Figure 6: Preplay is abolished when events are decoded with shuffled cell identities but is preserved if cell identities are shuffled only within clusters.

We decoded the population burst events from the fiducial parameter set simulations after randomly shuffling cell identities in three different manners (a-c, 25 replicates for each condition) and compared the resulting preplay statistics to the unshuffled result (red line). (a) Randomly shuffling cell identities results in median preplay correlation shifts near zero (top, 100^th percentile of shuffles), with p-values distributed approximately uniformly (bottom, 0^th percentile of shuffles). (b) Randomly shuffling cell identities within clusters reduces the magnitude of the median preplay correlation shifts (top, 100^th percentile of shuffles) but preserves the statistical significance of preplay (bottom, 0^th percentile of shuffles). (c) Randomly shuffling cell identities within clusters for only cells that belong to a single cluster results in median preplay correlation shifts that are similar to the unshuffled result (top, 36^th percentile of shuffles) and are all statistically significant (bottom, 12^th percentile of shuffles).