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. Author manuscript; available in PMC: 2014 Nov 1.
Published in final edited form as: Respir Physiol Neurobiol. 2013 Jun 7;189(2):10.1016/j.resp.2013.06.001. doi: 10.1016/j.resp.2013.06.001

Figure 4.

Figure 4

SMU activity recorded from the parasternal intercostal muscle, external intercostal muscle and diaphragm during spontaneous breathing (left panel) and during HF-SCS (right panel) in one animal. EMG, instantaneous motor unit discharge frequency and the corresponding volume are plotted in each panel. All the action potentials from each SMU are superimposed on the right. Note that during both spontaneous breathing and HF-SCS, discharge frequencies of single motor units gradually increase during the first part of inspiration until a plateau is reached and then gradually decline. Note also that there were no significant differences in SMU firing frequencies between spontaneous breathing and HF-SCS.