Fig. 3.

An example of extracellular recording of a single neuron within the vl part of RTN/pFRG during hypercapnia (7% CO₂), the activity of which correlated with the abdominal late-E bursts. A: the 2 bottom traces show integrated activities of PN (red) and AbN (black) nerves; the 2nd trace shows raw activity of the RTN/pFRG neuron, and the top trace shows the corresponding spike-frequency histogram of this neuron activity (bin = 0.1 s). Note that the neuronal bursts were skipped whenever AbN bursts were skipped, reflecting their synchrony. B: interdependence between the RTN/pFRG neuron discharges (shown in A) and AbN late-E bursts. Integrated activities of AbN and RTN/pFRG neuron are shown in arbitrary units (a. u.) during a 300 s epoch with sampling frequency of 100 Hz (30,000 points in total) and plotted against each other (red crosses). Dashed lines representing thresholds split the space into 4 quadrants. The top right quadrant represents cases where both cell activity and AbN late-E bursts were present (indicated by blue dashed ellipse); the bottom left quadrant represents cases where both cell and AbN late-E discharges were missing (indicated by another blue dashed ellipse) and only background activity is represented.