Extended Figure 4. Neurons active during Aversive learning selectively participate in burst events offline.
A) Example of a burst event quantified in this figure. The top trace represents the z-scored mean population activity within one of the offline recordings. Three timepoints were chosen (overlaid in circles), the middle representing the peak of a burst event, and the timepoints to its left and right representing t−2sec and t+2sec from the peak, respectively. The bottom three matrices represent binarized spatial footprints depicting the spatial footprints of the cells sufficiently active to participate in a burst (z>2). The matrices represent the timepoints of the three datapoints above it, ordered by time.
B) Representative process of extracting ensemble participations (one mouse example). The left is an example burst period, with the rows in the heatmap representing the activity of the recorded cells during that session, binarized by z>2 and color-coded by whether they were previously active during Aversive learning (Aversive ensemble, blue) or if they were not previously active (Remaining ensemble, grey). The black trace above represents the z-scored mean population activity during this period, demonstrating a brief burst in activity accompanied by participation by a significant fraction of neurons. On the right is an example non-burst period, where mean population activity remains below threshold.
C) The burst event frequency decreased across the hour.
D) A larger fraction of the Aversive ensemble vs the Remaining ensemble participated in each burst event (left) (t7 = 3.68, p = 0.0079).
E) The top matrix is every reactivation event stacked and centered on time t=0. The bottom is the average mean population activity around each burst event. There is no periodicity to when these burst events occur. Note that an example mouse is shown here but all mice showed this effect.
F) The top matrix is the locomotion of an example mouse during each burst event. The bottom is the mean locomotion around burst events. Mice showed a robust and brief slowing down ~1sec before each burst event, before increasing locomotion back up ~2sec later. Note that an example mouse is shown here but all mice showed this effect.