Research Update: Learning Disabilities

October 1, 2008
Study First to Examine Sentence Comprehension While Controlling for Word Recognition

New Reading Disabilities Study Uses Fmri Technology To Examine Sentence Comprehension In Adolescents

Study First to Examine Sentence Comprehension While Controlling for Word Recognition

A new study published in Cerebral Cortex uses functional brain imaging to examine the brains of children with and without reading disabilities while they read for comprehension. It is the first published study using functional magnetic resonance imaging (fMRI) to compare brain activity associated with sentence comprehension while controlling for word recognition between children with reading disabilities (RD) and typical readers. Laurie E. Cutting, Ph.D., Sheryl Rimrodt, M.D., and their colleagues at the Kennedy Krieger Institute in Baltimore, Md. analyzed the brain activity of adolescents when comprehending sentences. This is a vital area of investigation because sentence comprehension becomes a critical aspect of reading as children move into fourth grade and are required to not just recognize words, but learn from the text they are reading. The study revealed that more brain activity was required for sentence comprehension in the RD group and found that increased activation in specific regions of the brain contributes to poorer performance on reading and language measures.

Word recognition, or the ability to recognize and decode words accurately and efficiently, is a defining characteristic of reading disabilities (dyslexia) and affects a child's ability to comprehend sentences. While previous research has identified brain activity associated with word recognition, few studies have focused on brain activity contributing to the ability to comprehend sentences, specifically in older children with reading disabilities. To examine the brain activity associated with sentence comprehension, the current study compared sentence comprehension (SC) to word recognition (WR) in 29 9-14 year olds (15 typical readers and 14 impaired readers). In the SC task, participants decided whether sentences were meaningful or non-meaningful (i.e. contained semantic and syntactic errors). During the WR task, participants were shown a set of words in order to indicate when they saw a word for the first time and when a word was repeated.

Overall, the RD group showed much more widespread brain activity than the control group, who used a more tightly coordinated, less diffuse network of areas associated with language processing when performing tasks. The RD group showed significantly more brain activity in left hemisphere regions of the brain associated with processing language as well as right hemisphere regions associated with attention and response selection. Further analyses revealed that this over-activation was caused by the RD group's response when attempting to detect non-meaningful sentences. Correlation with out-of-scanner behavioral measures showed that better word and text level reading fluency was associated with greater activity in the left hemisphere, while word recognition, fluency and comprehension were associated with greater right hemisphere comprehension.

This study is an important contribution to the understanding of how higher-level language processing impacts reading comprehension, especially for children with reading disabilities. These results provide an initial foundation for both researchers and educators on the brain basis of processes associated with reading comprehension in an age group that consistently uses this skill in school.