FIG. 2.
Quantification of the responses of Toroid-I PNs (left, means ± SE, n = 11 PNs) to stimulation with bombykal (bomb), C15, Z3-6:OAc, and the 2 respective solvent controls (cyclohexane in the case of pheromone components, mineral oil in the case of Z3-6:OAc). A: the net number of spikes in a 1-s period after the onset of antennal stimulation. B: the amplitude of the odor-evoked deflection (negative values indicate hyperpolarization). PNs were stimulated with 20 ng of bombykal (except 1 PN was stimulated with 2 ng), and with 20, 200, or 500 ng of C15 loaded on filter paper. Stimulus duration was 200 ms (except 500 ms in 3 PNs). Asterisks indicate significant differences between C15 and the respective control (Wilcoxon matched pairs tests; *: P < 0.05, ***: P < 0.005). In neither case was the response to Z3-6:OAc statistically different from the response evoked by mineral oil (Wilcoxon matched pairs tests: P > 0.05). C: time course of the responses of Toroid-I PNs. The net number of spikes (means ± SE, n = 8 PNs) during a 1-s period after the odor had reached the antenna was broken down into 20 50-ms bins. First row: net response to stimulation with the C15 (•) and the cyclohexane control; 2nd row: net response to stimulation with Z3-6:OAc 10−2 vol/vol (•) and the mineral oil control. This panel includes only those PNs that were stimulated with 200-ms pulses. *, statistical differences between the response to the odorant and the respective control for each time bin (Wilcoxon matched pair tests, P < 0.05). Note that the response to C15 was statistically different from that to the control in 11 consecutive time bins. The response to Z3-6:OAc was different from the response to the control in only 1 of the 20 time bins, which is the false positive rate expected under a P = 0.05 criterion. These results show that Toroid-I PNs do not receive inhibitory input from the adjacent G35 glomerulus or any other Z3-6:OAc-activated glomerulus.