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Monday, September 8, 2014

Several Parts of Your Brain Help You Read

From the University of Southern California
via Futurity

By Robert Perkins
August 7, 2013

New research suggests that people who have difficulty reading could benefit from targeted therapies for specific parts of the brain.

The new study, combining brain scans and reading tests, reveals that several regions in the brain are responsible for allowing humans to read.

“Reading is a complex task. No single part of the brain can do all the work,” says Qinghua He, postdoctoral research associate at the University of Southern California Brain and Creativity Institute, and first author of a study on this research that appears in The Journal of Neuroscience.

The study looks at the correlation between reading ability and brain structure revealed by high-resolution magnetic resonance imaging (MRI) scans of more than 200 participants.

To control for external factors, the participants were about the same age and education level (college students); right-handed (lefties use the opposite hemisphere of their brain for reading); and all had about the same language skills (Chinese-speaking, with English as a second language for more than nine years). Their IQ, response speed, and memory were also tested.

The study first collected data for seven different reading tests of a sample of more than 400 participants. These tests were intended to explore three aspects of their reading ability: phonological decoding ability (the ability to sound out printed words); form-sound association (how well participants could make connections between a new word and sound); and naming speed (how quickly participants were able to read out loud).

Each of these aspects, it turned out, was related to the gray matter volume—the amount of neurons—in different parts of the brain.

The MRI analysis showed that phonological decoding ability was strongly connected with gray matter volume in the left superior parietal lobe (around the top/rear of the brain); form-sound association was strongly connected with the hippocampus and cerebellum; and naming speed lit up a variety of locations around the brain.

“Our results strongly suggest that reading consists of unique capacities and is supported by distinct neural systems that are relatively independent of general cognitive abilities,” says Gui Xue, corresponding author of the study. Xue was formerly a research assistant professor at USC and now is a professor and director of the Center for Brain and Learning Sciences at Beijing Normal University.

“Although there is no doubt that reading has to build up existing neural systems due to the short history of written language in human evolution, years of reading experiences might have finely tuned the system to accommodate the specific requirement of a given written system,” Xue says.

Lots of Readers

One of the top features of this study was its unusually wide sample size, according to researchers. Typically, MRI studies test a relatively small sample of individuals—perhaps around 20 to 30—because of the high cost of using the MRI machine. For the current study, the researchers conducted MRI tests on 233 individuals.

Next, the group will explore how to combine data from other factors, such as white matter, resting and task functional MRI, as well as more powerful machine-learning techniques, to improve the accuracy of individuals’ reading abilities.

“Research along this line will enable the early diagnosis of reading difficulties and the development of more targeted therapies,” Xue says.

The team had access to Beijing Normal University’s new MRI center before it opened to the public. The 111 Project of China, the National Science Foundation of China, the Foundation for the Authors of National Excellent Doctoral Dissertations of China, and the National Institute of Health supported the study.

Additional researchers from Beijing Normal University, University of California, Irvine, and Ohio State University contributed to the findings.

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