Cultured Readers: Chinese Kids Show New Neural Side of Dyslexia

Article excerpt

A group of Chinese grade-schoolers with severe reading difficulties has taught scientists an intriguing lesson: Brain disturbances that underlie the inability to read a non-alphabetic script, such as Chinese, differ from those already implicated in the impaired reading of alphabetic systems, such as English.

Neuroscientist Li Tai Han of the National Institute of Mental Health in Bethesda, Md., and his colleagues say their data challenge the view that the reading difficulties considered central to dyslexia spring from a common biological source (SN: 3/31/01, p. 205). "Rather than having a universal origin, the biological abnormality of impaired reading is dependent on culture" the investigators conclude in the Sept. 2 Nature.

Prior brain-imaging studies of dyslexia among readers of letter-based languages have highlighted disturbances in a brain network with its hub in tissue toward the back of the left hemisphere (SN: 5/24/03, p. 324). Scientists have tied that neural region to the ability to match written letters to corresponding sounds.

In Chinese readers with dyslexia, however, the locus of trouble lies in a vertical fold of tissue near the front of the brain. This area assists in recognizing sounds and meanings denoted by Chinese characters and other abstract symbols, Han and his coworkers say.

They studied 16 children, ages 10 to 12, who attended a Beijing elementary school. All the youngsters scored well on intelligence tests, but half of them had severe reading problems.

A functional magnetic resonance imaging (fMRI) scanner measured blood flow throughout each child's brain during two experiments. In one of them, kids judged whether pairs of Chinese characters presented on a computer screen had the same pronunciations. …