Fig. 6. Dose—response relationships for five of the identified olfactory receptor neurone (ORN) classes. Odorants were presented in increasing dosages from 0.1 ng to 10 µg (x-axis). ORN response to a stimulus is given as the net number of action potentials (number of spikes during 1 s after stimulation minus the number of spikes during 1 s prior to stimulation) minus the net blank response (y-axis). (A) Dose—response curves for the S3A neurone type, (B) S2B type, (C) S1B type, (D) S5A type and (E) S8B type. For details on each ORN type, see Fig. 4. Vertical bars indicate the S.E.M.