Figure 2. Cartoon depicting the location of the rhythmic brainstem slice, the output targets of the hypoglossal nerves, and typical spontaneous hypoglossal nerve bursts.

Panel A, schematic of the medulla and rostral spinal cord showing the approximate region from which the 700μm thick rhythmic slice is taken (represented by dashed box). The XII nerve rootlets are shown in gray, with the arrow illustrating output to the tongue muscles (cartoon showing the human tongue and upper airway reproduced with permission from Ivanhoe (1999)). Panel B, Nissl stained transverse section through the medulla with the regions of interest highlighted with black arrows on the left half of the image. Right half shows general schematic of neuronal connections of interest within the slice (more detailed wiring diagram provided in Fig. 1). Orange symbols and line represent a preBötC neuron, teal represents an interneuron, and maroon represents a hypoglossal motoneuron that exits the slice in a XII nerve rootlet. Panel C, example of the spontaneous rhythmic bursting activity obtained from a suction electrode recording, as shown in Panel B; ENG, electroneurogram. Panel D is an expanded example of one of the respiratory bursts shown in Panel C, showing both the unprocessed ENG and the rectified and integrated ENG (∫ENG), as well some of the burst parameters that were measured.