Dyslexia Varies by Writing System, Brain Scans Show

With 6,000 characters to memorize, Westerners shudder at the idea of reading even the most basic street signs and instructions in Chinese.

A new set of brain images shows why: Reading English-style alphabets and Chinese characters use very different parts of the brain.

The results, published in the latest issue of the journal Nature, also suggest that Chinese schoolchildren with reading problems misfire in a different brain region than the one used in reading alphabet-based languages such as English.

This demonstrates that the learning disorder dyslexia is not the same in every culture and does not have a universal biological cause, researchers said.

Dyslexia is a developmental disorder in which people of normal intelligence have difficulty learning to read, spell and master other language skills. In the United States, it is observed in 5% to 15% of the population, while in China it affects up to 7%.

Brain scans show that English-reading dyslexics misfire in the left temporal-parietal region of the brain associated with awareness of phonemes.

According to the study, reading Chinese uses the left middle frontal gyrus, or LMFG, which is associated with symbol interpretation.

Unlike alphabet letters, Chinese characters represent entire thoughts and physical objects.

Brain scans show the LMFG fires in normal Chinese readers, but Chinese dyslexics show glitches in that circuitry, according to Li-Hai Tan of the National Institute of Mental Health in Bethesda, Md., and the University of Hong Kong.

The finding does not mean Chinese dyslexics might be able to use different portions of their brain to read English more easily.

Once a person learns to read he or she tends to use the same circuitry regardless of the second language and its alphabet.