Figure 1.

Pulse stimulation of OSNs with Mix B or IF. (A) Pulse stimulation with an odor mixture increased the response. The membrane current was recorded from a single OSN at different voltages from −100 mV to +100 mV in 20-mV increments. Each voltage step lasted for 4.5 s, and Mix B was applied to the OSN for 1.5 s. There was a 20-s interval between the two recordings. Only the current trace recorded at −100 mV is shown. The black bar above the trace represents the application time of Mix B. The traces of the two repetitive recordings are numbered in the order in which they were collected. (B) Pulsed increases of [cAMP]_i mimicked the odor-elicited potentiation. The membrane currents were recorded from the OSN using the 11-step protocol. In this and all subsequent figures, the black bar above the trace represents the stimulation time of IF. The top traces show the outward currents elicited by IF at +100 mV, while the bottom traces show the inward currents elicited by IF at −100 mV. The first recording of the OSN is marked 1, and the subsequent recordings are numbered in order collected. There was a 1-s interval between the recordings. The inward and outward current elicited by IF increased with repetitive stimulation. The magnitude of inward current or outward current was measured as the current from the peak to the baseline (dashed line). (C) The pulse stimulation of IF changed the shape of the current–voltage relationship. Pulse stimulation with IF-potentiated current response was largest at more negative potentials. The peak inward and outward current elicited by IF was plotted at each voltage. In the first recording set (Recording 1), IF elicited the largest inward current at −60 mV. In the subsequent recordings, IF elicited the largest inward current at −100 mV. The magnitude of the IF response increased at the more negative and more positive potentials with each repeat.