Fig. 4: Odor responses of projection neurons (PNs).

a Representative example of odor responses from six PNs and eight odors. Each panel shows a 5-s recording trace along and above it the raster of spikes from seven trials. The first two PNs are homotypic (belonging to I-AL3 glomerulus), recorded from different animals, while the next four PNs belong to different glomeruli. Scale bar, 10 mV. Gray-shaded region indicates the 1-s odor stimulation period. b Color-coded change in firing rate (spikes/s) evoked by 14 monomolecular odors (some tested at multiple concentrations) and 2 solvents (mineral oil and water) in 144 PNs, each of which was tested with at least five odors. PNs are arranged by glomerular identity, separated by vertical lines. A gray value indicates that the odor was not tested in the PN. c Example of a PN showing a brief response to one odor and a prolonged response to another odor, which continues for 2–3 s beyond the odor stimulation. The bottom panel shows similar delivery profiles for both odors measured with a photo-ionization detector (PID). Scale bars, black: 10 mV; red: 100 mV. d The fraction of odors that elicited a response in a PN; values were averaged for PNs belonging to the same glomerulus. Source data for (b, d) are provided as a Source Data file.