Fig. 6: Delta components of locomotion speed are linked to limb stepping cycles and delta-rhythmic neuron spiking.

a Illustration of mouse locomotion with the four limbs labeled. The schematic mouse is adapted from https://doi.org/10.5281/zenodo.3925915. b A single trial example of treadmill speed (Tspeed, blue) and simultaneously measured right hindlimb (RHL) position (black). c Zoom-in of the time window depicted by the green box in b. d Population coherence between treadmill speed and right hindlimb (RHL) position. Yellow dots mark a significant difference between rest and movement (bootstrapping, p < 0.05, n = 4 mice). e RHL and LHL positions aligned to the peak of the delta-frequency component of treadmill speed. f A single trial example of a delta-rhythmic ChI’s membrane voltage (high-pass filtered, black) with spike times (yellow ticks) and accompanying delta-frequency (1–6 Hz) component of treadmill speed (blue). Left, averaged SomArchon fluorescence image of the example neuron. Scale bar, 15 µm. g Normalized firing rate of delta-rhythmic neurons aligned to the peak of the delta-frequency component of treadmill speed. The firing rate is normalized by the mean firing rate of a given neuron (n = 30, only neurons with a minimum of 10 delta-peak triggered windows were included). Gray lines represent individual neurons, the red line is the population average. h Polar histogram and scatter plot of preferred spiking phase of delta-rhythmic neurons (n = 30, neurons with a minimum of 10 delta-peak triggered windows were included) relative to the delta-frequency component of treadmill speed. i, j Same as g, h, but for non-delta neurons (n = 21). All shaded regions around line plots represent the standard error of the mean. Quantifications are visualized as violin plots with the outer shape representing the data kernel density and a box-and-whisker plot (box: interquartile range, whiskers: 1.5x interquartile range, white line: mean). All statistical tests are two-sided. Source data are provided as a Source Data file.