Neural bases of speech production: contribution of common action control mechanisms

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The act of speaking is an extremely complex behaviour. It begins with an intention to communicate, continues to the translation of the message into words, which in turn need to be organised in a meaningful sequence (i.e. sequenced) and converted into series of fast and precise muscle contractions. Even though the production of speech occurs remarkably rapidly and seemingly effortlessly, the underlying neural mechanisms for speaking remain far from understood. One aspect of the neural organization of speech that is particularly unclear is the degree to which the speech system is integrated into a common action control system, an idea that is at odd with the dominant idea that the neural machinery for speech production is dedicated to the specific task of producing language. The central goal of my research program is to understand the manner and extent to which the neural speech system in integrated into a common action control system. To achieve this global objective, I study the neural bases of processes that are involved in speaking and in producing other complex behaviours (e.g. typing on a keyboard), such as responses selection and sequencing. My previous work has identified a common network of brain areas involved response selection for speech and other complex behaviours. The specific objectives of my research program are (1) to isolate the neural system underlying response sequencing across motor domains (speech, finger and hand movements), and (2) to identify the commonalities and differences in the network supporting response selection and sequencing mechanisms across motor domains. To achieve these objectives, an innovative 5-year research program is proposed that involves functional brain imaging and brain stimulation in healthy adults. The knowledge that will be generated through this research program has tremendous importance for the development of more comprehensive neurobiological models of speech and language, which typically do not integrate common action control mechanisms, focusing instead on language-specific mechanisms. A better understanding of the role of general action control mechanisms in speech production may lead to the development of new speech rehabilitation strategies.