A region of the brain thought to control speech production develops abnormally in children who stutter--a pattern that persists into adulthood, according to new University of Alberta (Canada) research. In the first study to use MRI imaging to examine brain development in both children and adults who stutter, researchers at the U of A's Institute for Stuttering Treatment and Research (ISTAR) found abnormal development of grey matter in Broca's area, the region of the frontal lobe responsible for speech. It was the only abnormality found in the 30 regions of the brain the research team investigated. "In every other region of the brain we studied, we saw a typical pattern of brain matter development. These findings implicate Broca's area as a crucial region associated with stuttering," said Dr. Deryk Beal, ISTAR executive director and an assistant professor in the Faculty of Rehabilitation Medicine. Dr. Beal's team, which included collaborators from the University of Toronto, studied MRI images of the brains of 116 males between the ages of six and 48 years--both the largest group and widest age range –ever --for such a study. Roughly half the participants stuttered; the rest served as a control group. The research team observed a steady, and expected, decline in the cortical thickness of grey matter in the control group--a decline not observed in people who stutter. This decline in thickness, Dr. Beal explained, is actually a good thing because it reflects how the brain gets more efficient as we age, requiring fewer neural resources. "One interpretation of this finding could be that this area, in people who stutter, does not operate as efficiently within the brain network for speech production," Dr. Beal said.
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