Figure 4. Conditioning with odor and TH-GAL4+ dopaminergic neuron stimulation yielded discrete facilitation in the MB γ lobe.

(A) Confocal images of GCaMP fluorescence from a TH-GAL4>UAS-TRPA1, MB-GCaMP3 fly (heterozygous for all transgenes) in vivo. The plane of section shows the β and γ lobes of the MB, with corresponding regions of interest outlined.

(B) Confocal image as in panel (A), with a z plane showing the α tip (dashed outline).

(C) Confocal image as in panel (A), with a z plane showing the α’ tip (dashed outline).

(D) Temperature (mean ± S.E.M.) measured in the bath adjacent to the fly’s head during forward and backward conditioning. The 30-s odor delivery time is superimposed.

(E) Pseudocolor images of the odor responses in the β and γ lobes before and after conditioning from a representative fly using the TH-GAL4 driver. Scale bar = 10 μm.

(F) Pseudocolor images of the odor responses in the α tip before and after conditioning from a representative fly. Scale bar = 10 μm.

(G) GCaMP responses (mean ± S.E.M.) to odor for the time points measured. The odor presentations immediately before and after conditioning are marked “pre” and “post”. The scale matches panel (H). Odor presentations were spaced 5 min apart (5′).

(H) Comparison of pre- and post- conditioning odor responses for several genotypes, conditioning paradigms, and MB regions (n ≥ 10). *p < 0.05 (Mann-Whitney).

(I) The post / pre odor response ratio for all genotypes, conditioning paradigms, and MB regions (n ≥ 10). There was a significant effect across groups (p < 0.001; Kruskal-Wallis). *p<0.05 (Mann-Whitney); n.s.: not significant. In the legend below the figure, Sig. Δ indicates significant change in odor-evoked ΔF/F following conditioning within each group, with direction indicated by arrow (Wilcoxon signed-rank tests; p < 0.05). F: forward, B: backward, c1: control 1 (no heat), c2: control 2 (no GAL4), c3: control 3 (no TRPA1), us: upper stalk, ls: lower stalk, hl: heel.