In a series of studies regarding CNS dysfunction in stuttering, we have examined linguistic and motoric performance in the context of measures of brain function. Previous studies of adults with developmental stuttering identified alterations in brain function (metabolic and electrophysiologic) in cortical regions implicated in models of speech motor control and language processing. We also identified a sub-group of these subjects who exhibited linguistic performance deficits related to speech performance deficits. The present study examined the hypothesis that adults who stutter and who show linguistic performance deficits will also show metabolic alterations in cortical regions classically related to language processing, whereas adults who stutter but who do not show linguistic performance deficits will not show these cortical metabolic alterations. Significant relative blood flow asymmetry (left < right) was observed in middle temporal and inferior frontal cortical regions only for adults who both stuttered and showed linguistic performance deficits. Results support models that explicitly recognize that efficient integration of linguistic, motoric, and cognitive processes is critical to the production of oral/verbal fluency and to understanding sources of fluency failure.
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