Extended Data Fig. 4: Latent inhibition: Dopamine responses to non-pre-exposed and pre-exposed stimuli do not differ in the absence of latent inhibition and converge following extensive experience.

a, Dopamine responses did not differ between the CS+ and pre-exposed CS+ for the animals that did not show latent inhibition. b, The peak heights (two-sided nested ANOVA, F_{(1, 21)} = 0.61, P = 0.4449, n = 30 presentations; n = 5 mice), c, the time to return to baseline (two-sided nested ANOVA, F_{(1, 21)} = 0.30, P = 0.5888, n = 30 presentations; n = 5 mice) and d, tau were not different between the CS+ and pre-exposed CS+ (two-sided nested ANOVA, F_{(1, 21)} = 0.60, P = 0.4467, n = 30 presentations; n = 5 mice). e, In the mice that showed latent inhibition, the behavioral and dopamine differences disappeared. f, Freezing responses to the pre-exposed CS+, non-pre-exposed CS+ (CS+) and non-pre-exposed CS− (CS−) were measured on session 2 of a two session fear conditioning paradigm (RM ANOVA pre-exposure main effect, F_{(1.466,5.863)} = 19.99, P = 0.0032), the difference between the CS+ and pre-exposed CS+ disappeared on the second conditioning session (Tukey post-hoc, P = 0.9979). Both the CS+ (Tukey post-hoc, P = 0.0034) and the pre-exposed CS+ (Tukey post-hoc, P = 0.0037) yielded a stronger freezing response compared to the CS−. g, Averaged dopamine responses to the CS+ and pre-exposed CS+ during session 2 over all trials. h, Dopamine responses did not differ between the CS+ and pre-exposed CS+ (nested ANOVA, F_{(1, 54)} = 0.42, P = 0.8901, n = 30 presentations; n = 5 mice). i, The time to return to baseline was not different (nested ANOVA, F_{(1, 54)} = 0.07, P = 0.7864, n = 30 presentations; n = 5 mice). j, Tau is another measure of dopamine clearance and is defined by the time in seconds for the signal to return to 2/3 of peak height. Tau was not different between the CS+ and pre-exposed CS+ (unpaired t-test, t₅₈ = 0.27, P = 0.78, n = 30 presentations; n = 5 mice). In the absence of the latent inhibition effect, dopamine response to the pre-exposed and novel CS+ do not differ. Data represented as mean ± s.e.m. ** P < 0.01, ns = not significant.