ORN first-spike latency for single odorants and mixtures.

(a) The average first-spike latency predicted by our model ORNs decreases with the number of components in the odor stimulus. This effect is most pronounced when the stimulus concentration is low. The shorter first-spike latency for mixtures cannot be fully explained by the higher number of odor molecules in stimuli with more components compared to their counterparts with less components at the same concentration, since the latency for binary mixtures (dark cyan) is lower than that for a single odorant with doubled concentration (dashed line). Please note that all odor-receptor combinations with latency greater 100ms were taken to be 100ms when we calculate the average latency. (b) Example voltage traces obtained from recordings from an ab2 sensillum stimulated bymethyl butyrate, ethyl acetate and their mixture. The traces are filtered by a 100 to 3000 Hz bandpass. Large spikes belong to the OR59b-expressing ORN. (c) Recorded first spike latencies from Drosophila ORNs for binary mixtures and average latencies of their constituent components at doubled concentration, for 73 different animal-odor-receptor combinations. For the majority combinations (70 out of 73), the latency for mixtures is smaller than the average latency for the two components on their own. (d) Same as (c) but the comparison is made between mixtures and their constituent components with shorter latency at doubled concentration. The latency for mixtures is still smaller for most combinations (57 out of 73). The total number of measuremens for black/gray/red/blue is 17/20/21/15.