Fig. 4.

Anatomically standardized contour charts illustrate the responses of mice (top row) and rats (bottom row) to homologous series of (A) aliphatic acids and (B) aldehydes. Lines are superimposed on charts in A to show the gradual ventral progression of uptake with increasing carbon number in the dorsomedial acid-responsive domain in rats. In mice, centroids of uptake in this domain did not differ significantly with carbon number, the average response to caproic acid being somewhat more ventral than the almost completely overlapping responses to the three smaller acids. Activity in a more posterior domain (black outline) also shifted in an overlapping progression related to carbon number in rats, but changed in location erratically with carbon number in mice. The black outline in B shows the lateral domain that is principally activated by aldehydes in rats. Uptake in this region progressed rostrally and ventrally with increasing carbon number in rats. In mice, aldehydes activated glomeruli scattered more widely throughout the layer (red outline), and the activated area changed erratically with odorant carbon number. The scale and orientation are the same as for Figure 2. A dorsal-centered version of this figure is available online as Supplementary Figure 4.