Researchers have discovered that the brains of stutterers process words differently, even when they're not speaking.They hope their new understanding of this complex disorder will help to reduce the stigma felt by the roughly three million American's who stutter.
While its causes are many, stuttering used to carry with it the stigma of being a "psychological problem." Now, researchers are finding that stutterers' brains process language differently, even when they aren't speaking.
"Stuttering is known to be a very complex disorder, and there has been evidence that language plays an important role in stuttering," explains Christine Weber-Fox, a cognitive neuroscientist at Purdue University. "For example, when children begin stuttering it's not when they're saying their first word, it's when they start combining words, and when language becomes more complex and they're having to formulate more. So we were very interested in knowing the role of language processing in stutterers, even when people who stutter aren't required to speak at all."
Weber-Fox and her team compared the brain activity of 22 adults, half stutterers and half non-stutterers, measuring the activity of brain cells in milliseconds using what looks like a wired-up swimming cap with electrodes that sit on the scalp. The adults were shown two words on a computer screen, and their job was to identifysilently, by pressing a buttonwhich pairs of words rhymed. Some word pairs, like "own" and "gown," were spelled similarly but did not rhyme; some, like "own" and "cone," rhymed but were not spelled similarly, and some, like "own" and "cake," neither rhymed nor were spelled similarly.
"What that forces you to do is say the words to yourself," says Weber-Fox. "In other words if you see the word 'own' flashed on the screen, and then you see the word 'gown' flashed on the screen, you have to as quick as possible say whether they rhyme of not. By doing that we're tapping into some of those same mechanisms that people use when they're trying to formulate speech."
A skullcap with electrodes measures the electrical activity in different parts of the brain.
Weber-Fox found that when the two words looked similar, but didn't rhyme, the stutterers took longer to process the words and answer. "They were overall slower, and just by a little bit, just by a hundredth of a second, but that little bit means a lot when you are talking about brain activity," she says. "The complexity of the task really influenced them or interfered with their processing to a greater extent than it did to people who didn't stutter. The results from the brainwave analysis also showed us that people that stutter maybe performing this task in a different way neurallywe found that their activity over the right hemisphere was greater than the left hemisphere and this is not what we found in our normal speakerstheir responses were more balanced across both hemispheres for this task."
Weber-Fox points out that although language is an important factor in stuttering, there are other factors, including emotion, anxiety and genetics, and its cause can differ for each person and even throughout one's lifespan. She hopes that work like hers will help to remove the stigma of stuttering. "This is involuntary behavior that results from real physiological differences, so I think that that's one thing that's important to keep in mind," she says, adding, "even though it's a physiological response or something that is happening in the brain, that doesn't mean that it's not changeableI think [the research] actually provides a lot of optimism and hope for finding better ways to treat stuttering."