(a–d) Raster plots for firing of single units on initial (red), blocked (black), upshift (blue), and downshift (green) trials. All raster plots are from the first day of unblocking. Odor onset (On) is indicated by the first vertical line, novel odor onset (Novel) by the second vertical line, and odor offset (Off) by the third. Each tick represents a spike. Average activity across all trials is plotted by odor (bottom) showing a) Selective firing to the upshift odor, b) Putative predictive firing to the upshift and downshift odors, c) Putative salience firing to all three novel odors but not the initially trained odor, d) Putative value firing, exhibiting a monotonic firing pattern. (e) Mean neural activity (novel odor epoch - ITI) for the upshift-responsive population (n=60) is plotted. Line colors as in raster plots; shaded areas indicate standard error of mean. ANOVA with bin and odor as factors found significant effects of bin, odor, and the bin x odor interaction (F59,14160=19.81, F3, 14160=52.47, F177, 14160=1.46, ps<0.001). ANOVA restricted to the novel odor period with odor and time (1st 500 ms vs. 2nd 500 ms, shown in upper right inset) as factors found a main effect of odor and time (F3,472=13.93, F1,472 = 10.89, ps<0.01). At both times there was no difference between blocked and downshift firing rates. (f) Baseline-normalized firing to the upshift cue for the upshift-responsive population on the first 10 trials of the first unblocking day (n = 33). Firing was calculated in a 150 ms sliding window for each 50-ms bin moving away from novel odor onset. The firing rate over ITI was then plotted, with dark red bins indicating maximal firing to the upshift cue and blue indicating minimal firing. Heat plot values are shown on right of heat plot. (g) The significance of the increased firing to the upshift cue was determined by performing a one-tailed t-test, comparing increases in firing to 0, using a significance of p<0.001 and a sliding window as in Figure 2f. Black bins indicate significant elevations in firing to the upshift cue. (h–k) Mean neural activity (novel odor epoch - ITI) for different upshift-responsive populations is plotted as in Figure 2d for h) Cells that respond only to the upshift cue over baseline, i) Cells that respond to the upshift and downshift cues over baseline but do not respond to the blocked cue. j) Cells that respond to the novel odor cues but not the initially trained cue over baseline. k) Cells whose signal increases monotonically with increasing reward amount. (l) Pie chart of the proportion of upshift-responsive neurons in each category. (m–p) Scatter plots of blocked-cue and baseline-normalized upshift and downshift firing rate for m) Upshift only n) Predictive o) Salience p) Value populations. (q) Classification accuracy for all cells that respond only to the upshift cue on day 1. Chance is indicated with a dashed red line. Classification accuracy significance above chance is indicated above time bins in a color matching the trial type. *p<0.05, xp<0.01. Error bars indicate SEM.