FIG. 4.

Quantification of the responses of PNs in glomeruli adjacent to or 1–2 glomeruli away from the MGC or distant to the MGC and G35 to stimulation with the sex-pheromone blend (A and B) and Z3-6:OAc (C and D). A and C: the net number of spikes in a 1-s period postantennal stimulation. B–D: the amplitude of the odor-evoked change in membrane potential. ○, the average response (control-subtracted for clarity) of each PN to illustrate the response variability. •, the average response across PNs. The net number of spikes and the change in membrane potential evoked by the pheromone blend were statistically different from those evoked by the cyclohexane solvent-control stimulus in PNs in glomeruli both nearby and distant to the MGC (A and B, *, Wilcoxon matched pairs tests, n = 11 and 14, P < 0.05). The responses evoked by Z3-6:OAc were statistically different from that to the mineral-oil control stimulus only in PNs in glomeruli distant from the MGC and G35 (C and D, *; Wilcoxon matched pairs tests; G35 PNs were not included in this analysis because Z3-6:OAc evokes a strong excitatory response in these PNs). PNs were stimulated with pheromone blend (200 or 500 ng; duration: 200 or 500 ms), the cyclohexane control (200 or 500 ms), Z3-6:OAc (1:100 vol/vol in most cases; G35 PNs were stimulated with 1:1,000 or 1:10,000 vol/vol; duration = 200 ms), and the mineral oil control (200 ms; see methods for an explanation of the different concentration/stimulus duration used). These results indicate that many PNs in sexually isomorphic glomeruli receive inhibitory input from the MGC regardless of their position, and that PNs in distant glomeruli receive inhibitory input from G35 and/or other Z3-6:OAc activated glomeruli.