(A) Summary of time spent in different sides of a modified place preference chamber over five consecutive days in which mice had complete freedom of movement (n = 6; repeated measures ANOVA, significant interaction, F(4,40) = 24.6, P < 0.01; post hoc test of room effect on day one, p < 0.01). During the three test sessions, vHipp axons in the NAc were optically activated whenever mice entered and remained in the ChR2-paired side of the chamber. (B) Summary of instantaneous room exit probabilities each day in the place preference chamber (n = 6; repeated measures ANOVA, significant interaction, F(4,40) = 51.7, P < 0.05; post hoc test of room effect on days two and three, p < 0.01). See also Figure S6. (C) Cumulative-activity graph of nose pokes made in the first behavioral session to obtain optical stimulation of vHipp axons in the NAc (n = 9). Solid lines represent the mean and dashed lines are ± SEM. (D) Summary of active and inactive nose poking behavior in ChR2 and EYFP control mice made during the first behavioral session (n = 9 and 6 for ChR2 and EYFP groups, respectively).