Fig. 1

Performance of male C57BL/6 mice in the unrestricted FR5 schedule a. The total number of trials completed (one-way ANOVA; F = 7.48, df = 2,11, p < 0.01). b. Target touches, the total number of responses to the correct touchscreen response location (one-way ANOVA; F = 7.47, df = 2,11, p < 0.01). c. Blank touches, responses to incorrect touchscreen locations (n.s.) d. Reward collection latency, the time between reward delivery to the magazine and reward collection by the animal (n.s.). e-f. Rate of IR beam breaks in the front and rear areas of the touchscreen chamber (n.s.). LM, low-fat milk; SM, strawberry-flavored milk; PM, plain white milk. Note that SM and PM are isocaloric (65 kcal/100 mL) but have different sugar and fat compositions. LM is low calorie (40 kcal/100 mL). n = 3–7 per group. n.s., not significant. *p < 0.05; **p < 0.01 in Tukey’s post hoc comparison