et al., 1996Not checked yet

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• cites Nobre, 1994Not checked yet

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The difference in activity between dyslexics and controls was more pronounced in the Visual Word Form Area than in left STG regions.

“both of the above studies demonstrated that the difference in activity between dyslexics and controls was more pronounced in the Visual Word Form Area than in the left STG regions discussed above (see Table 1).”

• cites Brunswick et al., 1999Not checked yet

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• cites Paulesu et al., 2001Not checked yet

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Decoding ability causally contributes to VWFA specialization.

“The notion that decoding ability plays a causal role in the specialization of the VWFA provides a pathway through which disrupted function of perisylvian regions could have a potentially cascading influence on the specialization processes that occur in left fusiform areas during literacy acquisition.”

Paulesu et al. demonstrated the same Visual Word Form Area contrast between dyslexics and nonimpaired readers across English and Italian writing systems.

“Paulesu et al. [2001] demonstrated this same Visual Word Form Area contrast between dyslexics and nonimpaired readers across several writing systems, including both English, in which the lettersound mapping is complex, and Italian, in which the relationship is much more direct.”

• cites Paulesu et al., 2001Not checked yet

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The authors propose that abnormalities in perisylvian areas supporting phonology may cascade onto the development of rapid word recognition while the VWFA is becoming specialized to writing-system regularities.

“We propose that functional and structural abnormalities in the perisylvian regions that subserve phonological processing may have a cascading effect on the development of rapid word recognition processes during the years when the VWFA is becoming increasingly specialized to respond to regularities within the writing system.”

• AssumptionThe authors state this as an assumption: Little is known about the mechanism by which functional properties of perisylvian regions associated with phonology influence the development of visual expertise effects supported by the fusiform gyrus.

Children with mild to severe reading impairments can benefit substantially from interventions that explicitly train phonological awareness and alphabetic decoding.

“Several studies have provided strong support for the claim that children with mild to severe reading impairments can benefit significantly from intervention techniques that involve explicit training and support in phonological awareness training and alphabetic decoding skills [Foorman et al., 1998;Vellutino et al., 1996;Torgesson et al., 2001].”

• cites Foorman et al., 1998Not checked yet

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• cites Vellutino et al., 1996Not checked yet

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• cites Torgesson et al., 2001Not checked yet

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SES-related differences in reading, language, and phonological skills have been empirically linked to environmental factors such as home literacy environment characteristics.

“These differences have been empirically tied to environmental factors, such as characteristics of home literacy environments [Payne et al., 1994].”

• cites Payne et al., 1994Not checked yet

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Reading, language, and phonological measures are especially affected by socioeconomic status differences.

“Although children from socioeconomically disadvantaged homes perform significantly worse on many measures of academic ability and achievement [Smith et al., 1997;Duncan et al., 1998;Haveman and Wolfe, 1995], measures of reading, language, and phonological skills are particularly influenced by differences in socioeconomic status (SES) [see Whitehurst, 1997;Lonigan et al., 1998].”

• cites Whitehurst, 1997Not checked yet

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• cites Lonigan et al., 1998Not checked yet

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Different pathways to poor phonological decoding may each harm VWFA specialization similarly.

“Finally, one implication raised by this cascading model of developmental reading disabilities is that multiple pathways leading to poor phonological decoding ability might have the same negative impact on the specialization of the VWFA.”

Nonimpaired children's neural profiles remained unchanged during the study.

“The neural profiles of nonimpaired children did not change over the course of the study.”

• cites Simos et al., 2002Not checked yet

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The developmental cognitive neuroscience methods reviewed in the special issue have yielded converging results that can be synthesized into an account of dyslexia's biological bases.

“In sum, the various methods of developmental cognitive neuroscience reviewed in this special issue have produced converging results that can be synthesized into an account of the biological bases of developmental dyslexia.”

The changes observed were specific to decodable letter strings.

“A similar within-subject control task involving nondecodable consonant strings demonstrated no such change over the course of the study, suggesting that the observed changes were specific to decodable letter strings.”

Subtle phonological impairments can cause reading development problems resembling most dyslexia symptoms.

“Such models have demonstrated that subtle impairments in phonology can lead to reading development problems that parallel most of the symptoms of developmental dyslexia, and can also be used to investigate principles by which particular intervention protocols can lead to generalizable changes in performance [Harm et al., 2003].”

• cites Harm and Seidenberg, 1999Not checked yet

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• cites Harm et al., 2003Not checked yet

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In a magnetic source imaging study, dyslexic children had relatively lower left posterior superior temporal gyrus activation than nonimpaired children during a phonological task.

“One study used magnetic source imaging to demonstrate the typical neural profile described earlier, in which dyslexic children showed relatively decreased activation of the left posterior superior temporal gyrus during a phonologically challenging task, relative to nonimpaired children [Simos et al., 2002].”

• cites Simos et al., 2002Not checked yet

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These two factors have additive, noninteracting effects on phonological skill.

“Since these two factors demonstrate additive (i.e., noninteracting) effects on phonological skill, an intriguing possibility is raised.”

• cites Eckert et al., 2001Not checked yet

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Research has identified separable heritability patterns and genetic linkages for phonological awareness, decoding, and orthographic skill.

“The development of specific cognitive phenotypes has allowed research to isolate separable heritability patterns and genetic linkages for phonological awareness and decoding and orthographic skill [see Olson 2002, for a review].”

• cites Olson 2002Not checked yet

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The phonological awareness and decoding interventions directly reversed a key neurobiological hallmark of dyslexia: limited left superior temporal gyrus recruitment during phonological challenge.

“These studies suggest that the phonological awareness and decoding intervention techniques employed had a direct impact on reversing one of the primary neurobiological hallmarks of developmental dyslexia-limited recruitment of left superior temporal gyrus in the face of a phonological challenge.”

A within-subject control task with nondecodable consonant strings showed no change during the study.

“A similar within-subject control task involving nondecodable consonant strings demonstrated no such change over the course of the study, suggesting that the observed changes were specific to decodable letter strings.”

• cites McCandliss et al., 2001Not checked yet

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The intervention yielded decoding gains equal to 1.2 grade levels.

“This intervention produced gains in decoding skills equivalent to 1.2 grade levels of improvement [McCandliss et al., 2003b].”

• cites McCandliss et al., 2003bNot checked yet

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Reading impairment is significantly heritable.

“Another promising line of research capitalizes on the significant heritability of reading impairment [DeFries et al., 1996].”

• cites DeFries et al., 1996Not checked yet

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Left superior temporal gyrus regions were significantly more recruited after the intervention.

“Similar to the results of Simos et al. [2002] reported above, regions of left superior temporal gyrus demonstrated significantly greater recruitment after the intervention.”

• cites McCandliss et al., 2001Not checked yet

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• cites Simos et al., 2002Not checked yet

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SES-related phonological differences are orthogonal to at least one neurobiological phonological influence, planum temporale asymmetry.

“Furthermore, dif-ferences in phonological skill associated with SES have been demonstrated to be orthogonal to at least one neurobiological influence on phonology, degree of asymmetry in planum temporale [Eckert et al., 2001].”

• cites Eckert et al., 2001Not checked yet

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Phonological skill impairment may originate in neurobiological anomalies of the left posterior perisylvian region.

“We have discussed how impairment in phonological skills may be rooted in neurobiological anomalies of the left posterior perisylvian region.”