Genetically encoded voltage indicators (GEVIs) are emerging optical tools for acquiring brain-wide cell-type-specific functional data at unparalleled temporal resolution. To broaden the application of GEVIs in high-speed multispectral imaging, we used a high-throughput strategy to develop voltage-activated red neuronal activity monitor (VARNAM), a fusion of the fast Acetabularia opsin and the bright red fluorophore mRuby3. Imageable under the modest illumination intensities required by bright green probes (<50 mW mm⁻²), VARNAM is readily usable in vivo. VARNAM can be combined with blue-shifted optical tools to enable cell-type-specific all-optical electrophysiology and dual-color spike imaging in acute brain slices and live Drosophila. With enhanced sensitivity to subthreshold voltages, VARNAM resolves postsynaptic potentials in slices and cortical and hippocampal rhythms in freely behaving mice. Together, VARNAM lends a new hue to the optical toolbox, opening the door to high-speed in vivo multispectral functional imaging.

遗传编码的电压指示器（GEVI）是新兴的光学工具，可以无与伦比的时间分辨率获取全脑细胞类型的特定功能数据。拓宽GEVIs的高速多光谱成像中的应用，我们使用了高通量的策略开发电压激活红色神经元活动监视器（VARNAM），快速的融合伞藻属视蛋白和明亮的红色荧光团mRuby3。VARNAM可以在亮绿色探针（<50 mW mm ^-2）所需的适度光照强度下成像，很容易在体内使用。VARNAM可以与蓝移光学工具结合使用，以在急性脑切片和活果蝇中实现特定于细胞类型的全光学电生理学和双色尖峰成像。通过增强对亚阈值电压的敏感性，VARNAM解决了行为自由的小鼠的切片以及皮质和海马节律中的突触后电位。VARNAM共同为光学工具箱提供了新的色彩，为高速体内多光谱功能成像打开了大门。