Fig. 5.

Slow modulation of vlPAG GABAergic neuron activity during inter-REM interval. a Average normalized EEG spectrogram (upper) and mean firing rate (z-scored) of significant REM-off vlPAG GABAergic neurons (lower) during two successive REM episodes and the inter-REM interval. Each REM episode and inter-REM interval was temporally compressed to unit length before the firing rates were averaged over multiple episodes/intervals and across GABAergic REM-off neurons (n = 11). Shading, ±s.e.m. b Firing rate (FR, z-scored) during NREM (left) and wake (right) episodes within different segments of the inter-REM interval. Each inter-REM interval was divided into five equally sized bins, and NREM or wake firing rates were averaged within each bin. Each symbol represents the average NREM or wake firing rate of a unit. The average NREM firing rate decreased during the inter-REM period (R = −0.48, P = 2.5 × 10⁻⁴, T(53) = −3.93, linear regression), while the wake activity showed no significant trend (R = −0.04, P = 0.76, T(52) = −0.29). Black line, average firing rate of each bin. c Mean firing rates during the first (light gray) and last (dark gray) NREM episodes of each inter-REM interval. Each NREM episode was temporally compressed to unit duration before the z-scored firing rate was averaged over episodes and across cells. The firing rate during the first NREM period was significantly higher than during the last period (n = 11 units, P = 0.008, T(10) = 3.28, paired t-test). Shading, ±s.e.m. d Mean firing rates during the first (light purple) and last (dark purple) wake episodes of each inter-REM interval. Each wake episode was temporally compressed to unit duration before averaging. e Mean firing rates during all NREM (gray) and wake (purple) episodes. Note that the firing rate decreased during NREM (R = −0.65, P = 2.8 × 10⁻¹⁴, T(108) = −8.78) but increased during wake episodes (R = 0.21, P = 0.027, T(108) = 2.24)