OLFACTORY CONDITIONING IN THE HONEY-BEE, APIS-MELLIFERA - EFFECTS OF ODOR INTENSITY

Any odor-guided behavior might require generalization and/or discrimin ation over a wide range of odorant intensities. Proboscis extension co nditioning (PEC) and electroantennogram (EAG) assays were used to inve stigate stimulus-intensity dynamics during olfactory processing in the honey bee. Experiments that tested generalization involved conditioni ng to one odorant concentration and either testing with a different od orant or with different concentrations of the same odorant. At low tra ining concentrations, responses to either a novel odorant or to higher concentrations of the same odorant resulted in strong generalization. At higher training concentrations, significantly less generalization was observed to a novel odorant or to lower concentrations of the same odor. EAG analyses indicate that asymmetric generalization could aris e due to long-term adaptation of peripheral receptor neurons. Discrimi nation experiments showed that relatively higher odorant concentration s associated with an appetitive reinforcer could usually be discrimina ted from a lower concentration that was associated with punishment, bu t not vice versa. Although sensory modulation in peripheral (sensory) processes might be sufficient to account for discrimination of a high from a low concentration, discrimination of low from high concentratio ns point to the involvement of central processes. Copyright (C) 1996 E lsevier Science Inc.