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. Author manuscript; available in PMC: 2012 Jan 1.
Published in final edited form as: Prog Brain Res. 2011;193:17–38. doi: 10.1016/B978-0-444-53839-0.00002-8

Figure 2. Homeostatic regulation of SWA and slow wave parameters.

Figure 2

(A) Time course of SWA in NREM sleep during the light period. Mean values (n=15 rats, SEM) are plotted for consecutive 3-h intervals. (B) Time course of EEG power spectra in NREM sleep during the light period (same data as in (A). Mean spectra are plotted for consecutive 3-h intervals. Note a progressive shift of the spectral peak towards slower frequencies in the course of the light period. (C) Distribution of the amplitude of slow waves during early and late sleep. Mean values (SEM, n = 15 rats) are plotted as percentage of the total number of waves. Triangles: amplitude ranges where slow wave incidence was higher during early sleep (triangles up) or higher during late sleep (triangles down, p<0.05, Sidak test). (D) Slopes of the 1st and 2nd segment of EEG slow waves in early sleep and late sleep. Mean values, n=15 rats. Asterisk: p<0.05, paired t-test. (E) Near-simultaneously occurring LFP slow waves recorded from layer V of the frontal and parietal cortical areas. Note that the parietal slow wave is delayed relative to the frontal wave. Dotted lines depict slopes of the slow waves. (F) Relationship between the delay between slow waves occurring in the frontal and in the parietal derivation and the corresponding slow wave slopes. One individual rat is shown. Note that slow waves have steepest slopes when they occur synchronously in the two derivations, especially in early sleep.