Abstract
ObjectiveThe pharyngeal phase of swallow has been thought to be a stereotypical motor behavior.Study DesignThis is a prospective, preclinical, hypothesis driven, one group by three-task design.MethodsWe sought to compare the effects of pharyngeal swabbing, water only, and water plus punctate mechanical stimulation on the spatiotemporal features of the pharyngeal phase of swallow in the cat. Swallow was elicited under these three conditions in six anaesthetized cats. Electromyographic activity was recorded from seven muscles used to evaluate swallow: mylohyoid, geniohyoid, thyrohyoid, thyroarytenoid, thyropharyngeus, cricopharyngeus, and parasternal.ResultsPharyngeal swabbing in comparison to the other stimulus conditions, results in decreases in post-swallow cricopharyngeus activity (upper esophageal sphincter); a significant increase in parasternal (schluckatmung; swallow breath) activity; and increases in thyrohyoid (laryngeal elevator), thyroarytenoid (laryngeal adductor) and parasternal muscles burst duration. Pearson correlations were found of moderate strength between 19% of burst duration comparisons and weak to moderate relationships between 29% of burst amplitude comparisons. However, there were no positive significant relationships between phase durations and electromyogram amplitudes between any of the muscles studied during swallow.ConclusionsThe results support the concept that a stereotypical behavior, such as pharyngeal swallowing in animal models, can be modified by sensory feedback from pharyngeal mucosal mechanoreceptors. Furthermore, differences in swallow phase durations and amplitudes provide evidence that separate regulatory mechanisms exist which regulate spatial and temporal aspects of the behavior.
Highlights
Swallowing consists of three phases: oral, pharyngeal, and esophageal, each of which participates in a bolus transport from the oral cavity to the stomach [1,2,3,4,5,6,7]
The protocol was approved by the University of Florida Intuitional Animal Care and Use Committee (IACUC)
Laryngeal elevators, adductors, and pharyngeal constrictors all were activated in a ballistic-like manner (Figure 1) during each stimulus condition
Summary
Swallowing consists of three phases: oral, pharyngeal, and esophageal, each of which participates in a bolus transport from the oral cavity to the stomach [1,2,3,4,5,6,7]. As noted by Thexton et al [15,16], Doty and Bosma [2] observed considerable variation in electromyogram patterns of some upper airway muscles during swallowing. These investigators observed non-swallow behaviors in their recordings, in particular, the aspiration reflex. This knowledge, along with a study by Patterson [17], motivated Thexton et al [15] to re-address some issues that Doty and Bosma [2] had studied. Multiple sensory modalities can influence swallow including: perceptual factors of food appearance, taste, and mechanosensory feedback from oral mucosa/tongue regarding bolus consistency potentially accounting for the aforementioned observations
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