Brain lateralization of phonological awareness varies by maternal education

Socioeconomic status (SES) has been shown to influence language skills, with children of lower SES backgrounds performing worse on language assessments compared to their higher SES peers. While there is abundant behavioral research on the effects of SES, whether there are differences in the neural mechanisms used to support language skill is less established. In this study, we examined the relation between maternal education (ME), a component of SES, and neural mechanisms of language. We focused on Kindergarten children, at the beginning of formal reading education, and on a pre‐reading skill, phonological awareness—the ability to distinguish or manipulate the sounds of language. We determined ME‐related differences in neural activity by examining a skill‐matched sample of typically achieving 5‐year‐old children as they performed a rhyme judgment task. We examined brain lateralization in two language processing regions, the inferior frontal gyrus (IFG) and superior temporal gyrus (STG). In the IFG, lateralization was related to ME but not skill: children with low ME showed bilateral activation compared to children with higher ME who showed leftward lateralization. In the STG, there was a skill by ME interaction on lateralization, such that children with high ME showed a positive relation between rightward lateralization and skill and children with low ME showed a positive relation between leftward lateralization and skill. Thus, we demonstrated ME is related to differences in neural recruitment during language processing, yet this difference in recruitment is not indicative of a deficit in linguistic processing in Kindergarten children.     

Socioeconomic background modulates cognition–achievement relationships in reading

Multiple factors contribute to individual differences in reading ability. The two most thoroughly examined are socioeconomic status (SES) and phonological awareness (PA). Although these factors are often investigated individually, they are rarely considered together. Here we propose that SES systematically influences the relationship between PA and reading ability, and test this prediction in 150 first-graders of varying SES and PA. Results confirm a multiplicative relationship between SES and PA in decoding skills, such that decreased access to resources may amplify cognitive risk factors for poor decoding, whereas greater access to resources may buffer reading skills among children with weaker PA. Attempts to identify the cognitive and experiential factors driving development must acknowledge the complex, synergizing relations between these factors.     

Early language and the development of children's reading skills

There is considerable agreement that vocabulary plays a central role in reading acquisition, but there is less agreement about whether this association is direct or indirect through phonological and print-related knowledge. Longitudinal data from 77 African-American children were analyzed to examine the relationship between language skills, phonological knowledge and print processing skills at pre-kindergarten and kindergarten with reading at pre-kindergarten through second grade. Analyses indicated that home and child care experiences were related to reading indirectly through language and that language and phonological knowledge were both directly related to acquisition of reading skill. This study of African-American children and previous studies of lower- and middle-income children indicate both language and phonological skills play an important role in children becoming successful readers, and that experiences at home and in child care during in early childhood play a role in the acquisition of reading through their enhancement of early language and phonological skills.     

Individual differences in skilled adult readers reveal dissociable patterns of neural activity associated with component processes of reading

We used fMRI to examine patterns of brain activity associated with component processes of visual word recognition and their relationships to individual differences in reading skill. We manipulated both the judgments adults made on written stimuli and the characteristics of the stimuli. Phonological processing led to activation in left inferior frontal and temporal regions whereas semantic processing was associated with bilateral middle frontal activation. Individual differences in reading subskills were reflected in differences in the degree to which cortical regions were engaged during reading. Variation in sight word reading efficiency was associated with degree of activation in visual cortex. Increased phonological decoding skill was associated with greater activation in left temporo-parietal cortex. Greater reading comprehension ability was associated with decreased activation in anterior cingulate and temporal regions. Notably, associations between reading ability and neural activation indicate that brain/behavior relationships among skilled readers differ from patterns associated with dyslexia and reading development.     

Prosodic Awareness Skills and Literacy Acquisition in Spanish

There has been very little research in Spanish on the potential role of prosodic skills in reading and spelling acquisition, which is the subject of the present study. A total of 85 children in 5th year of Primary Education (mean age 10 years and 9 months) performed tests assessing memory, stress awareness, phonological awareness, reading and spelling. In written language tests, errors were classified as phonological (grapheme-to-phoneme conversion rules) or stress-related (placement of the stress mark). Regression analyses showed that, once memory and phonological awareness were controlled, stress awareness partially explained reading and spelling performance as well as error type; however, differences were found between reading and spelling errors. These results show a relationship between prosodic skills--namely stress sensitivity--and the acquisition of reading and spelling skills that seems to be independent of phonological awareness skills.     

Chinese-English biliteracy acquisition: cross-language and writing system transfer

This study investigated cross-language and writing system relationship in biliteracy acquisition of children learning to read two different writing systems-Chinese and English. Forty-six Mandarin-speaking children were tested for their first language (Chinese-L1) and second language (English-L2) reading skills. Comparable experiments in Chinese and English were designed focusing on two reading processes-phonological and orthographic processing. Word reading skills in both writing systems were tested. Results revealed that Chinese onset matching skill was significantly correlated with English onset and rime matching skills. Pinyin, an alphabetic phonetic system used to assist children in learning to read Chinese characters, was highly correlated with English pseudoword reading. Furthermore, Chinese tone processing skill contributed a moderate but significant amount of variance in predicting English pseudoword reading even when English phonemic-level processing skill was taken into consideration. Orthographic processing skill in the two writing systems, on the other hand, did not predict each other's word reading. These findings suggest that bilingual reading acquisition is a joint function of shared phonological processes and orthographic specific skills.     

Home environmental influences on children's language and reading skills in a genetically sensitive design: Are socioeconomic status and home literacy environment environmental mediators and moderators?

This twin study examined how family socioeconomic status (SES) and home literacy environment (HLE) contributes to Chinese language and reading skills. It included 312 Chinese twin pairs aged 3 to 11. Children were individually administered tasks of Chinese word reading, receptive vocabulary and reading‐related cognitive skills, and nonverbal reasoning ability. Information on home environment was collected through parent‐reported questionnaires. Results showed that SES and HLE mediated shared environmental influences but did not moderate genetic influences on general language and reading abilities. Also, SES and HLE mediated shared environmental contributions to receptive vocabulary and syllable and rhyme awareness, but not orthographic skills. The findings of this study add to past twin studies that focused on alphabetic languages, suggesting that these links could be universal across languages. They also extend existing findings on SES and HLE's contributions to reading‐related cognitive skills.     

The neural bases of strategy and skill in sentence-picture verification

This experiment used functional Magnetic Resonance Imaging to examine the relation between individual differences in cognitive skill and the amount of cortical activation engendered by two strategies (linguistic vs. visual-spatial) in a sentence-picture verification task. The verbal strategy produced more activation in language-related cortical regions (e.g., Broca's area), whereas the visual-spatial strategy produced more activation in regions that have been implicated in visual-spatial reasoning (e.g., parietal cortex). These relations were also modulated by individual differences in cognitive skill: Individuals with better verbal skills (as measured by the reading span test) had less activation in Broca's area when they used the verbal strategy. Similarly, individuals with better visual-spatial skills (as measured by the Vandenberg, 1971, mental rotation test) had less activation in the left parietal cortex when they used the visual-spatial strategy. These results indicate that language and visual-spatial processing are supported by partially separable networks of cortical regions and suggests one basis for strategy selection: the minimization of cognitive workload.     

Parental socioeconomic status and the neural basis of arithmetic: differential relations to verbal and visuo‐spatial representations

We examined the relation of parental socioeconomic status (SES) to the neural bases of subtraction in school‐age children (9‐ to 12‐year‐olds). We independently localized brain regions subserving verbal versus visuo‐spatial representations to determine whether the parental SES‐related differences in children's reliance on these neural representations vary as a function of math skill. At higher SES levels, higher skill was associated with greater recruitment of the left temporal cortex, identified by the verbal localizer. At lower SES levels, higher skill was associated with greater recruitment of right parietal cortex, identified by the visuo‐spatial localizer. This suggests that depending on parental SES, children engage different neural systems to solve subtraction problems. Furthermore, SES was related to the activation in the left temporal and frontal cortex during the independent verbal localizer task, but it was not related to activation during the independent visuo‐spatial localizer task. Differences in activation during the verbal localizer task in turn were related to differences in activation during the subtraction task in right parietal cortex. The relation was stronger at lower SES levels. This result suggests that SES‐related differences in the visuo‐spatial regions during subtraction might be based in SES‐related verbal differences.     

Working memory in children with reading disabilities

This study investigated associations between working memory (measured by complex memory tasks) and both reading and mathematics abilities, as well as the possible mediating factors of fluid intelligence, verbal abilities, short-term memory (STM), and phonological awareness, in a sample of 46 6- to 11-year-olds with reading disabilities. As a whole, the sample was characterized by deficits in complex memory and visuospatial STM and by low IQ scores; language, phonological STM, and phonological awareness abilities fell in the low average range. Severity of reading difficulties within the sample was significantly associated with complex memory, language, and phonological awareness abilities, whereas poor mathematics abilities were linked with complex memory, phonological STM, and phonological awareness scores. These findings suggest that working memory skills indexed by complex memory tasks represent an important constraint on the acquisition of skill and knowledge in reading and mathematics. Possible mechanisms for the contribution of working memory to learning, and the implications for educational practice, are considered.     

Home literacy activities and their influence on early literacy skills.

The relationship between the home environments of 66 children and their language and literacy development was examined. After accounting for child age, parent education, and child ability as indexed by scores on a rapid automatized naming task and Block Design of the WPPSI-R, shared book reading at home made no contribution to the prediction of the literacy skills of letter name and letter sound knowledge in kindergarten. In contrast, home activities involving letters predicted modest and statistically significant amounts of variance. For the areas of receptive vocabulary and phonological sensitivity, neither shared book reading nor letter activities were predictive. Follow-up to mid-Grade 2 underscored the importance of letter name/sound knowledge and phonological sensitivity in kindergarten in accounting for individual differences in later achievement in reading comprehension, phonological spelling, and conventional spelling.     

Is there an alternative cerebral network associated with enhanced phonological processing in deaf speech-users? An exceptional case

Most people born deaf and exposed to oral language show scant evidence of sensitivity to the phonology of speech when processing written language. In this respect they differ from hearing people. However, occasionally, a prelingually deaf person can achieve good processing of written language in terms of phonological sensitivity and awareness, and in this respect appears exceptional. We report the pattern of event-related fMRI activation in such a deaf reader while performing a rhyme-judgment on written words with similar spelling endings that do not provide rhyme clues. The left inferior frontal gyrus pars opercularis and the left inferior parietal lobe showed greater activation for this task than for a letter-string identity matching task. This participant was special in this regard, showing significantly greater activation in these regions than a group of hearing participants with a similar level of phonological and reading skill. In addition, SR showed activation in the left mid-fusiform gyrus; a region which did not show task-specific activation in the other respondents. The pattern of activation in this exceptional deaf reader was also unique compared with three deaf readers who showed limited phonological processing. We discuss the possibility that this pattern of activation may be critical in relation to phonological decoding of the written word in good deaf readers whose phonological reading skills are indistinguishable from those of hearing readers.     

Neural correlates of socioeconomic status in the developing human brain

Socioeconomic disparities in childhood are associated with remarkable differences in cognitive and socio-emotional development during a time when dramatic changes are occurring in the brain. Yet, the neurobiological pathways through which socioeconomic status (SES) shapes development remain poorly understood. Behavioral evidence suggests that language, memory, social-emotional processing, and cognitive control exhibit relatively large differences across SES. Here we investigated whether volumetric differences could be observed across SES in several neural regions that support these skills. In a sample of 60 socioeconomically diverse children, highly significant SES differences in regional brain volume were observed in the hippocampus and the amygdala. In addition, SES × age interactions were observed in the left superior temporal gyrus and left inferior frontal gyrus, suggesting increasing SES differences with age in these regions. These results were not explained by differences in gender, race or IQ. Likely mechanisms include differences in the home linguistic environment and exposure to stress, which may serve as targets for intervention at a time of high neural plasticity.     

Musical rhythm discrimination explains individual differences in grammar skills in children

This study considered a relation between rhythm perception skills and individual differences in phonological awareness and grammar abilities, which are two language skills crucial for academic achievement. Twenty‐five typically developing 6‐year‐old children were given standardized assessments of rhythm perception, phonological awareness, morpho‐syntactic competence, and non‐verbal cognitive ability. Rhythm perception accounted for 48% of the variance in morpho‐syntactic competence after controlling for non‐verbal IQ, socioeconomic status, and prior musical activities. Children with higher phonological awareness scores were better able to discriminate complex rhythms than children with lower scores, but not after controlling for IQ. This study is the first to show a relation between rhythm perception skills and morpho‐syntactic production in children with typical language development. These findings extend the literature showing substantial overlap of neurocognitive resources for processing music and language. A video abstract of this article can be viewed at: http://youtu.be/_lO692qHDNg     

Oral language and code-related precursors to reading: evidence from a longitudinal structural model

This study examined code-related and oral language precursors to reading in a longitudinal study of 626 children from preschool through 4th grade. Code-related precursors, including print concepts and phonological awareness, and oral language were assessed in preschool and kindergarten. Reading accuracy and reading comprehension skills were examined in 1st through 4th grades. Results demonstrated that (a) the relationship between code-related precursors and oral language is strong during preschool; (b) there is a high degree of continuity over time of both code-related and oral language abilities; (c) during early elementary school, reading ability is predominantly determined by the level of print knowledge and phonological awareness a child brings from kindergarten; and (d) in later elementary school, reading accuracy and reading comprehension appear to be 2 separate abilities that are influenced by different sets of skills.     

The Neural Bases of Strategy and Skill in Sentence–Picture Verification

This experiment used functional Magnetic Resonance Imaging to examine the relation between individual differences in cognitive skill and the amount of cortical activation engendered by two strategies (linguistic vs. visual–spatial) in a sentence–picture verification task. The verbal strategy produced more activation in language-related cortical regions (e.g., Broca's area), whereas the visual–spatial strategy produced more activation in regions that have been implicated in visual–spatial reasoning (e.g., parietal cortex). These relations were also modulated by individual differences in cognitive skill: Individuals with better verbal skills (as measured by the reading span test) had less activation in Broca's area when they used the verbal strategy. Similarly, individuals with better visual–spatial skills (as measured by the Vandenberg, 1971, mental rotation test) had less activation in the left parietal cortex when they used the visual-spatial strategy. These results indicate that language and visual–spatial processing are supported by partially separable networks of cortical regions and suggests one basis for strategy selection: the minimization of cognitive workload.     

Language deficits in dyslexic children: speech perception, phonology, and morphology

We investigated the relationship between dyslexia and three aspects of language: speech perception, phonology, and morphology. Reading and language tasks were administered to dyslexics aged 8-9 years and to two normal reader groups (age-matched and reading-level matched). Three dyslexic groups were identified: phonological dyslexics (PD), developmentally language impaired (LI), and globally delayed (delay-type dyslexics). The LI and PD groups exhibited similar patterns of reading impairment, attributed to low phonological skills. However, only the LI group showed clear speech perception deficits, suggesting that such deficits affect only a subset of dyslexics. Results also indicated phonological impairments in children whose speech perception was normal. Both the LI and the PD groups showed inflectional morphology difficulties, with the impairment being more severe in the LI group. The delay group's reading and language skills closely matched those of younger normal readers, suggesting these children had a general delay in reading and language skills, rather than a specific phonological impairment. The results are discussed in terms of models of word recognition and dyslexia.     

Is there a causal link from phonological awareness to success in learning to read?

In this review, we re-assess the evidence that phonological awareness represents a skill specific to spoken language that precedes and directly influences the process of reading acquisition. Longitudinal and experimental training studies are examined in detail, as these are considered most appropriate for exploring a causal hypothesis of this nature. A particular focus of our analysis is the degree to which studies to date have controlled for existing literacy skills in their participants and the influence that these skills might have on performance on phonological awareness tasks. We conclude that no study has provided unequivocal evidence that there is a causal link from competence in phonological awareness to success in reading and spelling acquisition. However, we believe that such a study is possible and outline some ideas for its design and implementation.     

Individual differences in neural mechanisms of selective auditory attention in preschoolers from lower socioeconomic status backgrounds: an event‐related potentials study

Selective attention, the ability to enhance the processing of particular input while suppressing the information from other concurrent sources, has been postulated to be a foundational skill for learning and academic achievement. The neural mechanisms of this foundational ability are both vulnerable and enhanceable in children from lower socioeconomic status (SES) families. In the current study, we assessed individual differences in neural mechanisms of this malleable brain function in children from lower SES families. Specifically, we investigated the extent to which individual differences in neural mechanisms of selective auditory attention accounted for variability in nonverbal cognitive abilities in lower SES preschoolers. We recorded event‐related potentials (ERPs) during a dichotic listening task and administered nonverbal IQ tasks to 124 lower SES children (77 females) between the ages of 40 and 67 months. The attention effect, i.e., the difference in ERP mean amplitudes elicited by identical probes embedded in stories when attended versus unattended, was significantly correlated with nonverbal IQ scores. Larger, more positive attention effects over the anterior and central electrode locations were associated with superior nonverbal IQ performance. Our findings provide initial evidence for prominent individual differences in neural indices of selective attention in lower SES children. Furthermore, our results indicate a noteworthy relationship between neural mechanisms of selective attention and nonverbal IQ performance in lower SES preschoolers. These findings provide the basis for future research to identify the factors that contribute to such individual differences in neural mechanisms of selective attention.