Figure 6.
Putative replay frames are associated with hippocampal activity. (a,c) Examples of automatically detected hippocampal ripples (in orange squares, which covers 125 ms) and the surrounding LFP from subjects 2, 3, and 5, respectively. (d) Hippocampal LFP average triggered on 1st cortical HG peaks of matched Events (exact matches, no shuffle thresholds). (e) Aggregate time-frequency plot with all three subjects (470 randomly selected trials each); broadband hippocampal activity increases for ~1000 ms during matched Events. Power from 1–200 Hz (linear scale), with green mask for p > 0.05 (two-tailed bootstrap) from baseline period (−1500 ms to −1000 ms). (f,g) Time-frequency analysis of automatically detected ripples from posterior hippocampus shows power in the ripple frequency range (70–100 Hz). Vertical solid lines/horizontal dash lines that go across panels indicate shared X- or Y- axes across subplots, respectively. (h,i) Ripple occurrence rates become elevated near and after Motif-Event match peaks. The black horizontal dash line indicates median ripple rate, and the orange horizontal dash line indicates the 99th percentile. Time windows that show significance are described here as [start,end] in milliseconds, where negative/positive values refer to the temporal distance from trigger times: p = 0.039 at [−2000, 2000] and p < 0.001 at [0, 4000] for Sub. 5; p = 0.013 at [−2000, 2000], p = 0.0446 at [0, 4000], p = 0.039 at [1600, 2000] and at [2400, 2800] for Sub. 3 (FDR-corrected permutation tests). Orange boxes: significant time stretches. Due to the long time-base, only the first HG peak from a given Event would be used in this analysis. All Events are from the first Sleep-Post period. Similar effects were found for the second period (not shown).