Modeling Motor Planning in Speech Production Using the Neural Engineering Framework

Background: Currently, there exists no comprehensive and biologically inspired model of speech production that utilizes spiking neuron. Goal: We introduce a speech production model based on a spiking neuron approach called the Neural Engineering Framework (NEF). Using the NEF to model temporal behavior at the neural level in a biologically plausible way, we present a model of the temporal coordination of vocal tract actions in speech production (i.e. motor planning) with neural oscillators. Method: Neural oscillators are postulated in our model at the syllable and vocal tract action level. They define relative or intrinsic time scales for each vocal tract action as well as for each syllable and thus allow intrinsic timing or phasing of speech actions. Results: The model is capable of producing a sequence of syllable-sized motor plans that generate muscle group activation patterns for controlling model articulators. Simulations of syllable sequences indicate that this model is capable of modeling a wide range of speaking rates by altering individual syllable oscillator frequencies. Conclusions: This approach can be used as a starting point for developing biologically realistic neural models of speech processing.