July 10, 2014

Do your thoughts and feelings have colors? Do you feel red with rage during traffic, or green with envy when your lady swoons over Ryan Gosling? A recent methods paper introduces a very cool technique that allows the visualization and measurement of voltage within an excited neuron.

Biologists build tools that are ideally accurate, fast, and non-damaging to the cells and organisms on which they are used. In a recent paper in Nature Methods, Hochbaum and colleagues describe the improved technique for simultaneous imaging of neuron stimulation and the resulting action potentials. Hochbaum and colleagues engineered a vector, called Optopatch, that uses their actuator (CheRiff) to induce action potentials and their voltage indicators (QuasAr1 and QuasAr2) to visualize and measure membrane voltage. Optopatch allows the measurement of action potentials on a microsecond timescale, without the need for electrodes. In the images above, a neuron expressing Optopatch shows action potential propagation (left to right, arrow is site of action potential initiation).

Hochbaum, D., Zhao, Y., Farhi, S., Klapoetke, N., Werley, C., Kapoor, V., Zou, P., Kralj, J., Maclaurin, D., Smedemark-Margulies, N., Saulnier, J., Boulting, G., Straub, C., Cho, Y., Melkonian, M., Wong, G., Harrison, D., Murthy, V., Sabatini, B., Boyden, E., Campbell, R., & Cohen, A. (2014). All-optical electrophysiology in mammalian neurons using engineered microbial rhodopsins Nature Methods DOI: 10.1038/nmeth.3000
Adapted by permission from Macmillan Publishers Ltd, copyright ©2014