CAREER: Uncovering the neural dynamics of speech monitoring processes during language production

San Diego State University Foundation, San Diego CA

Investigators

Abstract

Language is one of the distinctive cognitive faculties that is unique to humans. We often take our fluency in speech production for granted. Remarkably, although adult, native-language speakers can produce 2 to 3 words per second as they speak, they only make speech errors about once every thousand words! Speech monitoring is the mechanism by which we control our speech production so efficiently to avoid or correct errors as we are speaking. Importantly, we are able to monitor our speech both before and after we have heard ourselves speak, but how our brain supports speech monitoring is still unclear and is the focus of this study. The researchers will challenge speakers with tongue-twisters and other speech tasks and use a powerful technique to study brain activity during task performance. They will investigate which parts of our brain allow us to monitor our speech production before versus after we hear ourselves speak. They will also examine how these brain regions interact with one another. The results of this research will help us understand how humans monitor their speech production in real time and will be relevant to understanding how and why speech monitoring function can become impaired in speech disorders such as aphasia. These studies may also lead to insights as to how speech impairment can be corrected. Researchers will develop an outreach program centered around lectures on language and the brain to bring these insights to a broad, general audience, and to provide educational opportunities from elementary school to graduate school. In this project, the combined excellent spatial and temporal resolution of intracranial electroencephalography (iEEG), a brain imaging technique, will be used to precisely identify which brain regions are involved at which stage of speech monitoring while we produce language. Specifically, researchers will use the high resolution of iEEG to investigate whether speech perception is independently engaged in monitoring our speech before we actually produce it, or whether instead, inner speech monitoring relies more on our speech production system in tandem with domain-general action monitoring. The results of this research will help resolve competing cognitive models of how we monitor speech production, and also will illuminate how the different brain regions involved in speech monitoring functionally interact in real time before versus after speech output. Because iEEG is an invasive brain imaging technique that is used for clinical monitoring purposes in patients with epilepsy (to localize epileptic foci for surgical removal), it is also necessary to establish whether the behavioral results found in the patients who have volunteered for this study, fall within the normal range. Therefore, researchers will in parallel collect behavioral data online in control participants in order to compare the performance of patients with epilepsy to that of normal, matched controls. Overall, this research will be transformative and will have tremendous impact in neuroscience, cognitive psychology and psycholinguistics and provide deeper understanding of the impressive monitoring and error-correcting mechanisms in our brains that enable us to speak clearly. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.