Odor-induced Ca2+-activity is maintained all along the 2-min odor application, and is sensitive to the frequency of the odor-repetition. (A) Mean of the amplitude (+/-SEM) of the response (photons/s) versus time, of the Ca2+-induced response evoked by a long odor application (2 min) (represented by the colored bar below the abscissa) for the three tested odors (n = 6 flies for each odor). Interestingly, we note that the Ca2+-response in the axon terminal is maintained (although it decreases) at least during the 2-min odor application (for each of the three tested odors), but rapidly decreases when the odor application is stopped. (B) Total amount of emitted photons and duration of the response of the 2-min odor application for each odor. The duration of the response is longer than 2 min (Sp = 178 s, Ci = 141 s, Oct = 149 s). C) Amplitude of the response (photons/s) of a representative fly, versus time, of the Ca2+-induced response (within the ROI) evoked by 5 s application of spearmint, citronella, and octanol, repeated 10 times at 1 min-interval. For octanol, we remark that since the duration of the first response is very long (> 60 s), the Ca2+-response of the first odor-application is not yet finished when the second odor application occurs (which likely explains why for the second application, the amplitude is higher than for the first one).