Bright and photostable chemigenetic indicators for extended in vivo voltage imaging

TLDR

Genetically encoded voltage indicators enable high‑resolution neuronal monitoring, yet their utility has been constrained by the limited brightness and photostability of fluorescent proteins and rhodopsins. The authors engineered Voltron, a GEVI that replaces protein fluorophores with bright, photostable synthetic dyes, boosting simultaneous neuron imaging by tenfold and extending imaging duration. Voltron was employed for in‑vivo voltage imaging in mice, zebrafish, and fruit flies. In mice, Voltron allowed single‑trial recording of spikes and subthreshold signals from dozens of neurons over 15 minutes, and in zebrafish it enabled precise correlation of spike timing with behavior.

Abstract

Genetically encoded voltage indicators (GEVIs) enable monitoring of neuronal activity at high spatial and temporal resolution. However, the utility of existing GEVIs has been limited by the brightness and photostability of fluorescent proteins and rhodopsins. We engineered a GEVI, called Voltron, that uses bright and photostable synthetic dyes instead of protein-based fluorophores, thereby extending the number of neurons imaged simultaneously in vivo by a factor of 10 and enabling imaging for significantly longer durations relative to existing GEVIs. We used Voltron for in vivo voltage imaging in mice, zebrafish, and fruit flies. In the mouse cortex, Voltron allowed single-trial recording of spikes and subthreshold voltage signals from dozens of neurons simultaneously over a 15-minute period of continuous imaging. In larval zebrafish, Voltron enabled the precise correlation of spike timing with behavior.