In principle, highly ¿uorescent rhodopsins could be employed as voltage sensors in neuroscience imaging. However,
rhodopsin mutants featuring a ¿uorescence ef¿ciency close to the one of the green ¿uorescence protein have not
been discovered yet. Most importantly, we lack the molecular-level understanding required to predict if and how a
speci¿c set of mutations can amplify the weak ¿uorescence of the rhodopsin chromophore. We propose to exploit
state-of-the-art quantum chemical methods to systematically investigate these issues and to reengineer a microbial
rhodopsin into a highly sensitive, genetically encodable, optogenetic tool for action potential visualization.