A photostable genetically encoded voltage indicator for imaging neural activities in tissue and live animals

Genetically encoded voltage indicators (GEVIs) enable noninvasive, high‑speed monitoring of electrical activity but are constrained by limited brightness and rapid photobleaching under continuous illumination. Here, we present Vega, a highly photostable green fluorescence GEVI with both high sensitivity (ΔF/F = -33% per 100 mV) and fast response (1.34 ms). Under one‑photon excitation at 1 W/cm2, Vega exhibits more than 20-fold slower photobleaching than the spectrally similar GEVI, Ace-mNeon2. In acute mouse brain slice, Vega enabled wide‑field high-fidelity recording of action potentials from 51 neurons simultaneously. In pancreatic islets, it revealed heterogeneous β-cell activation and intercellular coupling in response to glucose elevation. Finally, one‑photon imaging in awake mice demonstrated stable cortical voltage mapping in vivo. Vega thus overcomes the longstanding photostability-performance trade‑off, enabling chronic, high‑fidelity voltage imaging across preparations.