Fig. 9.

Effect of sciatic nerve stimulation on RTN neuron firing rate at low and high CO₂. A: traces from top to bottom and abbreviations as in Fig. 8. Sciatic nerve stimulation (0.5 Hz) was delivered during a period of low (4%) and high (6.4%) eeCO₂. At 4% eeCO₂, the neuron was silent in the absence of stimulation. B: from top to bottom: higher-resolution excerpt of the unit's response to contralateral sciatic nerve stimulation (stimuli at arrowheads; stimulus artifacts eliminated), poststimulus time histogram (stimuli delivered at time 0) of the neuronal activity showing bimodal activation, and poststimulus time histogram of the onset of the PND evoked by nerve stimulation. C: response of the same unit to sciatic nerve stimulation during period of elevated eeCO₂ (presentation as in B). D: average response (mean ± SE) evoked in 7 RTN neurons by sciatic nerve stimulation during inspiration (top) or during expiration (bottom). Stimulus delivered at arrowhead; stimulation artifacts eliminated.