Functional Imaging from Fly Photoreceptors

In this protocol, we describe the procedures for visualizing light-evoked calcium changes in fly visual neurons using two-photon microscopy. Before starting the imaging, the visual stimulation system should be set up properly. To facilitate later data analysis, we recommend synchronizing (or time-stamping) imaging and visual stimuli during experiments. Depending on the scientific question and experimental design, the visual stimuli can be modified. Here we provide an example protocol for measuring the intensity-response function in fly ultraviolet (UV)-sensing photoreceptors using UV illumination. For this purpose, precise time-stamping or synchronization is not required.