Fig. 2: Dopamine responses reflect subjective value on a trial-by-trial basis.

a Peri-event raster and average impulse rate traces for a single dopamine neuron aligned to onset of fractal display. The raster is sorted by reward magnitude level (left) and monkey bid (right). b Correlation of average impulse rates per bin for monkeys’ bids binned by tenths (simple linear regression). c Average traces of impulse rates of all bid-correlated dopamine neurons grouped by reward magnitude (Monkey V, n = 41 neurons). d Average traces of activity of all bid-correlated dopamine neurons grouped by bid quintiles (same neurons as in (c)). e Average normalized impulse rates during the post-event time period shown by the gray box in (c) (box center lines represent median, margins represent 25th and 75th percentiles, whiskers represent the range of all non-outlier data, and “+” points indicate outliers; Kruskal–Wallis test, Tukey–Kramer multiple comparison test). f Mean normalized impulse rates shown in (d) with fitted regression lines (simple linear regression; error bars show standard error of the mean). For (e and f), n = 32 and n = 41 neurons for Monkeys U and V, respectively. Note that all analyses concerned only the second, value dopamine response component (gray analysis time windows in (a, c, d)), whereas the preceding first, attentional response component varied only inconsistently. Analysis time windows were 180 to 360 for monkey V, and 180 to 340 for monkey U (detailed in “Experimental Procedures”). These windows were used for these and all following analyses.