Fig. 3

Population summary of the spatial correlation of the activity maps and signal size vs. odor concentration. a The mean spatial correlation of each frame subtraction map with the map from the other three concentrations. The activity maps of the output (right) are more similar to each other than are the activity maps of the input (left). This summary includes 14 measurements from 13 preparations (responses to two different odorants were measured in one preparation). b Normalized signal size vs. odorant concentration for 15 measurements in 14 preparations (thin lines, two different odor responses were measured in one of the preparations). The average of the 15 measurements is shown as the thick lines. The input signals (black) decline much more rapidly as the odor concentration is reduced. In same hemi-bulb preparations, all activated glomeruli that could be identified for both input and output were included. In opposite bulb preparations, input and output glomeruli were counted if they were activated by 1.83% of saturated vapor. Panel a includes 13 measurements using methyl valerate and 1 using isoamyl acetate. Panel b includes 1 measurement using ethyl tiglate, 13 using methyl valerate, and 1 using isoamyl acetate. The results from the different odorants were not qualitatively different. The error bars represent s.e.m., **p < 0.005. A repeated measures ANOVA and Wilcoxon rank sum test were used for the statistical analysis. Detailed experimental and statistical information for panels a and b are included in Supplementary Tables 1 and 2, respectively