Extended Data Fig. 8: Dopamine release in NAcLat, but not NAcMed, encodes negative RPE.
From: State and rate-of-change encoding in parallel mesoaccumbal dopamine pathways
(a) Graphs showing licking behavior of a representative sample animal during the task. Note that licking generally started ~500 ms after CS+ onset with only minimal variability. Inset shows schematic of experimental design: Head fixed mice were trained on a behavioral assay, in which the presence of a CS+ predicted the availability of a reward (3 μl of a 1% sucrose solution). The reward was delivered to the animal after one single lick (that is, it assumes minimal effort to the animal to obtain a reward). After training, mice were subjected to a session in which 10% of the trials were not rewarded (omission trials). DA release was measured simultaneously in the NAcLat and NAcMed using dLight1.2. (b) Top: Heatmaps showing auROC normalized dLight responses in the NAcLat and NAcMed for all animals (n = 9 mice) in standard trials in which reward delivery occurred after the first lick during CS+ presentation. Bottom: mean DA response in NAcLat (blue) and NAcMed (orange) as well as the mean lick rate (dashed line) for all mice. Note that NAcLat DA release tracks CS+ onset and reward delivery, while NAcMed DA tracks licking behavior, including reward consumption. (c) Same as in panel (b) but for omission trials in which no reward was delivered. Note that NAcMed DA release returns to baseline concurrent with the termination of licking behavior. Conversely, NAcLat DA release showed a negative deflection below baseline level during reward omission, which reflects a negative RPE. (d) Quantification (box plot, median and quantiles) of panels (b) and (c). Significance was calculated by means of a two-sided Students t-test; ***P < 0.001, n = 9 mice. All data, except panel (d), are represented as mean ± SEM (shading).
