Fig. 4: Antagonistic infraslow and ultradian dynamics across brain areas.
From: Low-dimensional population dynamics in the brainstem gate REM sleep
a, The firing rates of each unit can be approximated by a weighted sum of PC1 and PC2. The scatterplot shows for each unit the two coefficients c1 and c2 for PC1 and PC2 (see formula). b, Firing rates and fit using only PC1 and PC2 for three example neurons, indicated by the arrows and colored crosses in a. The red dashed lines indicate two ISO cycles. c, Activity of different neuron subclasses throughout the ISO cycle. The duration of each ISO cycle was normalized in time and the z-scored activity of each unit was averaged across multiple ISO cycles. c1−c2−, n = 237; c1+c2+, n = 285; c1+c2−, n = 448 units. Shadings indicate the s.e.m. d, Activity of different neuron subclasses during inter-REM interval. Top, heat maps depicting for each subclass the mean activity of individual neurons (rows) throughout the inter-REM interval, with units sorted by their absolute c2 value (|c2|). For time normalization, each inter-REM interval was divided in ten equally long bins, and the z-scored activity of each unit was averaged for each bin across multiple inter-REM intervals. Bottom, average activity for each subclass. c1−c2−, n = 237; c1+c2+, n = 285; c1+c2−, n = 448 units. Shadings indicate the s.e.m. e, Firing rates of different neuron subclasses during NREM (top) and wake (bottom) states across the inter-REM interval. Each inter-REM interval was divided into ten bins, and the NREM or wake activity of each unit was averaged within each bin across multiple inter-REM intervals. c1−c2−, n = 237; c1+c2+, n = 285; c1+c2−, n = 448 units. Shadings indicate the s.e.m. f, Correlation of c1 and c2 with slope during inter-REM. For each unit, we determined the slope at which its firing rates changed throughout inter-REM (Methods) and plotted it against its c1 and c2 value. Dots represent single units. Lines depict regression fits, indicating the mean slope; shadings indicate the 95% CIs around the fitted mean. Linear regression; c1 versus slope: r = 0.40, P = 0.0; c2 versus slope: r = 0.71, P = 0.0; n = 1,160 units. g, Top, schematic illustrating partitioning of inter-REM into early, middle and late sections. Bottom, activity of different neuron subclasses across ISO cycles during early, middle and late inter-REM sections. c1−c2−, n = 237; c1+c2+, n = 285; c1+c2−, n = 448 units. Shadings indicate the s.e.m.
