Comparison of model simulations with experimental data.

<p><b>A</b>. Breathing stimulation elicited in conscious adult rat in a flow-through, whole-body plethysmography chamber by photostimulation via channelrodopsin genetically engineered in RTN Phox2b-expressing glutamatergic neurons. The left diagrams were constructed for hyperoxic normocapnia (100% O₂), and the right diagrams for hypercapnia (8% CO₂, balance O₂). Continuous RTN stimulation (23 Hz, 3 ms pulses, 30 s total duration, blue bar at the top) raised tidal volume, V_T, and breathing frequency, fR. During hyperoxic hypercapnia (right), RTN photostimulation produced a small increase in V_T but no increase in fR. Adapted from Abbott et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109894#pone.0109894-Abbott1" target="_blank">[52]</a>, Fig. 1B, with permission. <b>B</b>. The results of our simulations. An additional 30s-duration increase in the blood CO₂ level (Δ<i>p_c</i> = 30 mmHg, blue bar at the top) was applied in the normocapnic case (left) and on the background of simulated hypercapnia (<i>f_cm</i> = 8%) (right).