To what extent does tagged-MRI technique allow to infer tongue muscles' activation pattern? a modelling study

‘Tagged MRI’ techniques have been used during the past years to predict which tongue muscles are activated during the production of vowels and for non-speech gestures. Using this technique, tongue muscle activation inferences are based on the hypothesis that a significant distortion of the anatomical region of a tongue muscle is evidence of voluntary muscle activation. In this paper, we propose to use a 3D finite-element model of the oral cavity to study the relation between the strain levels observed in the tongue body in relation to the tongue muscles activated by the central nervous system or through reflex loops. Results showed in most cases a good correlation between the area of the tongue that underwent high strains and the location of the muscle activated when studying single muscle activation, but a limited and even no correlation for movements involving combined muscle activation. A direct reading of Tagged MRI images would not allow inferring major tongue muscles activated in theses cases. Index Terms: Tagged MRI, speech production, biomechanical modelling