FIGURE 1.

Patterns of motor activities and artificial ventilation during breathing and swallowing in the various conditions. (A–D) Subject-triggered (ST) ventilation. (E–H) Mandatory ventilation (MV). Distinct bursts on the integrated hypoglossal (XII) and vagal (X) raw nerve activities, as shown in (A,B), were used to identify single swallows elicited by electrical stimulation of the superior laryngeal nerve (SLN) (A,C,E,G) or pharyngeal water injection (B,D,F,H). Swallows were classified as post-inspiratory (Post-I) or expiratory (Exp) according to the timing of XII burst initiation (red arrow) with respect to peak phrenic activity. Post-I swallows (A,B,E,F) occurred after the peak of a preceding phrenic (Phr) activity and before the end of its decrementing post-inspiratory activity, whether or not the ongoing inspiratory phase was interrupted. Exp swallows (C,D,G,H) occurred after full completion of the Phr burst including its decrementing post-inspiratory activity. Swallows were associated with a small non-respiratory Phr burst, also known as Schluckatmung (S), which occasionally triggered the mechanical ventilator in ST mode (C). When an Exp swallow occurred (C,D,G,H), the S was visible and separate from inspiratory-related Phr activity (indicated by black dashed line). By contrast, when a Post-I swallow occurred, S often merged with the preceding inspiratory-related Phr activity, resulting in a small indentation on the Phr envelope (A,B,E,F). Note the shorter or longer duration of the cycles which contain a Post-I or a Exp swallow (N), respectively, compared to previous control respiratory cycles (N-1).