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Scientists studying the anatomy of children's brains during reading discovered something rather unexpected: Remedial training for poor readers results in a growth of white matter tracts in the brain, and the increase correlates with the level of improvement in sounding out words.
"This is the first evidence for an increase in white matter in response to a remedial behavioral intervention," said lead author Marcel Just, a psychology professor at Carnegie Mellon University in the US, and director of its Centre for Cognitive Brain Imaging. "It provides evidence that repeated cognitive exercises can alter the cortical connectivity of the human brain."
Finding has great potential
The finding could have potential beyond enhancing reading ability. If a behavioural intervention can cause brain growth, benefits might be reflected in any number of brain conditions, including autism, stroke, multiple sclerosis and traumatic brain injury, experts say.
"The evidence is mounting that the brain is wired to fix itself in so many ways," said Dr Thomas Insel, director of the US National Institute of Mental Health. "This study bridges the divide between psychology and biology in showing how the brain responds to a cognitive challenge. We need to make use of this information and figure out ways to treat neurological conditions."
Brain imaging
Collecting and measuring real-time images of the working brain in poor and good readers led Just and his colleagues to identify a decrease in the white matter fibres in the poor readers compared with good readers. The area of interest is in the left frontal lobe, which governs language.
The poor readers received 100 hours of training to improve their reading skills and comprehension.
The remedial intervention actually changed the anatomy of the brain, the researchers reported recently in Neuron.
They conducted brain imaging tests before and after the remediation period on children 8 to 10 years old, including 47 with weak word decoding skills and 25 who had had good reading scores.
Snapshot of the brain's structure
The researchers used a test called diffusion tensor imaging, or DTI, which measures the flow of water through the white matter tracts of the brain. This provides a snapshot of the brain's structure and can be used to compare changes over time.
They found that those with reading problems had decreased microstructural organisation of the white matter in a region of the left frontal lobe.
Most of the poor readers (35 of the 47) received remedial training for six months, and the others, including 12 poor readers, had no reading intervention. At the end of the training period, when the children were rescanned, the scientists found that "the instruction resulted in a change in white matter in the very same region that showed deficiencies in white matter before the intervention," Just said.
Improvements
The changes on the brain scan correlated with improvements on some of the reading measures, he added. Scientists have never before shown that the brain's white matter grows in response to intense but relatively brief remedial training, the team said.
No changes were detected in the white matter in those poor readers who had no remedial intervention. "This suggests that it is not a matter of development but of the intervention itself," Just said.
"I think as the children use these circuits over and over again, the specialised glial cells [called oligodendrocytes] that construct the white matter are building up more myelin [the protective insulation of the white matter fibres] along the axons being fired," Just explained. This makes the neural signal travel 10 times faster and delivers a more precise signal, he said.
Hope for neurological problems
The finding may offer hope for other neurological problems. "There are many worlds to explore," Just said. "It is now obvious that we are not at the mercy of our biology."
The researchers have already begun imaging the brain at work in people with autism and have found a low connectivity in white matter. They plan to provide behavioural interventions and then retest the individuals to look for growth in white matter, which they say would suggest better connectivity between neurons.
Insel expressed enthusiasm for future prospects. "This is a great place to be," he said. "We now have the tools to understand how cognitive strategies alter the biology of the brain." - (Jamie Talan/HealthDay News, March 2010)
