GCaMP Imaging and Odor Stimulation in Drosophila

GCaMP imaging was performed as previously described (Wang et al., 2003 (link); Root et al., 2008 (link)). In odor experiments, a constant airflow of 1 l/min was applied to the antennae via a pipe of 12 mm diameter. Odor onset was controlled by mixing a defined percentage of carrier air with air redirected through odor bottles as previously described (Root et al., 2008 (link); Semmelhack and Wang, 2009 (link)). Nerve stimulation was performed with a glass suction electrode and an S48 stimulator (Grass, Warwick, RI) as previously described (Wang et al., 2003 (link); Root et al., 2008 (link)). Stimulation was 1 ms in duration, 10 V in amplitude, and 16 pulses (Figure 4A) and 45 pulses (Figure 4B) at 100 Hz. Starved flies were starved with water for 16–24 hr.