DAF in Stuttering: A Potential Anatomical Link

At this juncture neuroscientists believe that developmental stuttering is a complex motor speech disorder with a strong genetic link. Based on converging evidence from cognitive-behavioral, genetic, neurophysiological and neuroanatomical studies, we have learned that it is likely that stuttering does not result from one causative factor. Furthermore, there is increasing evidence that biological subtypes may be demonstrable with the potential that different therapies may benefit different biologically specific types of stuttering. In a series of recent studies our research group has focused on the anatomy and functional representation of the auditory system in individuals with developmental stuttering.

Research on Incidence and Prevalance

In a recent conference on stuttering sponsored by the National Institute on Deafness and Other Communication Disorders (NIDCD), I discussed several factors related to predisposition to stuttering. These include (a) occurrence, (b) age, (c) gender, (d) genetics, (e) stressors, (f) concomitant disorders, (g) persistency-recovery, and (h) subtypes.

New Research on the Roots of Stuttering: Language Processing and Speech Motor Control: Complex Interactions in Stuttering

In the last decade, accumulating evidence from laboratories in the U.S. and Europe, as well as our own, led to the development of a multi-factorial model of stuttering. This model of stuttering hypothesizes that stuttering emerges from complex interactions among factors including genetics, language processing, emotional/social aspects, and speech motor control. Ultimately, stuttering occurs when the neural signals that produce the coordinated movements in the respiratory, vocal, and articulation systems become disrupted. The underlying notion is that the functions of the brain areas for speech motor control are affected by complex interactions with other neural systems. One important underlying assumption of this model is that these factors may not play the same role in different individuals who stutter and very likely vary in significance over different stages of development.

Neural Bases of Stuttering and its Treatment

Researchers and clinicians working in the area of stuttering recognize that the cause of stuttering is complex. Over the years, many different explanatory models of stuttering causation have been proposed. One of the most persistent themes in several of these models has been that stuttering may be related to abnormal brain processes involved in speaking. As early as 1928, Samuel Orton and Lee Travis offered a neurophysiological model of stuttering. They speculated that stuttering resulted from incomplete development of hemispheric dominance. Although the early model proposed by Orton and Travis was ultimately not supported experimentally, the idea that atypical brain processing for speech somehow plays a role in stuttering has received ongoing attention over the years.

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