Tag Archive for 'brain'

Visual differences are a consequence, not a cause, of dyslexia

In an article to appear 10 July 2013 in Neuron, Olumide Olulade, Eileen Napoliello, and Guinevere Eden present a series of studies that greatly help educators, psychologists, neurologists, and others understand the relationship between visual deficits and dyslexia. Although most people interested in reading have understood that problems with phonological processes undergird dyslexia, personal accounts of those with dyslexia and some anomalous evidence about the visual cortex and the performance of individuals with dyslexia on certain visual tasks kept the possibility of a visual component open to debate. Professor Eden’s group devised studies and collected the data that shed light on these issues.

In a nutshell, in their first study, Eden’s team found the same results that others had found: When their participants with dyslexia were compared to similar aged children, they showed certain deficits in visual processing associated with a particular part of the brain shown by fMRI. However, when their participants were compared with younger children of like reading ability, there are no deficits in the visual performance; so, these children must not have had the visual problems all along. In their third study, the researchers provided even stronger evidence: The provided powerful remedial reading instruction to their participants and they observed not only improved reading outcomes, but they also found that the students had improved performance on the visual tasks as reflected in fMRI. (Click the accompanying image for a movie of Professors Eden and Olulade explaining the experiments.)

Here is the abstract:

Developmental dyslexia is a reading disorder, yet deficits also manifest in the magnocellular-domi- nated dorsal visual system. Uncertainty about whether visual deficits are causal or consequential to reading disability encumbers accurate identifica- tion and appropriate treatment of this common learning disability. Using fMRI, we demonstrate in typical readers a relationship between reading ability and activity in area V5/MT during visual motion pro- cessing and, as expected, also found lower V5/MT activity for dyslexic children compared to age- matched controls. However, when dyslexics were matched to younger controls on reading ability, no differences emerged, suggesting that weakness in V5/MT may not be causal to dyslexia. To further test for causality, dyslexics underwent a phonolog- ical-based reading intervention. Surprisingly, V5/MT activity increased along with intervention-driven reading gains, demonstrating that activity here is mobilized through reading. Our results provide strong evidence that visual magnocellular dysfunc- tion is not causal to dyslexia but may instead be consequential to impoverished reading.

Olulade, O. A., Napoliello, E. M., & Eden, G. F. (2013). Abnormal visual motion processing is not a cause of dyslexia. Neuron, 79, 1-11. doi:10.1016/j.neuron.2013.05.002

Dyscalculia gets good ink

In the prestigious journal Science, Professors Brian Butterworth, Sashank Varma, and Diana Laurillard published a review article discussing dyscalculia, the Learning Disability that makes arithmetic and mathematics an especially- miserable muddle for some students. In their review they explain why mathematical problems are important to individuals and society, what dyscalculia is, what neuroscientists know about mathematics and dyscalculia, and what they see as the outlook for dyscalculia.
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Procedural learning theory of dyslexia and dysgraphia

In “Dyslexia, Dysgraphia, Procedural Learning and the Cerebellum,” Roderick Nicolson and Angela Fawcett present a fascinating and, to me, strong argument for unifying theoretical views of dyslexia and dysgraphia. To be sure, their analysis is preliminary and basic, but my first read left me feeling as if they’d hit lots of good points. They’ve emphasized impairment of automatic procedural learning in the cerebellum at the level of neural circuits, but in dysgraphia the problems are with motor circuits and in dyslexia they are in the language circuits. In developing their case, they integrate a broad range of neurological and psychological research.

In this review we focus on the developmental disorders of dyslexia (a disorder of reading) and dysgraphia (a disorder of writing), considering their commonalities and differences with a view to reflecting on the theoretical implications. Interest in dysgraphia was stimulated by the distinction between phonological and surface dyslexia (Castles and Coltheart, 1993), which claimed that orthographic problems (spelling) were separable from phonological reading problems. While this distinction has received mixed support ([Snowling et al., 1996] and [Stanovich et al., 1997]) it led to a fruitful analysis not only of the underlying causes of orthographic difficulties, but also to the widespread recognition of developmental difficulties in handwriting control ([Deuel, 1995], [Manis et al., 1996] and Sprenger-Charolles et al., 2000 L. Sprenger-Charolles, P. Cole, P. Lacert and W. Serniclaes, On subtypes of developmental dyslexia: Evidence from processing time and accuracy scores, Canadian Journal of Experimental Psychology-Revue Canadienne De Psychologie Experimentale 54 (2000), pp. 87–104. Abstract | Full Text via CrossRef[Sprenger-Charolles et al., 2000]). The result of this theoretical and empirical progress is that there are two usages of the term dysgraphia. One takes dysgraphia to refer to errors of writing that are analogous to errors in reading (e.g., surface, phonological or deep dysgraphia corresponding to surface, phonological and deep dyslexia), the other relating to difficulties in handwriting control. Furthermore, despite these attempts at differentiation, there remains some controversy in the literature as to whether motor difficulties in handwriting should be subsumed under the label dyslexia.
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LearningRx in the popular press

Sandy Hausman, Charlottesville (VA, US) reporter for WVTF (one of the local public radio stations available in my listening area), carried a story about LearningRx and Learning Disabilities this morning. Unlike the credible coverage provided by many reporters for popular-but-unproven therapies for LD and other disorders, Ms. Hausman provided a sensible and balanced story about LearningRx. Here’s the blurb from WVTF’s Web site

Americans spend millions of dollars keeping our bodies in shape. Now a Charlottesville man is offering a workout for the brain. His center–part of a nationwide franchise–promises to help children and adults improve their concentration, memory, reasoning, and other mental skills. Sandy Hausman has the story.

Unlike many reporters who too-often fall for pop-psych and pop-ed theories (as regularly noted in other posts here on LD Blog), Ms. Hausman gets many facts right (e.g., prevalence of LD), phrases her report carefully (describes LearningRx reports as “internal studies”), includes appropriate caveats along with personal-interest angles, and even incorporates alternative explanations from the experts she interviews.

This is an example of journalism done better. Listen to an MP3 of Ms. Hausman’s report and explore WVTF.org.

Willingham making sense of brain research

In what will be his last guest column for the Washington Post education column, “The Answer Sheet,” cognitive psychologist Dan Willingham advises people to be skeptical about the poppycock that masquerades as scientific advice about brain-based education. Under the headline “Willingham: 3 brain facts every educator should know,” Professor Willingham explains clearly and with the force of evidence and plain, ordinary reason why “most of what you see advertised as educational advice rooted in neuroscience is bunkum.”

Professor Willingham contends that there are three facts educators should know.
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More on smoking and neuropsych disorders

New research shows that using nicotine during pregnancy affects genes involved in myelination and, consequently may help explain why the children of mothers who smoke during pregnancy are more likely to develop such psychiatric disorders as attention deficit hyperactivity disorder, depression, autism, and even drug abuse. In a paper presented at Neuroscience 2010, the annual meeting of the Society for Neuroscience, Professor Ming Li, Ph.D., of the University of Virginia (Charlottesville, VA, US) reported that when rats were given nicotine during pregnancy, their offspring manifested changes in myelin genes for the limbic system, especially the prefrontal cortex, a brain region important for decision-making.

“Our research shows that gestational treatment with nicotine significantly modifies myelin gene expression in specific brain regions that are involved in behavioral processes,” according to Professor Li, leader of the study. “Myelin deficits have been observed in adults with various psychiatric disorders. Our findings suggest that abnormal myelination may contribute to the psychiatric disorders associated with maternal smoking.”
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Letter-sound correspondences: New scanning data

A research team in Professor Leo Blomert’s lab at Maastricht University in the Netherlands reported that brain scans of children with and without dyslexia reveal differences when associating letters with sounds. Vera Blau and colleagues studied 34 9-½-year-old children, 18 of whom were identified as having dyslexia. While the children completed tasks under four different conditions (letters presented only visually; speech sounds presented alone; multi-sensory matching letter–sound pairs; and multi-sensory not-matching letter–sound pairs), the researchers obtained scans of brain activity. They found that in the brains of children with dyslexia there were weaker effects when letters and sounds matched than in the brains of children without dyslexia; these effects appeared most clearly in certain areas of the brain related to language function. In addition, the dyslexic readers’ brains showed weaker activation when speech sounds were the only stimulus (i.e., without accompanying letters).
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Dyslexia in Science

Professor John Gabrieli of the Massachusetts Institute of Technology has a paper in the current issue of Science discussing dyslexia. Here’s the abstract.

Gabrieli, J. D. E. (2009). Dyslexia: A new synergy between education and cognitive neuroscience. Science, 325, 280 – 283

Reading is essential in modern societies, but many children have dyslexia, a difficulty in learning to read. Dyslexia often arises from impaired phonological awareness, the auditory analysis of spoken language that relates the sounds of language to print. Behavioral remediation, especially at a young age, is effective for many, but not all, children. Neuroimaging in children with dyslexia has revealed reduced engagement of the left temporo-parietal cortex for phonological processing of print, altered white-matter connectivity, and functional plasticity associated with effective intervention. Behavioral and brain measures identify infants and young children at risk for dyslexia, and preventive intervention is often effective. A combination of evidence-based teaching practices and cognitive neuroscience measures could prevent dyslexia from occurring in the majority of children who would otherwise develop dyslexia.

Link to the article

LD and chiropracty–NOT

Chiropractors are likely to complain about the treatment that their methods receive in posts on this blog. I’ve posted recently that I find wanting the bases for the the (currently-on-tour, see-’em-in-your-neighborhood-soon) Brain Balance Music program. This post will be even more alarming to supporters of those sorts of treatments for LD.

The fundamental problem with the therapies for Learning Disabilities recommended by some chiropractors is that those therapies are bogus. They may be advocated by people who honestly believe that they’re recommending helpful stuff. The hypothetical relations among the neurological and behavioral factors may sound sensible, but that is, in large part, because we’re listening to the words rather than the facts. The folks may have seen what they believe are legitimate improvements in children’s academic and social behavior after the children received the therapy. Parents may have told them how much better the children seem.

None of that counts as scientific (i.e., objective, generalizable, refutable) evidence of benefits. The advocates may be as seriously misled as they mislead their potential clients. They just don’t have the data. Their explanations are post hoc and untested, at best.

In addition to the probably benign Brain Balance Music methods, consider one of the other chiropractic therapies: Cranio-sacral therapy: The hypothesis is that something about the connection between the child’s head and tail causes learning problems (even mental retardation and autism!) and it can be corrected by chiropractic manipulations.

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Remediation affects brain functioning


Images from CMU Site

As Liz mentioned in a comment on the post RC > WR, Ann Meyler and colleagues at Carnegie Mellon University (CMU) and the Massachusetts Institute of Technology (MIT) published a study documenting changes in children’s brain functioning following remedial reading instruction. In “Modifying the brain activation of poor readers during sentence comprehension with extended remedial instruction: A longitudinal study of neuroplasticity,” Professor Meyler and colleagues reported the results of conducting fMRI examinations of children while they performed sentence comprehension tasks at three different times: (i) prior to remedial reading instruction, (ii) following 100 hours of remedial reading instruction, and (iii) one year after remedial instruction had ended. The team found that the sample of students whom they imaged had clearly different patterns of activity in their brains following remediation and that the differences persisted one year after intervention ended.
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