Figure 2.

Examples of Pe1 responses to different chemical compounds (a) benzaldehyde; (b) hexadecylacetate; (c) citral; (d) farnesol; (e) 2-heptanone. Stimulation in a and b was 1 sec using a syringe for fast stimulus onset; in c–e, a glass vessel containing the undiluted odorant was brought into a constant airstream (see Materials and Methods). Because of the latter stimulation procedure, stimulus onset is rather gradual, and both stimulus strength and duration may vary. Fluctuations in spike activity as seen in c–e may thus indicate eddies of odorants.