(A) VNO slice preparation to analyze individual sensory neurons showing the location of the recording pipette in the basal layer. (B–C) Original ‘loose-seal’ traces from two representative VSNs repetitively responding to a single (B) or all (C) rMUPs. Red bars = stimulation. Stimuli were applied in random order, ISI = 60″. Recordings are representative of VSN population #3 and #11 (panel D), respectively. (D) Summary of 11 distinct populations of neurons observed during extracellular recordings. (E) Representative calcium transients imaged from dissociated VSNs sequentially stimulated with rMUP7 and rMUP19, which only differ by two amino acids (F56V & E140K), followed by a mixture of both MUPs. Colors indicate three distinct populations of VSNs based on response profile. Black bars indicate stimulus application. 3,767 cells imaged, sequentially exposed to all stimuli. (F) Venn diagram quantifying the 3 distinct populations of neurons observed to respond to the two MUP stimuli by calcium imaging, colors correspond to VSN population in panel (E). See also Figure S2.