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13 Sep 2004 08:34
Reading difficulties can be traced to different parts of the brain in Chinese and Western children, a team of American scientists say.
In China, dyslexia appears to have a different physical origin, because the script, also used in Japan, is symbol rather than alphabet-based.
The discovery casts doubt on the widespread assumption that dyslexia has a universal cause.
Instead, researchers believe it is heavily influenced by culture.
The findings also support the idea that therapy strategies for treating dyslexia can “tune” the brain.
This fits in with the theory that the brain can to some extent be physically shaped by cultural differences.
A team of scientists led by Li Hai Tan, from the National Institute of Mental Health in Bethesda, Maryland, scanned the brains of 16 dyslexic Chinese children as they performed various language-based tasks.
The tasks involved understanding Chinese symbols, for instance by judging whether two characters had the same pronunciation.
The tests showed that reading difficulties in the children, whose average age was 11, were linked to functional problems in a brain region called the left middle frontal gyrus (LMFG).
Other researchers, studying Western children, had previously connected dyslexia to a different region, the left tempoparietal.
The LMFG acts as a “centre for fluent Chinese reading” by integrating information about written characters in verbal and spatial memory, the scientists reported in the journal Nature.
They wrote: “The LMFG is crucial to normal Chinese reading, as its dysfunction is associated with Chinese reading difficulty.
“Our findings support the idea that cognitive strategies for reading development tune the cortex. This idea draws a parallel with a recent proposal that anatomical brain differences can be produced by differences in cultures.”
Studies of brain anatomy had found that the LMFG region was larger in Chinese-speaking Asians than in English-speaking Caucasians.
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