Functional imaging during speech production.

Physiological studies of speech production have demonstrated that even simple articulation involves a range of specialized motor and cognitive processes and the neural mechanisms responsible for speech reflect this complexity. Recently, a number of functional imaging techniques have contributed to our knowledge of the neuroanatomical and neurophysiological correlates of speech production. These new imaging approaches have the advantage of permitting study of large numbers of normal and disordered subjects but they bring with them a host of new methodological concerns. One of the challenges for understanding language production is the recording of articulation itself. The problems associated with measuring the vocal tract and measuring the neural activity during overt speech are reviewed. It is argued that advances in understanding fundamental questions such as what are the planning units of speech, what is the role of feedback during speech and what is the influence of learning, await the development of better methods for assessing task performance.