Résumé :
Developmental stuttering affects about 5% of children and 1% of adults. Fluency can be enhanced in people who stutter by altering sensory feedback during speech production and by altering production e.g. by whispering, changing pitch or accent, or by external cueing, speaking in unison or singing. Abnormal sensorimotor integration and impairment in cortico-striatal-thalamo-cortical circuits might explain the occurrence and persistence of speech disfluency. Brain imaging studies show some support for these theories. I will present our early structural and functional brain imaging studies that revealed abnormal white matter microstructure underlying cortical differences in brain activity during speech. In recent work, we found increased amounts of iron in the striatum in a large sample of people who stutter. We have also used brain stimulation to enhance speech fluency in people who stutter. Five days of stimulation paired with fluency training increased fluency and brain activity in the striatum compared with fluency training alone. Finally, I will present our findings from imaging the vocal tract during speech production that indicate instability in the speech motor system in people who stutter during perceptibly fluent speech.
