What dysarthrias can tell us about the neural control of speech

Dysarthrias, part of the class of neurogenic speech disorders, provide several sources of evidence concerning the neural control of speech. Although the dysarthrias have been studied primarily from a clinical perspective directed to issues of assessment and management, they have much to tell us about how the brain regulates the act of speaking. This paper considers five major areas in which disordered and normal speech can be integrated into an improved understanding of speech motor control: sensory function in the regulation of speech; rhythm as a temporal substrate for the organization of speech movements; kinematics of individual movements and motor systems; neural bases of multi-articulator coordination; and strategies for compensation, adaptation, and re-organization. A theme that runs through these five areas is consideration of the overarching hypothesis that speech motor regulation is based on a modular organization that can be defined partly by consideration of results from neurogenic speech disorders.