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Neural dynamics of speech content and production
Poster Session F, Friday, October 2, 2:45 - 4:45 pm, Wangari Maathai
Vera A. Voigtlaender1,2,3,4, Florian Sandhaeger1,2,3, Markus Siegel1,2,3; 1Hertie Institute for Clinical Brain Research, University of Tübingen, Germany, 2Centre for Integrative Neuroscience, University of Tübingen, Germany, 3MEG Center, University of Tübingen, Germany, 4Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tübingen, Germany
Despite its importance for human communication, the neural mechanisms underlying speech production remain poorly understood. It can occur overtly or covertly, providing a way to investigate how speech content relates to motor execution. Furthermore, we can distinguish the lexical and sub-lexical levels of speech. Here, we focus on the sub-lexical level to investigate how speech unfolds from content toward implementation. We recorded Magnetoencephalography (MEG) in human subjects performing a rule-based vocalization task. Content (one of three vowels) and production (overt or covert) were instructed sequentially in this order, allowing us to trace how vocalization unfolds from purely content-related to production-dependent representations. With multivariate pattern analysis (MVPA), source reconstruction and distance-based embedding methods, we reconstructed the geometry of content representations in relation to temporal and production representations. We found that sub-lexical vocalization unfolds in a structured neural state space: content representations were at least two-dimensional and generalized across production types, while temporal progression and production planning introduced additional changes that were organized largely orthogonal to content. Our results provide essential insights into the neural dynamics underlying sub-lexical speech production, and may help reveal fundamental principles that also inform more complex forms of speech.
Topic Areas: Speech Motor Control,