Sucking versus swallowing coordination, integration, and performance in preterm and term infants.

Mammalian infants must be able to integrate the acquisition, transport, and swallowing of food to effectively feed. Understanding how these processes are coordinated is critical, as they have differences in neural control and sensitivity to perturbation. Despite this, most studies of infant feeding focus on isolated processes, resulting in a limited understanding of the role of sensorimotor integration in the different processes involved in infant feeding. This is especially problematic in the context of preterm infants, as they are considered to have pathophysiological brain development and often experience feeding difficulties. Here, we use an animal model to study how the different properties of food acquisition, transport, and swallowing differ between term and preterm infants longitudinally through infancy to understand which processes are sensitive to variation in the bolus being swallowed. We found that term infants are better able to acquire milk than preterm infants, and that properties of acquisition are strongly correlated with the size of the bolus being swallowed. In contrast, behaviors occurring during the pharyngeal swallow, such as hyoid and soft palate movements, show little to no correlation with bolus size. These results highlight the pathophysiological nature of the preterm brain and also demonstrate that behaviors occurring during oral transport are much more likely to respond to sensory intervention than those occurring during the "pharyngeal phase."NEW & NOTEWORTHY Physiological maturation of infant feeding is clinically and developmentally significant, but seldom examined as an integrated function. Using longitudinal high-speed videofluoroscopic data, we found that properties of sucking, such as the length of the suck, are more sensitive to swallow physiology than those associated with the pharyngeal swallow itself, such as hyoid excursion. Prematurity impacted the function and maturation of the feeding system, resulting in a physiology that fundamentally differs from term infants by weaning.