Fig. 6. Responses of a salivary duct nerve (SDN) to vanilla or peppermint odour presented to an antenna. (A) Activities of an SDN during 2 s vanilla or peppermint odour stimulations. The responses of the salivary neurones, SN1 (black circle, largest unit) and SN2 (second-largest unit), to vanilla or peppermint odour were very weak and barely detectable in these recordings. (B) Responses of the SDN to vanilla or peppermint odour 30 min after five sets of P+V- differential conditioning trials recorded in the same preparation. SN1 and SN2 exhibited prominent responses to conditioned odour (peppermint), but their responses to control odour (vanilla) were barely detectable. Broken lines indicate the onset and outset of odour stimulation. Vertical bars, 0.2 mV; horizontal bars, 1 s.