Example of two <i>NTS</i> Inspiratory neurons during breathing and swallow.

<p>Unsorted and sorted spike trains, and instantaneous firing frequency (FF) (Hz) are displayed; demonstrating an increase in FF during swallow. The swallow is outlined in the gray box. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199903#pone.0199903.t002" target="_blank">Table 2</a> for anatomical location and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199903#pone.0199903.t001" target="_blank">Table 1</a> for neuron discharge pattern definitions. Recordings of EMG moving averages from the mylohyoid, thyrohyoid, parasternal, diaphragm and esophageal pressure are also shown.</p

Neurons recorded from the dorsomedial medulla described by neuron discharge identity; depth; coordinates for medial-lateral (ML); rostral-caudal (RC); the maximum peak-to-peak firing frequency (FF; in Hz) during breathing and swallow; and direction of change.

<p>Neurons are arranged by discharge identity (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199903#pone.0199903.t001" target="_blank">Table 1</a> for descriptions) and the NTS/dorsal respiratory group neurons (< 2500 μm depth) are <i>italicized</i>. Neurons displayed in Figs are noted under the identity column.</p

Suppression of Abdominal Motor Activity during Swallowing in Cats and Humans - Table 1

<p><b>A</b>. Changes to inspiratory and expiratory EMG amplitude and duration comparing cycles with expiratory loading and expiratory loading with swallow. <b>B</b>. Changes to laryngeal, pharyngeal, and schluckatmung EMG amplitude during control swallows (rest breathing) and swallows during expiratory threshold loading.</p><p>Suppression of Abdominal Motor Activity during Swallowing in Cats and Humans - Table 1 </p

Terms used, acronyms, and definitions for neuron discharge patterns.

<p>Terms used, acronyms, and definitions for neuron discharge patterns.</p

Neurons in the dorsomedial medulla contribute to swallow pattern generation: Evidence of inspiratory activity during swallow

<div><p>Active contraction of the diaphragm and other inspiratory pump muscles during swallow create a negative thoracic pressure to improve the movement of the bolus (food/liquid) into the esophagus. We tested the hypothesis that dorsomedial medullary inspiratory neurons, including the nucleus tractus solitarius (NTS, pre-motor to the phrenic) would be active during swallow induced by oral water infusion. We recorded neurons in the NTS and medial reticular formation in anesthetized spontaneously breathing cats, and induced swallow by injection of water into the oropharynx. Our results indicate that: <i>1)</i> a majority of inspiratory cells in the dorsomedial medulla are active during swallow, 2) expiratory neurons are present in the medial reticular formation (deeper to the NTS) in unparalyzed cats and a majority of these cells decreased firing frequency during swallow. Our findings suggest that the dorsomedial medulla is a source of inspiratory motor drive during swallow and that a novel population of breathing-modulated neurons that also are modulated during swallowing exist in the medial reticular formation in unparalyzed animals.</p></div

Example of 6 <i>MRF</i> neurons (3-I and 3-E) during breathing and swallow.

<p>Unsorted and sorted spike trains, and instantaneous firing frequency (FF) (Hz) are displayed; demonstrating an increase in FF during swallow for the two I neurons. <b>A</b> also demonstrates more complicated swallow-related changes in the Late-E neurons firing frequency, with the second example having a longer suppression duration. <b>B</b> demonstrates a representative example of suppression of an E neuron during swallow. They often fire across the entire E duration, except during the execution of swallow. The swallows are outlined in a gray box. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199903#pone.0199903.t002" target="_blank">Table 2</a> for anatomical location and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199903#pone.0199903.t001" target="_blank">Table 1</a> for neuron discharge pattern definitions. Recordings of EMG moving averages from the mylohyoid, parasternal, diaphragm (B only) are also shown.</p

An example of swallowing in a young healthy male, and the abdominal suppression across the entire expiratory period.

<p>Note the small burst of abdominal activity at the beginning and the larger burst of abdominal activity at the end of the expiratory period was the consistent pattern.</p

Suppression of Abdominal Motor Activity during Swallowing in Cats and Humans - Fig 1

<p>A. Example of abdominal motor unit suppression with swallow. Note the positive wave on the esophageal pressure channel. This is indicative of the peristaltic wave during the esophageal phase of swallow. Swallow is denoted by the arrow, the first 2 cycles occurred on the inspiratory-expiratory phase transition, the third is during the inspiratory phase of breathing. B. Line graph depicting average change in abdominal EMG amplitude for each of the five animals. N denotes the expiratory cycle that contained the swallow, n-1 to n-3 are the three preceding expiratory cycles, and n+1 to n+4 are the four following expiratory cycles. Four of the five animals had evidence of a multi-cycle suppression. For this analysis only single swallows which had 3 respiratory cycles preceding and following the swallow were included in this analysis.</p

Summary of neuron discharge patterns and changes in peak firing frequency (FF) during swallow for all recorded neurons.

<p>See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199903#pone.0199903.t001" target="_blank">Table 1</a> for neuron discharge pattern definitions.</p

Display of recording location and depth at ~0.8mm rostral to obex.

<p>Light gray represents the NTS and dark gray the medial reticular formation (MRF). Acronyms: S (solitary track; DMV (dorsal motor nucleus of the vagus); 12 (hypoglossal nucleus); AMB (nucleus ambiguus); and 12N (hypoglossal nerve). Fig was modified from Berman [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199903#pone.0199903.ref029" target="_blank">29</a>].</p