Figure 3: Olfactory bulb activity drives cortical oscillations.

Reduction of coherence between respiration and local field potential (LFP) signals in intact and olfactory bulbectomized mice recorded in awake, head-fixed conditions. (a) Respiration (black) measured as the temperature in front of the mouse’s nostrils and simultaneously recorded LFP signals (red and blue) in the barrel cortex of a bulbectomized mouse. The respiration signal was normalized by subtraction of the mean and division by the s.d. (b) Autocorrelations (left) of the LFP and respiratory signals shown in a and cross-correlations (right) between the respiratory signal and either of the LFP signals in a. Red and blue curves represent the cross-correlations obtained from the LFPs drawn by the corresponding colour in a. (c) Coherence between respiratory signals and LFP signals plotted against respiration frequency. Individual data points represent the coherence within a data segment of 50 s between respiration and the simultaneously recorded LFP signal. Different symbols represent different mice, and white and black symbols represent intact and bulbectomized mice, respectively. A total of 52 and 18 50-s segments were sampled from five intact and six bulbectomized mice, respectively. Multiple identical symbols represent multiple parallel LFP measurements (with up to five electrodes in the whisker barrel cortex) or multiple LFP samples from the same recording site in one mouse. Each symbols position along the x axis is determined by the average respiratory rate during the corresponding 50-s segment. (d) Summary of the data shown in c. White and black box-and-whisker plots represent the means (ticks inside the boxes), the 1st and 3rd quartiles (bottom and top ends of the boxes) and the extents of the data (whiskers) for the white and black data points in c, respectively.