Fig. 2. Single sensillum recordings from sensillum type 2 (see Fig. 3) containing two olfactory receptor neurons. In spikeamplitude histograms on the right-hand side of recordings, the neurons are distinguished by having different spike amplitudes for large spike amplitude (filled columns) and small spike amplitude (white columns). The figure shows responses to the two major pheromone components (E)-12- and (Z)-12-tetradecenyl acetates (E12- and Z12-14:OAc) at a 10 µg loading. The two neurons, characterized by a large (filled arrowhead) and small (open arrowhead) spike amplitude, respond to E12-14:OAc. The large spiking neuron is also stimulated by Z12-14:OAc. The correctness of the characterizations was corroborated by differential adaptation experiments (see Fig. 5).