Chinese- and English-speaking dyslexics have different neurological deficits, according to a study released Monday which suggests that dyslexia may be different brain disorders in the two cultures.
English speakers with the reading disability typically have
functional abnormalities in posterior parts of the brain associated
with reading and possibly less gray matter in these areas also.
In Chinese dyslexics, on the other hand, the functional and
structural brain abnormalities related to reading correspond with the
left middle frontal region of the brain, according to new research.
The new research is based on brain scans performed on 16 dyslexic
Chinese speakers and 16 of their peers with normal reading ability
during the course of a couple of tests.
How the study was conducted
Researchers first asked the 32 Beijing primary school students to
look at two Chinese characters in different size font to see if they
could identify the difference in size.
Having used this question to establish which part of their brains
was involved with reading, the investigators then presented the
students with two more Chinese characters and asked them if the two
The second question was designed to test the students' phonological
awareness, their sensitivity to the sound structure of language, which
is considered an important and reliable predictor of reading ability.
The scans revealed that the students with the reading disability had
less activity in the left middle frontal gyrus on the second task than
the children without the disability.
They also had less gray matter in this brain region than the
children with normal reading skills.
Differs from English dyslexics
Further, the Chinese dyslexic children did not have any
abnormalities in the parts of the brain that have been shown to be
problematic in alphabetic-language dyslexics.
While surprising, the contrast can be explained by the fact that the
Chinese language uses characters, while English uses a letter alphabet, one of the researchers said.
"At the functional level, it's easy to understand why Chinese and
English speakers use different parts of the brain to read language,"
said Li-Hai Tan, a professor of linguistics and neuroscience at the
University of Hong Kong, and author on the paper.
"The different brain networks accommodate the different features of
English and Chinese. The two systems are dramatically different.
Chinese is pictographic and English is more phonological, or
However, he said that it was striking that the Chinese dyslexic
children had less gray matter in the middle frontal gyrus, and that was
probably a function of genetics, since this phenomenon is thought to be
This would suggest that the genetic makeup of Chinese speaking
dyslexics is different from that of English speakers with the same
disorder since they have reductions of gray matter in different sites
of the brain.
The study involved researchers from the University of Hong Kong, the
Beijing Institute of Technology, and the University of Pittsburgh and
appears in the journal Proceedings of the National Academy of Sciences. – (Sapa-AFP)