This article reviews some of our recent functional magnetic resonance imaging (fMRI) studies of
stuttering. Using event-related fMRI experiments, we investigated brain activation during speech production. Results of three studies comparing persons who stutter (PWS) and persons who do not stutter (PWNS) are outlined. Their findings point to a region in the right frontal operculum (RFO) that was consistently implicated in
stuttering. During overt reading and before fluency shaping
therapy, PWS showed higher and more distributed neuronal activation than PWNS. Immediately after
therapy differential activations were even more distributed and left sided. They extended to frontal, temporal, and parietal regions, anterior cingulate, insula, and putamen. These over-activations were slightly reduced and again more right sided two years after
therapy. Left frontal deactivations remained stable over two years of observation, and therefore possibly indicate a dysfunction. After
therapy, we noted higher activations in persons who stutter moderately than in those who stutter severely. These activations might reflect patterns of compensation. We discuss why these findings suggest that fluency-inducing techniques might synchronize a disturbed signal transmission between auditory, speech motor planning, and motor areas.
EDUCATIONAL OBJECTIVES: The reader will learn about and be able to: (1) identify regions of brain activations and deactivations specific for PWS; (2) describe brain activation changes induced by fluency shaping
therapy; and (3) discuss the correlation between
stuttering severity and brain activation.