Figure 1.

Calcium signals from m-ALT and l-ALT PNs to pheromonal odorants. A, Dual olfactory pathway of the honey bee brain (adapted from Carcaud et al., 2012). Odorant molecules are detected by ORNs on the antenna, forming the antennal nerve (AN) and project to the AL. Then, PNs convey information to the MB and the LH via two main tracts: the m-ALT (magenta) and the l-ALT (green). Injection locations are shown as black dots (inj1 and inj2). OL, Optical lobe. B, Retrograde staining of l-ALT PNs (left) and m-ALT PNs (right) innervating, respectively, ventral and dorsal AL glomeruli. Z-projection of optical slices at the indicated depths. C, Odor-induced calcium signals in the AL at room temperature (∼25°C, left) or at hive temperature (35°C, right), for l-ALT PNs to QMP (top) and for m-ALT PNs to methyl linolenate (bottom). Relative fluorescence changes (ΔR/R%) are presented in a false-color code, from dark blue to red. D, Time course of ΔR/R% during a 20 s 5 Hz recording for l-ALT (top) and m-ALT PNs (bottom). The signals from different glomeruli (1–4) located as indicated in C are shown for room T° (dashed lines) and hive T° (solid lines).