Examples of Kenyon cell (KC) claws fluorescence levels in response to 4-methylcyclohexanol (Mch) and 3-octanol (Oct) in control animals (A, APL ON) or in flies where the output from APL was blocked (C, APL OFF). The genotype used is APLi-GAL4> UAS TeTx, UAS-mCherry; MB247-homer::GCaMP3. Scale bar = 10 μm. (B) The average activity peak in KC claws was similar when APL was active (APL ON, p = 0.949), but was highly variable in the absence of APL output (APL OFF, p = 0.0003 (***)). n = 10, two-way ANOVA with Tukey’s multiple comparisons. (D) The number of odour-responding ROIs was comparable in the presence of active APL (APL ON, p = 0.995) and it was slightly increased in the absence of APL output (APL OFF, p = 0.047 (*)). n = 10, p = 0.047, two-way ANOVA with Tukey’s multiple comparisons. (E) Frequency distribution of activity peaks among microglomeruli (MGs) responding to a particular odour in the presence of APL inhibition. The two populations are highly overlapping, as in Figure 3G. n = 10, p = 0.0533, Kolmogorov-Smirnov test. (F) In the absence of APL activity, the distribution of MGs responding to Oct shifted towards higher values, resembling presynaptic PN boutons data shown in Figure 3C. n = 10, p < 0.0001 (***), Kolmogorov-Smirnov test. Odours were diluted 1:100, bars indicate means.