Oromotor functional networks in the marmoset monkey

Primate communication relies on the precise coordination of the orofacial complex. While New World monkeys are growing models for vocal communication research, the neural basis underlying their oromotor control remains underexplored. Here, we used ultra-high-field fMRI in awake common marmosets (Callithrix jacchus) to map the whole-brain neural networks engaged during spontaneous visible oromotor functions-including jaw and lip movements, tongue protrusion, swallowing, and vocalization-distinct from those recruited during the auditory processing of conspecific calls. The resulting oromotor maps reveal a widespread control substrate extending beyond primary sensorimotor cortices, encompassing dorsal prefrontal (areas 8aD, 8b), mid-cingulate, posterior parietal areas (PF, PFG, and PE), and auditory regions. The parietal engagement points to a role for sensorimotor integration in marmoset oromotor control. Subcortically, this network engages the thalamus, basal ganglia, and cerebellum, with additional activation in the medullary reticular formation and periaqueductal gray, brainstem regions implicated in rhythmic oromotor control. A predominantly dorsal pattern of activation, with limited ventral premotor engagement, defines this network and provides a foundational framework for future studies of vocal-motor control in this species and a comparative reference for the rhythmic oromotor substrates from which speech is hypothesized to have evolved.