Figure 6. AWB and AWC neurons are necessary for aversive olfactory learning following ingestion of E. faecalis.

(A) Schematic of the choice assay (top) and quantification (bottom) of choice index for N2 animals choosing between E. coli and E. faecalis lawns and either free to move for 1 hr (Free to move) or paralyzed upon arrival at a bacterial lawn (Paralyzed). An unpaired t-test between the groups was performed. (B) Schematic of the lid choice assay (top) and quantification of naïve and trained choice index (bottom, left) and learning index (bottom, right) for WT, tax-4(p678), tax-2(p671), tax-2(p694), AWB(−), and AWC(−) animals. To train animals, young adult animals were placed on E. faecalis lawns for 4 hr before the choice assay was performed. For choice index, two-way ANOVA with subsequent comparisons to the naïve and trained WT groups as controls were performed. For learning index, one-way ANOVA with comparison to the WT group as control was performed. (C) Schematic of the paired olfactory choice assay. (D) Quantification of choice index for naïve and trained WT, AWC(−), and AWB(−) animals, choosing between 1:200 benzaldehyde and ethanol. Two-way ANOVA with subsequent comparisons between naïve and trained groups and between WT and neuron ablated animals was performed. (E) Quantification of the learning index for WT, AWC(−), and AWB(−) animals from (D). One-way ANOVA with comparison to the WT group as control was performed. Learning index = (naïve choice index) – (trained choice index).