Fig. 2: Representation of appetitive CS and US throughout Pavlovian conditioning.
A Appetitive Pavlovian conditioning consisted in the association between a cue (conditioned stimulus - CS1; house light and 5-kHz tone) and the delivery of 15 μl of 20% sucrose solution (US1). B Average pokes during different days of Pavlovian conditioning (day 1, day 5 and day 10) of D1-cre mice or C A2A-cre mice, showing that animals increase pokes throughout learning (Friedman test; Dunn’s post hoc). D Heatmaps representing D1-MSN (nday1 = 708; nday5 = 761; nday10 = 699) or G D2-MSN (nday1 = 399; nday5 = 442; nday10 = 480) responses to CS1 (left) and US1 (right) on days 1, 5 and 10. In heatmaps, neurons are aligned by response to the CS. Percentage of responses of E D1-MSNs or H D2-MSNs to CS1 and US1 showing stability in the percentage of CS and US responses in both populations. F Pie chart with the percentage of responses throughout time for D1- or I D2-MSNs, demonstrating that the percentage of CS-US-responsive neurons does not change with learning. J Peri-stimulus time histogram (PSTHs) of cue-excited or L cue-inhibited D1-MSNs or N–P D2-MSNs tracked on different days of learning. K–M Area under the curve (AUCs) of mean cue response (0–3 s from cue onset) for D1- or O–Q D2-MSNs over the days; there is a substantial decrease in the magnitude of response to the cue of CS-excited neurons (and less for cue-inhibited) from day 1 to day 2, suggesting that part of the cue signal is due to novelty (Kruskal–Wallis test). The magnitude of response of CS-excited D2-MSNs during the cue period is higher than in D1-MSNs. Data are presented as mean values +/−SEM. *p < 0.05, **p < 0.01, ***p < 0.001. Source data are provided as a Source Data file. Created in BioRender. Pinto, L. (2024) BioRender.com/p41z755.
