Fig. 2.

Central drive to the diaphragm muscle (DIAm), as measured by RMS DIAm EMG at the initial 75 ms (RMS₇₅), and peak RMS EMG normalized to the maximal RMS EMG value observed during sneezing. A: representative RMS EMG traces averaged within an animal across motor behaviors. Dashed line at 75 ms indicates the point at which RMS₇₅ was calculated (see methods for details). B: normalized RMS₇₅ (open bars) and peak RMS EMG (black bars) across DIAm motor behaviors (expressed as % of maximum RMS EMG displayed during sneezing). RMS₇₅ was comparable during eupnea and hypoxia-hypercapnia. Deep breaths presented higher RMS₇₅ value compared with eupnea (P < 0.05). RMS₇₅ was substantially higher during airway occlusion (P < 0.001). Peak RMS EMG progressively increased from eupnea to hypoxia-hypercapnia (P < 0.01) and to deep breath (P < 0.001). During airway occlusion, peak RMS EMG was comparable to deep breaths (P > 0.05) but greater than eupnea (P < 0.001) and hypoxia-hypercapnia (P < 0.001). *P < 0.05 vs. eupnea; #P < 0.05 vs. hypoxia-hypercapnia; &P < 0.05 vs. deep breaths; §P < 0.05 vs. RMS₇₅ for same behavior.