Variability of the Pharyngeal Phase of Swallow in the Cat

PLOS ONE, Dec 2019

Objective The pharyngeal phase of swallow has been thought to be a stereotypical motor behavior. Study Design This is a prospective, preclinical, hypothesis driven, one group by three-task design. Methods We 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. Results Pharyngeal 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. Conclusions The 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.

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Variability of the Pharyngeal Phase of Swallow in the Cat

Citation: Spearman DG, Poliacek I, Rose MJ, Bolser DC, Pitts T ( Variability of the Pharyngeal Phase of Swallow in the Cat Daniel G. Spearman 0 Ivan Poliacek 0 Melanie J. Rose 0 Donald C. Bolser 0 Teresa Pitts 0 Pavel Strnad, RWTH Aachen, Germany 0 1 Department of Physiological Sciences, University of Florida, Gainesville, Florida, United States of America, 2 Institute of Medical Biophysics, Jessenius Faculty of Medicine, Comenius University , Martin , Slovak Republic Objective: The pharyngeal phase of swallow has been thought to be a stereotypical motor behavior. Study Design: This is a prospective, preclinical, hypothesis driven, one group by three-task design. Methods: We 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. Results: Pharyngeal 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. Conclusions: The 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. - Funding: Funding provided by National Institutes of Health HL 89104, HL103415, HL109025, and HL107745. There are no other financial disclosures to report. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. Swallowing consists of three phases: oral, pharyngeal, and esophageal, each of which participates in a bolus transport from the oral cavity to the stomach [17]. The pharyngeal phase of swallowing is the movement of a bolus from the pharynx to the esophagus [3,810]. It can be initiated by touch, pressure, and/or similar action of a liquid on the tongue, faucial pillars, soft palate, uvula, epiglottis, pharyngeal wall, and/or junction of the pharynx/ esophagus [5,10,11]. The pharyngeal phase is a reflexive patterned behavior that has been hypothesized as stereotypic [1,2,1215]. Doty and Bosma [2] found no measurable difference in duration or amplitude of the measured muscles when swallow was elicited by superior laryngeal nerve stimulation, pharyngeal stimulation with a cotton swab, or rapidly injecting water into the pharynx. However, 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 also 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. Thexton and coworkers [15,16] and Sumi [18] confirmed pharyngeal muscle variation during swallowing in infant animals. These studies are consistent evidence in humans showing that the pharyngeal phase of swallow can be modified by bolus type, size, consistency, temperature, and taste i.e [9,11,1928]. Additionally, 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. Considering the motor pattern variance, in human or awakeanimal models, it is difficult to understand the role of feedback from oropharyngeal airway regions on the swallow motor pattern from previous work. In particular, separation of volitional factors as well as oral sensory feedback would reveal the influence of sensory feedback from sub-oral (pharyngeal) airway in modulation of the swallow motor pattern. For example, Patterson [17] in an anesthetized opossum model demonstrated significant differences in mylohyoid activation elicited by unilater (...truncated)


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Daniel G. Spearman, Ivan Poliacek, Melanie J. Rose, Donald C. Bolser, Teresa Pitts. Variability of the Pharyngeal Phase of Swallow in the Cat, PLOS ONE, 2014, 8, DOI: 10.1371/journal.pone.0106121