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. Author manuscript; available in PMC: 2019 Jun 1.
Published in final edited form as: Curr Opin Neurobiol. 2018 Mar 20;50:146–153. doi: 10.1016/j.conb.2018.02.006

Figure 2.

Figure 2

Examples of genetically encoded voltage sensors (GEVIs) successfully used for recording neuronal activity in fruit fly (Drosophila melanogaster). Sophisticated genetic toolbox and tractability that allow for targeted expression made fruit fly a model of choice for functional testing of current generation of indicators. (a) Expression of GEVI ArcLight in fruit fly allows for recording of spontaneous electrical activity (subthreshold and action potentials) in intact neuronal circuits using single-photon excitation. Synchronous membrane activity was recorded in somata of multiple neurons (C1–3) and one neurite (N1) of wild-type clock neurons (ILNVs). Color coding of ROIs corresponds to the optical traces, The simultaneous whole-cell patch-clamp recording of the cell in the red ROI shown in black. Images were recorded at 500 Hz using 488 nm 50 mW laser with ~5 W/cm2 light power at the preparation. Scale bar is 10 μm, Taken from [38•], (b) Two-photon exciton was used in comparative study of several GEVIs expressed in L2 neurons in Drosophila visual system. Flies expressing VSD-based GEVIs (ASAP1, ASAP2s and ArcLight), opsin-based GEVIs (MacQ-mCitrine) and GECI GCaMP6f were tested with visual stimulus alternating between 300-ms dark (black bar) and light (white bar) flashes. Top: mean response across multiple cells (n = 44 cells/3 flies for ASAP1,111 cells/5 flies for ASAP2s, 65 cells/5 flies for ArcLight, 64 cells/3 flies for MacQ-mCitrine, 23 cells/4 flies for Ace2N-2AA-mNeon, and 232 cells/10 flies for GCaMP6f). For each cell recordings from 100 trials were averaged. Bottom: 5 examples of singe-trial responses from single L2 cell (in grey). Colored trace is mean response over 100 trials from the same cell. Cells were imaged at a frame rate of 38.9 Hz. Modified from [58••].