VP neurons encode reward-contingency more robustly than OTD1 or OTD2 neurons.
(A) Heatmap of odor-evoked activities in OTD1, OTD2, and VP neurons from day 6 of imaging. The fluorescence measurements from each neuron were averaged over trials, Z-scored, then pooled for hierarchical clustering. Neurons are grouped by similarity, with the dendrogram shown on the right and a raster plot on the left indicating which region a given neuron is from. Horizontal white lines demarcate the boundaries between the 6 clusters. Odor delivered at 0-2 seconds marked by vertical red lines and US delivery is marked by arrowheads. From left to right, the columns represent neural responses to sucrose-paired ketone and terpene, control ketone and terpene, and airpuff-paired ketone and terpene (SK, ST, XK, XT, PK, PT). (B) Average Z-scored activity of each cluster to each of the 6 odors on day 6 of imaging. Yellow bar indicates 2-seconds of odor exposure. (C) The distribution of clusters by population. (D) Percentage of total neurons that were significantly excited or inhibited by each odor (Bonferroni-adjusted FDR < 0.05) as a function of time relative to odor. Bar represents the mean across biological replicates and x’s mark individual animals. (E) Bar graph showing % of neurons from each population that are responsive to both sucrose-paired odors in the same direction (left), responsive to only a single odor (middle), or responsive to at least 3 odors (right). (F) Scatterplot comparing the magnitudes of SK responses (ΔΔSK) to ST responses (ΔΔST). The dotted line represents the hypothetical scenario where ΔΔSK = ΔΔST. For each population, the R2 value of the 2-d distribution compared to the ΔΔSK = ΔΔST line is reported. (G) Same as F but comparing ΔΔSK to ΔΔXK. (H) Lineplot showing the % of neurons from each population where the difference between ΔΔSK and ΔΔXK is lower than that between ΔΔSK and ΔΔST. (I) Bargraph showing % of neurons whose responses to {SK vs. XK} can be discriminated by a linear classifier with auROC>0.75. (J) Same as H but for {SK vs ST}. (K) Schematic representation of 4 possible categories for a joint-distribution of {SK vs. XK} and {SK vs. ST} auROC values. Identity-encoding neurons could be in any quadrant other than the bottom-left whereas valence-encoding neurons should be in the bottom-right quadrant. (L) Scatterplot of each neuron’s auROC value for {SK vs. XK} on the x-axis and {SK vs. ST} on the y-axis on days 1, 3 and 6 of imaging. (M) Stacked bar graph showing the distribution of neurons from each population that fall into each of the 4 quadrants across the 3 different imaging days.