Fig. 1: Mapping dendritic voltages with all-optical electrophysiology.

a Top: genetic construct for co-expression of LR-Voltron2 and LR-CheRiff-eYFP. Bottom: optical system combining two-photon (2P) static structural imaging (dark red), micromirror-patterned dynamic voltage imaging (orange), and micromirror-patterned optogenetic stimulation (blue). DMD, digital micromirror device. Inset: micromirror-patterned red and blue illumination on a test slide. b Concurrent voltage imaging and whole-cell patch clamp recording at the soma. Sample rates: 1 kHz and 100 kHz, respectively. Spikes evoked by current injection (2 nA for 2 ms at 10 Hz). c Top: 2 P structural image of a CA1 neuron (gray), overlayed with eYFP epifluorescence indicating optogenetic stimulus region (blue; 10 ms duration to trigger a single bAP, 5 Hz). Bottom: optogenetic stimulation (blue) and voltage-dependent fluorescence at the soma (red). d Top: spike amplitude map from a spike-triggered average of 59 well-isolated spikes. Bottom: spike-triggered average voltage traces in the correspondingly numbered circled regions. ∆F_spike, peak spike amplitude. F_ref, mean amplitude during the reference time (from t = 10–20 ms after spike, Methods). e Spike delay map. f Sub-frame interpolation showing details of spike back-propagation (see also Supplementary Movie 3).