Fast, in vivo voltage imaging using a red fluorescent indicator

Nat Methods. 2018 Dec;15(12):1108-1116. doi: 10.1038/s41592-018-0188-7. Epub 2018 Nov 12.

Abstract

Genetically encoded voltage indicators (GEVIs) are emerging optical tools for acquiring brain-wide cell-type-specific functional data at unparalleled temporal resolution. To broaden the application of GEVIs in high-speed multispectral imaging, we used a high-throughput strategy to develop voltage-activated red neuronal activity monitor (VARNAM), a fusion of the fast Acetabularia opsin and the bright red fluorophore mRuby3. Imageable under the modest illumination intensities required by bright green probes (<50 mW mm-2), VARNAM is readily usable in vivo. VARNAM can be combined with blue-shifted optical tools to enable cell-type-specific all-optical electrophysiology and dual-color spike imaging in acute brain slices and live Drosophila. With enhanced sensitivity to subthreshold voltages, VARNAM resolves postsynaptic potentials in slices and cortical and hippocampal rhythms in freely behaving mice. Together, VARNAM lends a new hue to the optical toolbox, opening the door to high-speed in vivo multispectral functional imaging.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Action Potentials*
  • Animals
  • Brain / cytology
  • Brain / physiology*
  • Cells, Cultured
  • Drosophila melanogaster / metabolism*
  • Electrophysiological Phenomena
  • Female
  • Fluorescent Dyes / chemistry*
  • HEK293 Cells
  • Humans
  • Image Processing, Computer-Assisted / methods*
  • Luminescent Proteins / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Microscopy, Fluorescence / methods*
  • Neurons / cytology
  • Neurons / physiology
  • Optogenetics

Substances

  • Fluorescent Dyes
  • Luminescent Proteins
  • red fluorescent protein