Figure 2.

Experimental design and basic phenomena. A‐B. Adaptation is measured at four levels in the circuits. Two of the signals are obtained from ORN recordings and are shown in panel A. The other two signals are obtained from PN recordings and shown in panel B. (A) ORN responses were recorded with a sharp electrode inserted into the pb1 sensilla. pb1 sensilla in the Or71a mutants have one functional ORN, pb1A, and one nonfunctional, pb1B. Sample trace shows the response of a pb1A ORN to a pulse of 2‐butanone ([10⁻⁶]). Response to odor consists of a slow signal, as well as, spikes. Smoothing isolated the slow signal, which is a measure of the transduction step. Spikes are measured separately. (B) PN responses were recorded with whole‐cell patch‐clamp and data were analyzed similarly to the ORN. (C) The background odor intensity is color coded and indicated at the top right of the panel. Top traces show a schematic of the odor stimulus command. Bottom traces, show ORN and PN spike responses to a 10⁻⁴ pulse during a range of background odor intensities. Responses were averaged across trials and cells. ORN spikes are an average of (N = 4–11 trials) and (N = 5–6 cells). PN spikes are averaged across (N = 3–10 trials) and (N = 5–7 cells).