Controle oromotor (sujeito gago) A ativação na área responsável pelo controle dos músculos da fala (a área motora primária) teve igual intensidade em ambos os lados do cérebro. Na fala normal, a atividade foi mais forte no lado esquerdo. Isto sugere que os gagos não desenvolveram uma especialização lateral do controle da fala, que é o padrão verificado em 95% dos sujeitos com fala normal. disfluente normal

Speech preparation (non-stutterer) Speech-motor programming (creation of speech plans) is done in the inferior pre-motor area. It is very important for normal speech. This is active on both sides of the brain, but more so on the left. stutterer non-stutterer

Speech preparation (stutterer) Activation in the inferior pre-motor area (the brain’s speech-programming unit) was essentially identical in stutterers and non-stutterers. This surprising similarity helps eliminate this area as a culprit in stuttering. speech preparation stutterer non-stutterer movement preparation movement release mouth movement movement coordination hearing (yourself speak)

Movement preparation (non-stutterer) Brain programs for body movements are created in the superior pre-motor area. This area is minimally involved in normal speech production. Notice the small, low-intensity activation on the left side of the brain (for non-stuttered speech). This area is important because it is overactive in stutterers. stutterer non-stutterer

Movement preparation (stutterer) Hyperactivity in the superior pre-motor cortex (a movement programming area) was seen during stuttered speech but not during non-stuttered speech. Notice also that this activity is on the right side, while normal speech-related brain activity is on the left side. These differences from normal speech are important clues to the cause of stuttering. speech preparation stutterer non-stutterer movement preparation movement release mouth movement movement coordination hearing (yourself speak)

Movement release (non-stutterer) This area, called the supplementary motor area, triggers the release (the start) of motor programs. It is important for precise timing of speech and other complex movements. In non-stuttered speech, activation in this area is relatively small, weak (dim) and chiefly on the left side. stutterer non-stutterer

Movement release (stutterer) The supplementary motor area (involved in motor-program release) was very overactive and switched sides during stuttered speech. Notice that the activity is larger, more intense (brighter) and more on the right side than in non-stuttered speech. This is interpreted as meaning that stuttering is an interruption of speech-motor programs, which this area must repeatedly restart. speech preparation stutterer non-stutterer movement preparation movement release mouth movement movement coordination hearing (yourself speak)

Mouth movement (non-stutterer) Having been programmed by the inferior pre-motor area (speech preparation) and triggered by the supplementary motor area (movement release), this area (the primary-motor mouth area) directly controls the muscular movements of speech. In non-stutterers, the activations are stronger on the left side of the brain. stutterer non-stutterer

Mouth movement (stutterer) Activation in the area responsible for controlling speech muscles (the primary motor area) was equal on both sides of the brain. In non-stuttered speech, activity was stronger on the left. This suggests that stutterers fail to develop left-brain control of speech, which is the pattern in about 95% of non-stutterers. speech preparation stutterer non-stutterer movement preparation movement release mouth movement movement coordination hearing (yourself speak)

Movement coordination (non-stutterer) The cerebellum uses sensory feedback to help guide and smooth complex movements. In speech, this feedback includes feeling the movements of your lips, tongue and jaw, and hearing the sounds of your own voice. In non-stuttered speech the cerebellum is active but not greatly so. stutterer non-stutterer

Movement coordination (stutterer) Activation in this movement coordination center (the cerebellum) is much greater during stuttered speech than during non-stuttered speech. This suggests that the brain's timing and coordination of motor programs are very impaired in stuttering, while the movement programming and movement execution functions are intact. speech preparation stutterer non-stutterer movement preparation movement release mouth movement movement coordination hearing (yourself speak)

Hearing (non-stutterer) Sounds, including the sound of one’s voice, are interpreted (“decoded”) in the superior temporal area. In non-stutterers, this area is very active, indicating that self-listening is an important part of normal speech. Notice that this activity is mostly on the left side, as is the case with almost all brain areas used for speech and language. stutterer non-stutterer

Hearing (stutterer) Activation in this hearing center (the superior temporal area) is much weaker in stutterers than in non-stutterers. This indicates self-listening (of speech) is minimally used by stutterers, although it is an important part of speech in non-stutterers. Whether this is a cause or a compensation is not yet known. speech preparation stutterer non-stutterer movement preparation movement release mouth movement movement coordination hearing (yourself speak)