Fig. 1. The pheromone response is characterized by six parameters. (A) An unfiltered response to a 50 ms stimulus of 1 µg bombykal (BAL). Action potentials are superimposed on the negative deflection of the transepithelial potential, the sensillar potential (SP). The maximal SP amplitude is measured between the baseline before the response and the negative peak during the response. The half-time of the rising phase (t_{1/2 rise}) is determined between the onset of the SP and the time the potential has reached 50% of SP. The half-time of the decline phase (t_{1/2 decline}) is measured between the end of the response, which at short stimulus duration coincides with the negative peak, and the time the potential has decayed to 50% SP. For the analysis of all parameters describing the SP, the responses are lowpass-filtered at 50 Hz or 70 Hz. (B) The initial phase of the response at an enlarged time scale. The initial slope is determined by dividing 0.5xSP by t_{1/2 rise}. The action potential (AP) latency is measured between the onset of the SP and the peak of the first AP. (C) For the analysis of APs, the lowpass-filtered response is subtracted from the original trace, yielding a straight baseline. The initial AP frequency is computed from the first five interspike intervals.