This study aimed to examine early specialization of brain regions for phonological and semantic processing of spoken language in young children. Thirty‐five typically developing children aged from 5 to 6 years performed auditory phonological (same sound judgment) and semantic (related meaning judgment) word‐level tasks. Using functional magnetic resonance imaging, we examined specialization within the language network, by conducting three levels of analysis. First, we directly compared activation between tasks and found a greater sound judgment as compared to meaning judgment activation in left superior temporal gyrus (STG) and supramarginal gyrus. In contrast, greater meaning judgment as compared to sound judgment task activation was found in left middle temporal gyrus (MTG). Second, we examined the brain‐behavior correlations and found that phonological skill was correlated with the task difference in activation in left superior temporal sulcus, whereas semantic skill was correlated with the task difference in activation in left MTG. Third, we compared between two experimental conditions within each task and found a parametric effect in left STG for the sound judgment task, and a parametric effect in left MTG for the meaning judgment task. The results of this study indicate that, by the age of 5–6 years, typically developing children already show some specialization of temporo‐parietal brain regions for phonological and semantic processes. However, there were no task differences in the left inferior frontal gyrus suggesting that the frontal cortex may not yet be specialized in this age range, which is consistent with the delayed maturation of the frontal cortex.
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.
more » « less- NSF-PAR ID:
- 10087787
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Developmental Science
- Volume:
- 22
- Issue:
- 6
- ISSN:
- 1363-755X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Children with dyslexia frequently also struggle with math. However, studies of reading disability (RD) rarely assess math skill, and the neurocognitive mechanisms underlying co‐occurring reading and math disability (RD+MD) are not clear. The current study aimed to identify behavioral and neurocognitive factors associated with co‐occurring MD among 86 children with RD. Within this sample, 43% had co‐occurring RD+MD and 22% demonstrated a possible vulnerability in math, while 35% had no math difficulties (RD‐Only). We investigated whether RD‐Only and RD+MD students differed behaviorally in their phonological awareness, reading skills, or executive functions, as well as in the brain mechanisms underlying word reading and visuospatial working memory using functional magnetic resonance imaging (fMRI). The RD+MD group did not differ from RD‐Only on behavioral or brain measures of phonological awareness related to speech or print. However, the RD+MD group demonstrated significantly worse working memory and processing speed performance than the RD‐Only group. The RD+MD group also exhibited reduced brain activations for visuospatial working memory relative to RD‐Only. Exploratory brain‐behavior correlations along a broad spectrum of math ability revealed that stronger math skills were associated with greater activation in bilateral visual cortex. These converging neuro‐behavioral findings suggest that poor executive functions in general, including differences in visuospatial working memory, are specifically associated with co‐occurring MD in the context of RD.
Research Highlights Children with reading disabilities (RD) frequently have a co‐occurring math disability (MD), but the mechanisms behind this high comorbidity are not well understood.
We examined differences in phonological awareness, reading skills, and executive function between children with RD only versus co‐occurring RD+MD using behavioral and fMRI measures.
Children with RD only versus RD+MD did not differ in their phonological processing, either behaviorally or in the brain.
RD+MD was associated with additional behavioral difficulties in working memory, and reduced visual cortex activation during a visuospatial working memory task.
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