Different types of spelling problems are associated with dysfunction in different parts of the brain, according to new research by neurologists at Johns Hopkins University. For example, some poor spellers may have problems with long-term memory, while others may have working memory difficulties.
For the study, the researchers analyzed 15 years’ worth of cases in which 33 stroke victims were left with spelling impairments. Some of the patients had long-term memory difficulties, while others had working-memory issues.
“When something goes wrong with spelling, it’s not one thing that always happens — different things can happen and they come from different breakdowns in the brain’s machinery,” said lead author Dr. Brenda Rapp, a professor in the Department of Cognitive Sciences. “Depending on what part breaks, you’ll have different symptoms.”
With long-term memory problems, people can’t remember how to spell words they once knew and tend to make educated guesses. For example, they might correctly guess a predictably spelled word like “camp,” but with a more unpredictable spelling like “sauce,” they might try “soss.” In severe cases of long-term memory, people trying to spell “lion” might offer things like “lonp,” “lint,” and even “tiger.”
With working memory difficulties, however, people know how to spell words but they have trouble choosing the correct letters or putting the letters in the correct order — “lion” might be “lin,” “lino,” or “liont.”
The researchers used computer mapping to chart the brain lesions of each patient and found that in the long-term memory cases, damage appeared on two areas of the left hemisphere, one near the front of the brain and the other at the lower part of the brain towards the back.
In working memory cases, the lesions were primarily found in the left hemisphere but only in the upper part of the brain towards the back.
“I was surprised to see how distant and distinct the brain regions are that support these two subcomponents of the writing process, especially two subcomponents that are so closely inter-related during spelling that some have argued that they shouldn’t be thought of as separate functions,” Rapp said. “You might have thought that they would be closer together and harder to tease apart.”
Though scientists have discovered quite a bit about how the brain handles reading, these findings offer some of the first clear evidence of how it spells, an understanding that could lead to improved behavioral treatments after brain damage as well as more effective ways to teach spelling.
The study findings are published in the journal Brain.
Source: Johns Hopkins University