(2014) Hochbaum, Daniel; Zhao, Yongxin; Farhi, Samouil; Klapoetke, Nathan; Werley, Christopher A.; Kapoor, Vikrant; Zou, Peng; Kralj, Joel M.; Maclaurin, Dougal; Smedemark-Margulies, Niklas; Saulnier, Jessica; Boulting, Gabriella; Straub, Christoph; Cho, Yong Ku; Melkonian, Michael; Wong, Gane Ka-Shu; Harrison, D. Jed; Murthy, Venkatesh; Sabatini, Bernardo; Boyden, Edward S.; Campbell, Robert E.; Cohen, Adam
All-optical electrophysiology—spatially resolved simultaneous optical perturbation and measurement of membrane voltage—would open new vistas in neuroscience research. We evolved two archaerhodopsin-based voltage indicators, QuasAr1 and 2, which show improved brightness and voltage sensitivity, microsecond response times, and produce no photocurrent. We engineered a novel channelrhodopsin actuator, CheRiff, which shows improved light sensitivity and kinetics, and spectral orthogonality to the QuasArs. A co-expression vector, Optopatch, enabled crosstalk-free genetically targeted all-optical electrophysiology. In cultured neurons, we combined Optopatch with patterned optical excitation to probe back-propagating action potentials in dendritic spines, synaptic transmission, sub-cellular microsecond-timescale details of action potential propagation, and simultaneous firing of many neurons in a network. Optopatch measurements revealed homeostatic tuning of intrinsic excitability in human stem cell-derived neurons. In brain slice, Optopatch induced and reported action potentials and subthreshold events, with high signal-to-noise ratios. The Optopatch platform enables high-throughput, spatially resolved electrophysiology without use of conventional electrodes.
