Brain structure linked to stuttering

Brett Smith for redOrbit.com – Your Universe Online
Stuttering has typically been treated as a psychological or emotional condition, but a new study based on brain scans found that the speech disorder may be linked to irregular white matter in the brain.
Maybe just a crossed wire
Published in the Journal of Speech, Language, and Hearing Research, the new study applied a technique called diffusion spectrum imaging (DSI) in an MRI scanner to analyze the white matter of eight adult stutterers. Researchers uncovered abnormalities of the arcuate fasciculus, one of the pathways that link up the language regions of the brain.
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The arcuate fasciculus attaches at the front end of the brain to the part of the cerebral cortex associated with speech creation. At the rear of the brain, it branches off into three parts.
“What’s interesting is the back half,” said study author Scott Grafton, a brain scientist at the University of California, Santa Barbara. “In the vast majority of the stutterers we scanned, there seems to be a large portion of the connection projecting into the temporal cortex, an area of the brain also critical for speech perception. Seven of eight subjects are missing this third branch of the arcuate fasciculus bundle.”
The study demanded both sensitive imaging, and totally new investigation processes to look at each path in the brain individually and at the individual subject level.
“Big advances have allowed us to reconstruct pathways with greater detail than we were able to do before,” said lead author Matt Cieslak, a graduate student in Grafton’s lab.
“In terms of data, each subject produces what looks like a bowl of spaghetti or a ball of yarn and we had to figure out how to put that data into an analytical framework,” Cieslak explained. “About 40,000 lines of code later we now have a platform for analyzing white matter data, which can be expanded to a large set of subjects.”
Goals for the future
The scientists said their future work would analyze the brains of recovered stutterers to see if white matter actually shifts with a treatment program.
“Is there something special in the wiring of people who recover?” Grafton asked. “Maybe they are missing part of the arcuate fasciculus pathway but they’ve got another one that’s strong enough to pick up the slack. We’d like to be able to investigate that possibility using DSI.”
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“I’m really excited about this work because it’s transforming how we do research in patient groups with very common and challenging developmental disorders that have a great impact on people’s lives but are otherwise largely ignored in neuroscience and by funding agencies,” Grafton continued. “They get diagnosed or described and we throw therapies at them but we don’t really understand the pathophysiologic basis or the biology of these problems.”
“The fact that we can now see big changes in scans of individuals who stutter is huge,” Grafton concluded. “It opens up a lot of opportunities, not just for stutterers but for all kinds of developmental problem like dyslexia, childhood speech apraxia and disorders of coordination.”
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