A. Respiration (top) and LFP (bottom two) traces during normal breathing. The respiration signal was recorded with a thermistor and its unit is arbitrary. LFP recording sites were 610 um apart. Solid curves are the signals after band-pass filtering in 0.5-10 Hz. Raw LFP signals are plotted with shaded colors. B. Same as A, but during accelerated breathing after hypoxia. C. Auto-correlation of the respiration and the LFP signals (left) and cross-correlation between the respiration signal and each of the LFP signals (right) during normal breathing. D. Same as C, but during accelerated breathing. E. Summary of phase-amplitude coupling analysis on the LFP data. The strength of the coupling between the phase of the respiratory frequency and the amplitude of a range of frequencies between 1 and 256 Hz was assessed in terms of the mean vector length. Analysis was performed on 52 and 14 LFP segments (duration: 50 sec) from normal and bulbectomized mice, respectively. The fraction of significant samples is plotted as a function of amplitude frequency.