Bioluminescent Multi-Characteristic Opsin for monitoring visual cortical activity upon optical stimulation

ABSTRACT Non-invasive detection of neural activity is important for the diagnosis of neurological diseases, evaluation of therapeutic outcomes, and collection of real-time feedback for stimulation based therapeutic approaches. In the case of vision loss, due to retinal degeneration, optic neuropathy, or enucleation of the eye, there is a need to map changes in visual cortical activity during disease progression and subsequent vision restoration by retinal, optic nerve or cortical stimulation. Existing technologies allow interrogation of neuronal circuits by both read and write activity, albeit with inherent limitations. Here, we present the development of bioluminescent multi-characteristic opsin (bMCO-11), which is comprised of a highly photosensitive ambient light-activatable domain and a Ca 2+ -sensitive bioluminescence reporter. The high quantum efficiency of bMCO-11 enables light activation and recording of cellular activity upon local as well as wide area optical stimulation. Furthermore, persistent Ca 2+ influx was achieved by bioluminescence based cyclic activation of the opsin-domain of bMCO-11 by transporting the ions only into bMCO expressing cells. This allowed us to continuously monitor visual cortical activity in wild type and retinal degenerated mice, without requiring any additional external excitation source.