A team of researchers who study reading and neuropsychology has reported results from a study that show what parts of the brain are involved in sentence comprehension other than those used for recognizing the words in the sentences. In a study entitled “Functional MRI of Sentence Comprehension in Children with Dyslexia: Beyond Word Recognition” that will appear soon in Cerebral Cortex, S. L. Rimrodt and colleagues (including Ken Pugh and Laurie Cutting, whom I know) compared the fMRI data from groups of children with and without dyslexia on tasks involving word reading and sentence comprehension. They found that the children with dyslexia had disproportional activation of areas of the brain usually employed in processing linguistic information, attending, and selecting responses.
Here’s the abstract:
Sentence comprehension (SC) studies in typical and impaired readers suggest that reading for meaning involves more extensive brain activation than reading isolated words. Thus far, no reading disability/dyslexia (RD) studies have directly controlled for the word recognition (WR) components of SC tasks, which is central for understanding comprehension processes beyond WR. This experiment compared SC to WR in 29, 9–14 year olds (15 typical and 14 impaired readers). The SC-WR contrast for each group showed activation in left inferior frontal and extrastriate regions, but the RD group showed significantly more activation than Controls in areas associated with linguistic processing (left middle/superior temporal gyri), and attention and response selection (bilateral insula, right cingulate gyrus, right superior frontal gyrus, and right parietal lobe). Further analyses revealed this overactivation was driven by the RD group’s response to incongruous sentences. Correlations with out-of-scanner measures showed that better word- and text-level reading fluency was associated with greater left occipitotemporal activation, whereas worse performance on WR, fluency, and comprehension (reading and oral) were associated with greater right hemisphere activation in a variety of areas, including supramarginal and superior temporal gyri. Results provide initial foundations for understanding the neurobiological correlates of higher-level processes associated with reading comprehension.
Rimrodt, S. L., Clements-Stephens, A. M., Pugh, K. R., Courtney, S. M., Gaur, P., Pekar, J. J., & Cutting, L. E. (2008, May 30). Functional MRI of Sentence Comprehension in Children with Dyslexia: Beyond Word Recognition. Cereb Cortex. doi:10.1093/cercor/bhn092
I’m impressed with the reasoning and the scientific qualities of this study. It’s valuable for its contribution to our fundamental understanding of what’s happening in brains. For understanding sentences, word recognition appears to be a necessary-but-not-sufficient competence.
As Dan Willingham and I have argued, these sorts of results are not likely to have a substantial effect on the teaching of reading, but they do help us begin to understand the neurobiological characteristics of dyslexia. To those who take results such as these to be an indication of the bio-neurological reality of dyslexia: I agree. But, please don’t leap from the idea that these indicators of bio-neurological reality to causal statements; these sorts of data tell us that there is a relationship between dyslexia, but, at the fundamental level, they don’t tell us whether the neuropsych performance is cause or consequence of dyslexia.
Willingham, D. T., & Lloyd, J. W. (2007). How educational theories can use neuroscientific data. Mind, Brain, & Education, 1, 140-149.
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I missed this one:
doi:10.1016/j.neuropsychologia.2008.03.012
Modifying the brain activation of poor readers during sentence comprehension with extended remedial instruction: A longitudinal study of neuroplasticity
Ann Meylera, Timothy A. Kellera, Vladimir L. Cherkasskya, John D.E. Gabrielib and Marcel Adam Justa, Corresponding Author Contact Information, E-mail The Corresponding Author
Abstract
This study used fMRI to longitudinally assess the impact of intensive remedial instruction on cortical activation among 5th grade poor readers during a sentence comprehension task. The children were tested at three time points: prior to remediation, after 100 h of intensive instruction, and 1 year after the instruction had ended. Changes in brain activation were also measured among 5th grade good readers at the same time points for comparison. The central finding was that prior to instruction, the poor readers had significantly less activation than good readers bilaterally in the parietal cortex. Immediately after instruction, poor readers made substantial gains in reading ability, and demonstrated significantly increased activation in the left angular gyrus and the left superior parietal lobule. Activation in these regions continued to increase among poor readers 1 year post-remediation, resulting in a normalization of the activation. These results are interpreted as reflecting changes in the processes involved in word-level and sentence-level assembly. Areas of overactivation were also found among poor readers in the medial frontal cortex, possibly indicating a more effortful and attentionally guided reading strategy.
The press release from Carnegie Mellon:
Carnegie Mellon researchers say poor readers initially have less activation in the parietotemporal area of the brain, which is the region responsible for decoding the sounds of written language and assembling them into words and phrases that make up a sentence, than do good readers. However, remedial instruction increases the struggling readers’ activation to near normal levels.
This also was the first brain imaging study in which children were tested on their understanding of the meanings of sentences, not just on their recognition of single words.
“This study demonstrates how the plasticity of the human brain can work for the benefit of remedial learning,” says neuroscientist Marcel Just, director of Carnegie Mellon’s Center for Cognitive Brain Imaging (CCBI), and senior author of the new study currently available on the Web site of the journal Neuropsychologia. “We are at the beginning of a new era of neuro-education.”
The poor readers worked in groups of three for an hour a day with a reading “personal trainer,” a teacher specialized in administering a remedial reading program. The training included both word decoding exercises in which students were asked to recognize the word in its written form and tasks in using reading comprehension strategies. The poor readers were 25 fifth-graders taken from a stratified sample from schools in Allegheny County, which is home to Pittsburgh and a number of its surrounding municipalities.
Using functional magnetic resonance imaging (fMRI), CCBI Research Fellows Ann Meyler and Tim Keller measured blood flow to all of the different parts of the brain while children were reading and found that that the parietotemporal areas were significantly less activated among the poor readers than in the control group. The sound-based representation that is constructed in the parietal areas is then processed for the meanings of the words and the structure of the sentence, activating other brain areas.
The sentences were relatively straightforward ones, which the children judged as being sensible or nonsense, such as “The girl closed the gate” and “The man fed the dress.” The children’s accurate sensibility judgments ensured that they were actually processing the meaning of the sentences, and not just recognizing the individual words.
Further, the activation increases in the previously underactivating areas remained evident well after the intensive instruction had ended. When the children’s brains were scanned one year after instruction, their neural gains were not only maintained but became more solidified.
“With the right kind of intensive instruction, the brain can begin to permanently rewire itself and overcome reading deficits, even if it can’t entirely eliminate them,” Just said.
These findings of initial parietotemporal underactivation among poor readers provide evidence against a common misconception about dyslexia. There is a persistent but incorrect belief that dyslexia is primarily caused by difficulties in the visual perception of letters, leading to confusions between letters like “p” and “d”. However, such visual difficulties are the cause of dyslexia in only about 10 percent of the cases. The most common cause, accounting for more than 70 percent of dyslexia, is a difficulty in relating the visual form of a letter to its sound, which is not a straightforward process in the English language. The same parietotemporal areas of the brain that showed increased activation following instruction are centrally involved in this sound-based processing.
The findings also give hope to using the marvels of brain plasticity for instructional purposes in “new” (for the brain) subject areas. “The human brain did not evolve to process written language, which is a cultural invention dating back only 5000 years,” Just said. “Some people’s brains happen to be less proficient at relating written symbols to the sounds of language, and they need focused instruction to get those areas up to an adequate level of performance.” Other skills that may be valuable as newer technologies (than written language) arise should also be amenable to neuroinstruction.
“Any kind of education is a matter of training the brain. When poor readers are learning to read, a particular brain area is not performing as well as it might, and remedial instruction helps to shape that area up,” Just said. “This finding shows that poor readers can be helped to develop buff brains. A similar approach should apply to other skills.”