Fig. 8: OMP-deficient mice lose olfactory sensitivity to background odours.

a The sucrose preference measurement by a licking metre. b Preference of mice for sucrose. Licking was counted for 5 s from the first lick. c Summary of licks during 5 s. Mean ± s.d. d Training paradigm to associate a sucrose reward with the limonene-(+) odour. A swab containing L( + ) was presented with a sucrose solution. e, f Schemes of 10% L( + )-odour-source searching associated with a sucrose reward in (e) room air and (f) an atmosphere with a 1% L( + ) background odour. g, h Representative heatmaps of the times mice spent reaching and licking the correct spout with the sucrose reward. Bottles with or without a reward were switched in different sessions (g, f). i Time to the first correct licking of the reward bottle. j The number of wrong licks of the empty bottle before the first correct lick. Means are shown in black bars in (i, j). n = 5 each for WT, Het and KO in (c, i, j). *P < 0.05; **P < 0.01; ***P < 0.001. Statistics: room air; i one-way ANOVA and post hoc Bonferroni test; F(3, 12) = 27.26, P < 0.0001 and P_{WT vs Het} > 0.999, P_{WT vs KO} < 0.0001, P_{Het vs KO} = 0.0002. j Kruskal–Wallis test; P = 0.018. The Mann–Whitney U test for further comparison; P_{WT vs Het} = 0.42, P_{WT vs KO} = 0.023, P_{Het vs KO} = 0.053. Background odour; i one-way ANOVA and post hoc Bonferroni test; F(3, 12) = 5.85, P = 0.017 and P_{WT vs Het} = 0.4, P_{WT vs KO} = 0.015, P_{Het vs KO} = 0.29. j Kruskal–Wallis test; P = 0.0013. Mann–Whitney U test; P_{WT vs Het} = 0.0056, P_{WT vs KO} = 0.0071, P_{Het vs KO} = 0.0092. Pre/post comparison; i one-sided T test without (pre) and with (post) a background odour; P_{WT, pre/post} = 0.015, P_{Het, pre/post} = 0.0035, P_{KO, pre/post} = 0.0099. j Mann–Whitney U test; P_{WT, pre/post} = not determined (nd), P_{Het, pre/post} = 0.01, P_{KO, pre/post} = 0.01.