Figure 3.

Intensity invariant ORN response dynamics. a, Raster and PSTH of ab3A response to 500 ms puffs (gray) of increasing concentrations of ethyl acetate (dilutions prepared in paraffin oil as labeled). Dark gray, Standard error on 12 ORNs from 4 flies. b, Black, Peak response of ab3A as a function of ethyl acetate dilutions. Green, Degree of adaptation measured as the peak response minus the adapted response (measured 500 ms after stimulus onset) divided by the peak response. c, PSTHs and PID signals normalized by peak response collapse onto single curves for the odor concentrations arrowed in b. d, Normalized PSTH of single neuron responses are independent of stimulus intensity. Three neurons showed for each odor–receptor combination (2ac, ethyl acetate; 2hept, 2-heptanone; 1but, methyl butyrate; pac, propyl acetate). In each plot, different curves represent the response to different concentrations of the same odorant. e, Variability of normalized responses (see Materials and Methods) calculated across dilutions is smaller or equal than the variability across trials (repetition of the experiment were performed on 12 ORNs of the same type recorded from 3 to 4 animals). Circles correspond to the same odor–receptor combinations as in d, blue triangles correspond to ab3A response to methyl butyrate, methyl acetate, and 1-pentanol, and red triangles correspond to ab2A response to methyl acetate and ethyl acetate.