The ability to image brain activity is critical to understand how we learn, think, sense, plan movements, and behave. It can also help understand how neurological disorders impact brain function, paving the way for cures or treatments. A major challenge is that brain activity is rapid (millisecond-timescale) and operates at spatial scales down to less than 1/1000th of a millimeter. There are existing tools to image brain activity, but they have important limitations, such as being too slow to follow fast brain activity, having poor spatial resolution, being unable to record from many brain cells or only allowing imaging at the very surface of the brain. The investigators of this project are developing new sensors for imaging brain activity in animal models, thereby providing the research community with more powerful tools to study the brain in health and disease. The investigators engineer "voltage indicators," which are proteins who emit flashes of light when neurons are active. Previous studies demonstrated the potential for this technology, but developing better versions is laborious and time-intensive. Here, a new methodology for rapidly improving voltage indicators is being developed and disseminated to the broader community of neuroscientists and other biologists. The technology enables users to obtain improved versions on an accelerated timescale. The project also affords multi-disciplinary training opportunities for graduate students.
Monitoring voltage dynamics in defined neurons deep in the brain is critical for unraveling the function of neuronal circuits, but is challenging due to the limited performance of existing tools. The investigators address this technical need by developing Genetically Encoded Voltage Indicators (GEVIs), membrane-based fluorescent proteins whose brightness is modulated by transmembrane voltage. This emerging technology promises to fulfill the dream of recording electrical activity from many cells or subcellular locations in vivo and with cell type specificity. While GEVIs have enabled a restricted number of experiments in vivo, further improvement of their performance will be needed for broader use of these probes in vivo. In particular, GEVIs would benefit from increased sensitivity, brightness and photostability. To address the limitations of current indicators, the investigators are developing a microscopy platform that can rapidly screen indicator variants by automatically monitoring the variants' fluorescence responses to voltage changes. The investigators also are constructing several libraries of indicator variants, focusing on residues that are important for sensing the electrical field, or controlling fluorescence excitation or emission. The resulting indicators are characterized comprehensively across all key performance metrics to facilitate deployment in downstream applications. This NeuroNex Innovation Award is part of the BRAIN Initiative and NSF's Understanding the Brain activities.
