Meeting Abstract
Mammalian swallowing is complex at anatomical, functional, and neurological levels. The complexity of swallowing physiology means that multiple points may lead to similar failure in performance, specifically failure to protect the airway. The superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN) are branches of the Vagus that innervate different structures involved in swallowing. Although they have distinct sensory and motor fields, lesion of either nerve leads to a decrease in airway protection. We tested the hypothesis that despite similar outcomes in terms of airway protection, SLN and RLN lesion would impact oropharyngeal kinematics differently. To test the effect of lesion of either nerve on kinematics, we recorded 11 infant pigs swallowing milk using high speed videofluoroscopy before and after either unilateral SLN or RLN lesion. Because of the repeated measures design each animal acted as its own control. We measured oropharyngeal kinematics from the videofluoroscopic recordings. Posterior tongue kinematics during swallowing respond differently to RLN lesion and SLN lesion (p=0.007). Furthermore the relationship between tongue kinematics and airway protection outcome differs in SLN and RLN lesion (p=0.045). Thus, although SLN and RLN lesion lead to the same performance failure, the effect on tongue kinematics and their relationship to airway protection failure are different. The complex connections that exist in mammalian feeding systems result in a many-to-one relationship between function and performance, and has significant implications for understanding how complex systems are functionally integrated in ontogeny and evolution.
