(A) i. Illustration of the inducible transgene expression in the Omp-IRES-tTA/tetO-Kcnj2-IRES-tauLacZ (Kir2.1) mice. ii. Schematic illustration of genetic silencing olfactory sensory neurons (OSNs) during early postnatal period. (B) i. Dendritic recording of an OSN in Olfr160-IRES-tauGFP (M72-GFP) animal. Superimposed bright field and fluorescent images show a recording pipette attached to the dendritic knob of an M72-GFP OSN. ii. Raster plots showing examples of spontaneous spiking patterns of OSNs from control and Kir2.1-off mice. iii. Distribution of inter-spike interval (ISI) in control (black, neuron n = 16) and Kir2.1-off (red, n = 14) animals. Spike count: Ctrl, 8187; Kir2.1-off, 5076. The ISIs follow lognormal distributions. One-way ANOVA test on average log (ISI) was performed, p=0.45. iv. Bar plot of average firing frequencies of M72 OSNs in control (black) and Kir2.1-off (red) mice. (C) i. Illustration of electro-olfactogram (EOG) recording. ii. Response sample traces (top) and average amplitude (bottom) of C57Bl/6 (B6, n = 189), littermate control (Ctrl, n = 132), and Kir2.1-off mice (n = 104). (D and E) Raster plots of odor port investigation of air, peanut butter (PB, D), and isoamylamine (IAMM, E). Each tick represents an investigation event. Investigations longer and shorter than 1 s are marked by red and black ticks, respectively. Preference index is calculated as the average difference of port investigations between the first two odor epochs and the last air epoch. (F) Bar graph showing preference indices for control (black) and Kir2.1-off (red) mice. Shaded areas indicate innate preference to animals: orange indicates attraction; blue indicates aversion; gray indicates neutral. The gray dashed line indicates the average of preference indices to the five neutral odors. Inlet: enlarged graph showing preference indices to aversive odors. The following odorants were used. Neutral odors, eugenol (EUG, Ctrl n = 9, Kir2.1-off n = 12), heptanal (HPH, Ctrl n = 9, Kir2.1-off n = 9), 2-hexanone (HXO, Ctrl n = 10, Kir2.1-off n = 10), lemon (Ctrl n = 9, Kir2.1-off n = 9), and maple (Ctrl n = 10, Kir2.1-off n = 9); attractive odors, PB (Ctrl n = 10, Kir2.1-off n = 11), female urine (FU, Ctrl n = 10, Kir2.1-off n = 11), and male urine (MU, Ctrl n = 12, Kir2.1-off n = 6); aversive odors, 2-MBA (Ctrl n = 10, Kir2.1-off n = 9), IAMM (Ctrl n = 10, Kir2.1-off n = 9), coyote urine (CU, Ctrl n = 10, Kir2.1-off n = 13), and 2-phenylethylamine (PEA, Ctrl n = 15, Kir2.1-off n = 13). All bar graph data are shown in mean ± SEM. Individual data points are shown as gray dots. One-way ANOVA performed. *, p<0.05; **, p<0.01; ***, p<0.01.