Fig. 3

Recent rhodopsin-based GEVIs. a Representation of two kinds of rhodopsin-based GEVIs with PROPS type GEVI (left) and eFRET-based GEVI (right). b Left: Confocal images of QuasAr3 expression in brain slices; bar 50 μm. Middle: Patch-clamp recordings (black) with corresponding fluorescence traces (red) in acute brain slices. Right: overlay of electrical and optical signal for a single AP. Modified with permission from [55]. c Left: Expression of Archon1 in acute brain slices; bar 25 μm. Middle: Archon1 fluorescence (pink; single trial) and related electrical traces (black) in cultured cells with overlay of both signals for the AP indicated by the arrow. Right: Fluorescence changes (single trial) of Archon 1 following action potential-like voltage changes (black) of 200 Hz in a voltage-clamped neuron in culture. Modified with permission from [57]. d Left: Confocal image of VARNAM expression in pyramidal neurons in fixed postnatal brain slices. Middle: Concurrent optical (red) and electrical recordings (black) evoked by 10 Hz (left) and 50 Hz (right) current injections with overlay of both signals for indicated AP. Right: Changes in membrane potential driven by activation of the channelrhodopsin Cheriff (blue) monitored electrically (black) and optically (red). Modified with permission from [44]