Saturday, May 30, 2020
US flag

Cerebellum less involved than thought in dyslexia

New brain imaging research debunks a controversial theory about dyslexia that can impact how it is sometimes treated, Georgetown University Medical Center neuroscientists say.

The cerebellum, a brain structure traditionally considered to be involved in motor function, has been implicated in the reading disability, developmental dyslexia; however, this “cerebellar deficit hypothesis” has always been controversial. The new research shows that the cerebellum is not engaged during reading in typical readers and does not differ in children who have dyslexia.

That is the finding of a new study involving children with and without dyslexia published October 9 in the journal Human Brain Mapping.

It is well established that dyslexia, a common learning disability, involves a weakness in understanding the mapping of sounds in spoken words to their written counterparts, a process that requires phonological awareness. It is also well known that this kind of processing relies on brain regions in the left cortex. However, it has been argued by some that the difficulties in phonological processing that lead to impaired reading originate in the cerebellum, a structure outside (and below the back) of the cortex.

“Prior imaging research on reading in dyslexia had not found much support for this theory called the cerebellar deficit hypothesis of dyslexia, but these studies tended to focus on the cortex,” says the study’s first author, Sikoya Ashburn, a Georgetown PhD candidate in neuroscience. “Therefore, we tackled the question by specifically examining the cerebellum in more detail. We found no signs of cerebellar involvement during reading in skilled readers nor differences in children with reading disability.”

The researchers used functional magnetic resonance imaging to look for brain activation during reading. They also tested for functional connections between the cerebellum and the cortex during reading.

“Functional connectivity occurs when two brain regions behave similarly over time; they operate in sync,” says Ashburn. “However, brain regions in the cortex known to partake in the reading process were not communicating with the cerebellum in children with or without dyslexia while the brain was processing words.”

The results revealed that when reading was not considered in the analysis—that is, when just examining the communications between brain regions at rest—the cerebellum was communicating with the cortex more strongly in the children with dyslexia.

“These differences are consistent with the widely distributed neurobiological alterations that are associated with dyslexia, but not all of them are likely to be causal to the reading difficulties,” Ashburn explains.

“The evidence for the cerebellar deficit theory was never particularly strong, yet people have jumped on the idea and even developed treatment approaches targeting the cerebellum,” says senior author and neuroscientist Guinevere Eden, professor in the Department of Pediatrics at Georgetown University Medical Center and director for its Center for the Study of Learning.

“Standing on a wobble board—one exercise promoted for improving dyslexia that isn’t supported by the evidence—is not going to improve a child’s reading skills. Such treatments are a waste money and take away from other treatment approaches that entail structured intervention for reading difficulties, involving the learning of phonologic and orthographic processing.”

In the long run, these researchers believe the findings can be used to refine models of dyslexia and to assist parents of struggling readers to make informed decisions about which treatment programs to pursue.

More information about dyslexia is available from the International Dyslexia Association or from Understood.org.

Paul Katula is the executive editor of the Voxitatis Research Foundation, which publishes this blog. For more information, see the About page.

Recent posts

Voxitatis congratulates the COVID Class of 2020

2020 is unique and, for high school graduates, different from anything they've seen. Proms, spring sports, & many graduation ceremonies are cancelled. Time for something new.

Vertical addition (m3.nbt.2) math practice

3rd grade, numbers and operations in base 10, 2, 3-digit vertical addition practice problem

Rubber ducks (m3.oa.1) math practice

3rd grade, operational and algebraic thinking, 1, rubber ducky modeling practice problem

Distance learning begins as Covid-19 thrives

What we learn during & from coronavirus, a challenging & imminent crisis, will provide insights into so many aspects of our lives.

Calif. h.s. choir sings with social distancing

Performances with the assistance of technology can spread inspiration across the globe even as the coronavirus spreads illness and disease.

Families plan to stay healthy during closures

Although schools are doing what they can to keep students learning and healthy during the coronavirus outbreak, that duty now shifts to parents.

Illinois temporarily closes all schools

IL schools will be closed on Tuesday, March 17, through at least March 30. Schools in 18 states are now closed due to coronavirus.

Coronavirus closures & cancellations

Many schools are closed and sports tournaments cancelled across America during what the president called a national emergency: coronavirus.

Coronavirus closes schools in Seattle

The coronavirus pandemic has caused colleges to cancel classes, and now Seattle Public Schools became the nation's first large district to cancel classes due to the virus.

Most detailed images ever of the sun

A new telescope at the National Solar Observatory snapped the most detailed pictures of the sun's surface we have ever seen.

Feds boost Bay funding

Restoration efforts in the Chesapeake Bay watershed received a boost in federal funding in the budget Congress passed last month.

LEAVE A REPLY

Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.