Figure 3. The rapid development of selective ensemble firings for stimulus associations. A, The distribution of loadings on the PC capturing the network transition after the first aversive stimulus. B, Averaged, 100-ms binned, z-scored FRs in each trial in neurons positive-loadings (≥0.15), negative-loadings (≤−0.15), as well as the remaining, neutral-loadings neurons. Gray bars mask the shock artifact. C, Z-scored, CS-evoked FRs averaged across all positive-loadings or negative-loadings neurons. Each dot depicts the FR in one trial. By fitting an exponential curve (red, blue) to the data, we estimated the number of trials that were required to reach an asymptote. D, Spontaneous FRs (a dot for each neuron, lines show the median) in the block of four different trial types; *p < 0.05, ***p < 0.001, Kruskal–Wallis test, post hoc Dunn's test.