Research
We study the dynamics of feeding and drinking in mammals. We are specifically interested in 1) how the jaw, tongue, hyolaryngeal, and pharyngeal muscles make this complex behavior happen from a motor control perspective, 2) the structure-function relationships that contribute to differences in movements and coordination, and 3) how sensory systems assist with dynamic modulation of the underlying muscle activity and kinematics. Our work takes both an evolutionary and clinical approach. Comparisons between species are useful for shedding light on how evolutionary shifts in diet and morphology contribute to differences in movements. Because mammals are notable in having radically different infant and adult feeding behaviors (suckling and a liquid diet versus chewing and a solid diet) and oftentimes protracted weaning periods, comparisons within species throughout early ontogeny are useful for understanding fundamental aspects of motor control development, especially in the context of changing anatomy (e.g., tooth eruption). Other studies compare among different treatments to allow for a more mechanistic understanding of very complex behaviors.
Texture modification as dietary strategy for infants and children with oropharyngeal dysphagia
In infants, the successful transition to solid foods typically occurs during a critical window of oral development. Otherwise healthy children who fail to wean during this window or those with musculoskeletal or neurological disorders are often sustained on a texture modified (liquid or soft) diet to treat dysphagia, difficulty eating and swallowing. Long-term early use of this diet can cause structural abnormalities of the orofacial region and aberrant chewing patterns. Currently, we do not know how to remediate and safely facilitate maturation of chewing function when this occurs. In collaboration with Dr. Donna Scarborough, CCC/SLP at Miami University, we are testing two treatment strategies to recover oral function using an animal model. This work will guide clinical decisions for feeding rehabilitation in children and lay the groundwork for helping children with underlying physical and/or neurological disabilities that delay the acquisition of oral skills. Funded by the NIH Eunice Kennedy Shriver National Institute of Child and Human Development.
Anatomy, evolution, and biomechanics of swallowing in mammals
The hyoid bone of mammals lies at the base of the tongue and is connected to the skull by a chain of ligaments, muscles, and bones. Hyoid movement is thought to be important for swallowing, but it is not known whether variation in hyoid anatomy across mammals is associated with different swallowing mechanisms. In collaboration with Dr. Callum Ross, Dr. Zhe-Xi Luo, and Dr. Peishu Li, this project will document hyoid chain variation in two clades of mammals, Euarchontoglires and Laurasiatheria, by quantifying the relationships between hyoid, pharyngeal, and lingual anatomy, and determine whether interspecific variation in hyolingual and pharyngeal anatomy is associated with differences in swallowing biomechanics. Funded by the National Science Foundation.
The development of mastication and tongue biomechanics
Mastication, or chewing, is a slowly developing behavior that culminates in complex tongue and jaw coordination. This coordination is essential for allowing us to consume texturally and physically complex foods. In children where tongue and jaw coordination is not achieved during these critical periods, outcomes include poor growth and a long-term reliance on interventions, such as dietary texture modification, or liquidized diets, which provide limited sensory stimulation. This project will determine how this widely-used intervention to safely maintain nutrition 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 in infants and children. Funded by the NIH Eunice Kennedy Shriver National Institute of Child and Human Development.
Evolutionary and neurosensory influences on mammalian chewing kinematics
Mastication, or chewing, results in the fine breakdown of food. Neurophysiologically, it is a behavior that involves very complex integrated movements of the jaw, tongue and hyoid. Jaw movements precisely align the teeth to break down the food, and the tongue, supported by the hyoid, maintains the food on the teeth and helps bolus formation. Morphological specializations for diet in the teeth, temporomandibular joint, and other structures influence these movements, as do the connections between oral sensory receptors and central and peripheral motor systems. The goal of this study is to determine how oral sensory information and morphology interact to influence chewing movements and their variation. Results will shed light on potential selective pressures influencing the evolution of sensory and motor systems involved in mastication. Funded by the National Science Foundation.
Effects of lingual nerve injuries on oromotor function
Lingual nerve injury occurs during routine dental procedures, producing pain and numbness in the tongue and impacting the patient's ability to feed. This project uses an animal model (pig) to understand the physiological and functional consequences of lingual nerve injury on oromotor behavior and the neurophysiological control of tongue and jaw movements movements following these injuries. Our goal is to identify functional changes and compensatory mechanisms in the tongue and jaw following lingual sensory disturbances as a foundation for developing specific management and rehabilitation strategies for patients with lingual nerve injuries. Funded by the NIH National Institute of Dental and Craniofacial Research.