In a large number of infants, both with and without underlying diseases or disorders, feeding poses significant challenges because they lack the ability to coordinate movements of tongue, jaw, and pharynx. Failure to coordinate these movements can lead to dysphagia which has significant short- and long-term impacts on health. With weaning, the tongue must produce more complex movements and deformations in coordination with jaw movements to manage a solid, multi-textured diet during bolus transport and processing prior to the pharyngeal swallow. Failure to do so can quickly result in airway blockage, choking and even death. Modifying foods by thickening liquids or pureeing solids can assist with feeding and provide adequate nutrition when necessary. However, if an infant is maintained on foods lacking a heterogeneous texture, the less they are challenged with oral processing tasks during critical periods of oral development, leading to further setbacks in chewing and swallowing. Studies of infant dysphagia in humans and animal models reveal much about the movements and motor control of the tongue, but this work is based primarily on suckling. In contrast, our understanding of the development and maturation of feeding in newly weaned infants comes primarily from studies of jaw movement and motor control during chewing, with little information on associated tongue movements. Furthermore, we also do not know how long-term use of texture modified foods during critical periods of oral maturation alters the functional and biomechanical development of the tongue and its coordination with the jaw. The proposed work will investigate maturation of tongue function, biomechanics and anatomy, and their effect on oral performance in an animal model for oral physiology and biomechanics. We will compare animals reared on a varied diet requiring processing (control) to those reared on a single texture soft diet (treatment). Novel methods for characterizing 3D tongue and jaw movements from biplanar fluoroscopy will allow characterization of kinematic measurements not feasible in humans. This study will determine how a widely used texture modification strategy for dysphagia affects the normal sensorimotor and anatomical development necessary for feeding on solids by completing 3 specific aims for the control and treatment animals: 1) Characterize the ontogeny and maturation of tongue kinematics and jaw-tongue coordination during feeding; 2) Describe the longitudinal maturation of the anatomy of tongue musculature. 3) Evaluate oromotor performance in pigs raised on a varied versus soft diet. This research will provide critical data on the postweaning feeding mechanism necessary for identifying the physiological, biomechanical and anatomical basis of pediatric dysphagia. This is essential for optimizing specific treatment and rehabilitation strategies for normal infants with dysphagia and those with underlying conditions that require long-term texture-modification of foods. Through completion of the aims, this project will also provide state-of-the art and clinically-relevant research opportunities for undergraduate, graduate and medical students.
The inability to coordinate tongue and jaw movements during feeding leads to poor growth and development in a significant number of normal and medically fragile infants and children. This project will determine how a widely-used intervention to safely maintain nutrition but provides limited oral sensory stimulation impacts the development of feeding movements in an animal model. Understanding the functional impact of this intervention for compromised feeding ability will inform decisions about patient care and management, thereby supporting NIH's mission to enhance health and reduce illness and disability.
