Raw electromyographic traces of swallow stimulated by the three conditions.

<p>Note the increased burst amplitude of the mylohyoid and post-swallow cricopharyngeus with the addition of water, and increased duration of the parasternal muscle electromyogram during pharyngeal swabbing.</p

Effect of swallow stimuli on normalized electromyogram amplitude (% of maximum) and durations (ms) of selected swallow-related muscles, over the three stimulus conditions.

<p>*Significant effect (repeated measures ANOVA, P<0.05), significant difference (post-hoc test) from both other stimuli conditions (P<0.05).</p><p>Effect of swallow stimuli on normalized electromyogram amplitude (% of maximum) and durations (ms) of selected swallow-related muscles, over the three stimulus conditions.</p

Pearson product moment correlation scatter plot examples for the comparisons with the largest <i>r</i> values.

<p>Pearson product moment correlation scatter plot examples for the comparisons with the largest <i>r</i> values.</p

Pearson Correlations comparing electromyogram amplitude and duration during swallowing.

<p>All data was pooled over the three conditions: water only, water plus punctate mechanical stimulation and pharyngeal swabbing.</p><p>Pearson Correlations comparing electromyogram amplitude and duration during swallowing.</p

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

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

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

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