Abstract
The study investigates the relative degree and timing of cortical activation across parietal, temporal, and frontal regions during performance of a continuous visual-word recognition task in children who experience reading difficulties (N = 44, RD) and typical readers (N = 40, NI). Minimum norm estimates of regional neurophysiological activity were obtained from magnetoencephalographic recordings. Children with RD showed bilaterally reduced neurophysiological activity in the superior and middle temporal gyri, and increased activity in rostral middle frontal and ventral occipitotemporal cortices, bilaterally. The temporal profile of activity in the RD group, featured near-simultaneous activity peaks in temporal, inferior parietal, and prefrontal regions, in contrast to a clear temporal progression of activity among these areas in the NI group. These results replicate and extend previous MEG and fMRI results demonstrating atypical, latency-dependent attributes of the brain circuit involved in word reading in children with reading difficulties.
Highlights
Among several explanations of developmental reading difficulties (RD), the presence of a core deficit in the ability to mentally represent and manipulate the sounds of the language appears to account for a significant amount of variance in word-level reading scores, especially during the earlier stages of reading acquisition
Evidence from positron emission tomography (PET) and functional magnetic resonance imaging studies suggested that performance deficits in children with RD is paralleled by hypoactivation in several distinct regions critical for reading ability, including the superior (BA 22) and middle (BA 21) temporal gyri, the inferior parietal lobule [supramarginal and angular gyri (BA 40/39)] and the ventral portion of occipitotemporal cortex
The main effect of Age Group did not reach significance on either measure (p > 0.2), there was a reading by age group interaction on the percentage of hits, F(1,82) = 4.30, p < 0.03, suggesting that age-related differences in response accuracy were larger among RD than non-impaired readers (NI) students
Summary
Among several explanations of developmental reading difficulties (RD), the presence of a core deficit in the ability to mentally represent and manipulate the sounds of the language (phonological awareness) appears to account for a significant amount of variance in word-level reading scores, especially during the earlier stages of reading acquisition. In each individual with RD several alternative or complementary factors may account for such difficulties, the observation that RD is often found in children with intact or even superior intelligence and oral (non-phonological) language skills indicates that RD is associated with functional deficits specific to the brain circuitry that supports reading. Evidence from positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies suggested that performance deficits in children with RD is paralleled by hypoactivation in several distinct regions critical for reading ability, including the superior (BA 22) and middle (BA 21) temporal gyri, the inferior parietal lobule [supramarginal and angular gyri (BA 40/39)] and the ventral portion of occipitotemporal cortex (mainly in the left hemisphere; BA 37; Temple et al, 2001; Shaywitz et al, 2002; Cao et al, 2006; Hoeft et al, 2007; for a recent review and meta-analysis see Maisog et al, 2008). An associated finding of either increased or decreased activation in prefrontal (mainly left inferior frontal, IFG) regions has been reported in these studies
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
