Current response and fluorescence intensity under scan mode. (A) Scheme of olfactory transduction and experimental procedures. (B) Photomicrograph of a single ORC. The white square shows the ROI area where UV stimulation was applied (stimulus ROI). Fluo-4 fluorescence was obtained from a much larger area in the experiment, but only data from the UV stimulus region are illustrated. (C) The current response to UV stimulation. The downward deflection of the upper trace indicates the period of UV stimulation. Duration: 2.22 s. This value represents the time needed for the raster scan of the ROI area. The actual UV application to the cilium comprises repetitive steps (Takeuchi and Kurahashi, 2008). (D) Fluorescence images. Left, before UV application; middle, during UV application; right, after UV application. Scaling Y, 0.09 µm. Scan speed, 2.22 s/scan. The intervals between image scan initiations were 7.04 s. Line sum, 4. Note that the increase in fluorescence is not obvious at the beginning of irradiation but becomes more noticeable in the lower region of the middle image. Three images correspond to the second, third, and fourth data points in F. (E) Positions of five analysis ROIs (red circles, 0.23 µm in diameter) used for fluorescence measurements. (F) Change in ΔF/F₀. Plots were obtained from the five analysis ROIs indicated in E. Error bars show the SD from those data.