Extended Data Figure 9: PCA of population trajectories in fear versus neutral contexts.

a, PCA of ΔF/F traces of all active cells for mouse 2, performed separately for fear and neutral contexts. Population trajectories in the fear context take large, nearly orthogonal, deviations from the centre, while neutral context trajectories remain close to the origin. b, Three-dimensional reconstruction of the neuronal population showing that neurons participating in each synchronous event (red cells (t = 39), green circles (t = 92), blue circles (t = 200)) are largely non-overlapping and anatomically homogenously distributed throughout the volume. There are, however, a small fraction of neurons that participate in all three events (black circles). c, d, Data are shown for another representative mouse. Similar results were seen in all other mice. e, The ΔF/F traces for a randomly selected set of 30 neurons participating in each of three events are shown, with the greatest amount of overlap seen between t = 65 and t = 210. Scale bars: 400% ΔF/F, 20 s.