Figure 3.
Mixture suppression is more frequent in PNs than in OSNs. A, Example of OSN responses to 1-butanol (B), isopentyl acetate (I), propionic acid (P), all binary mixtures (BI, PI, PB), and the ternary mixture (BPI). The mask over the left AL shows the position of eight identified glomeruli. B, Example of PN responses to the same odors as in A. The mask over the left AL shows the position of eight identified glomeruli. C, Amplitude of median responses to B, I, P, all binary mixtures and the ternary mixture (BI, PI, PB, and BPI) (top row), and to 2-heptanone (N), 1-hexanol (X), propionic acid (P), all binary mixtures (NX, PX, NP) and the ternary mixture (PNX) (bottom row). Note that some odors elicit negative responses in some glomeruli. Left, OSN (n = 9); right, PN (n = 10–15). D, Interaction index (lower bound − response to the mixture, where the lower bound is the response to the best component for the corresponding mixture) for OSNs and PNs. Orange bars indicate cases in which the lower bound was significantly different from the response to the mixture (Wilcoxon signed rank test, p < 0.05) indicating significant inhibitory interactions. Yellow bars indicate cases in which no significant difference was found between the lower bound and the mixture (Wilcoxon signed rank test, p > 0.05). White bars indicate cases in which at least one of the components evoked a negative response (these cases were excluded from the quantitative analysis) (see Results). Significant interaction indices <0 indicate cases in which mixture suppression can be excluded. Note that mixture synergism was not tested in this experiment. Left, OSN; right, PN.