Olfactory receptors on the antenna ofPeriplaneta: Response constellations that encode food odors

Summary Electrophysiological methods were used to examine the effectiveness of food odors in stimulating different olfactory receptor types inPeriplaneta.The sense cells occur in certain fixed combinations in particular sensilla, thus defining a physiological sensillum type.The substances used as stimuli were chopped samples of foods of plant and animal origin.Each of the receptor types investigated responded to several kinds of food. No receptor type was observed to respond specifically to one kind only.Because the food odors always contain compounds included in the response spectra of several cell types, it must be assumed that inPeriplaneta the recognition of food odors depends not on the detection of key odors but on the complicated patterns of excitation in the receptors of different types that arise from differences in the combination of unspecific odor components.The components of an odor are not present in constant quantities over a period of time. Accordingly, the measured response profiles of the receptors vary. However, these variations are never so great that a substance strongly effective on one trial is ineffective on another.