Figure 11.
Long-range power-law correlations in sequences of consecutive θ- and δ-burst durations indicate a dynamical system at criticality. Detrended fluctuation analysis for sequences of θ- and δ-burst durations in control and VLPO-lesioned rats. Burst durations are calculated using a window w = 4 s and threshold Th = 1 on the ratio Rθδ (Fig. 1), and are analyzed separately for 12 h dark/light periods. The rms fluctuation function F(n) is obtained averaging over all rats in the control (a) and VLPO-lesioned group (b), respectively. Log–log plots of F(n) versus the time scale of analysis n, where n is the number of consecutive burst durations, show power-law relations F(n) ∝ nαd over a broad range of scales n. The scaling exponents are significantly larger than 0.5, both in light and dark periods, indicating presence of positive (persistent) long-range correlations in θ-bursts for both control and VLPO-lesioned rats. Similar results are found in sequences of δ-bursts for (c) control and (d) VLPO-lesioned rats. Power-law exponents were obtained from the average rms fluctuation function F(n).