Fig. 3. Dose/response relationships of four types of olfactory receptor neuron. Values are the number of spikes over 1 s (means ± S.E.M.). (A) Type 1 neurons responded to the pheromone component (R,Z)-6-nonen-2-ol, with the (S)-enantiomer having a 100-fold higher response threshold (N=13). (B) The response pattern of the type 2 neurons is a mirror image of that of the type 1 neurons; they responded to the pheromone component (S,Z)-6-nonen-2-ol (N-11). (C) Type 3 neurons responded to two compounds, (R)-heptan-2-ol and (R,Z)-4-hepten-2-ol, with the response threshold for the respective (S)-enantiomers being approximately 100 times higher (N=5). (D) Type 4 neurons responded to both nine-carbon ketones with a preference for (Z)-6-nonen-2-one over nonan-2-one (N=5). Dose/response curves are not shown for type 5 neurons because these neurons responded only to nonan-2-one and only at high concentrations.