Brain activations in speech recovery process after intra-oral surgery: an fMRI study

This study aims at describing cortical and subcortical activation patterns associated with functional recovery of speech production after reconstructive mouth surgery. Our ultimate goal is the understanding of how the brain deals with altered relationships between motor commands and auditory/orosensory feedback, and establishes new interarticulatory coordination to preserve speech communication abilities. A longitudinal sparse-sampling fMRI study involving orofacial, vowel and syllable production tasks on 9 patients and in three different sessions (one week before, one month and three months after surgery) was conducted. Healthy subjects were recorded in parallel. Results show that for patients in the pre-surgery session, activation patterns are in good agreement with the classical speech production network. Crucially, lower activity in sensorimotor control brain areas during orofacial and speech production movements is observed for patients in all sessions. One month after surgery, the superior parietal lobule is more activated for simple vowel production suggesting a strong involvement of a multimodal integration process to compensate for loss of tongue motor control. Altogether, these results indicate both altered and adaptive sensorimotor control mechanisms in these patients.