Fig. 6.

Effects of a threshold dose of fentanyl on spike train properties of the AugI laryngeal motoneuron depicted in Fig. 5. A: fentanyl lengthens the inspiratory phase laryngeal neuron discharge and slows action potential frequency. Dashed lines emphasize the more negative discharge threshold after giving fentanyl. Thresholds of all action potentials were measured to derive the mean frequencies and standard deviations of control and fentanyl-affected discharges. B: autocorrelograms that illustrate pronounced increases in oscillation and burst patterns after fentanyl administration. C: power spectral density plots. Under control conditions, power peaks are evident at 2–4 Hz, whereas after giving fentanyl, a single, more prominent peak is evident at 2 Hz.