Comparison of genetically encoded calcium indicators for monitoring action potentials in mammalian brain by two-photon excitation fluorescence microscopy

Borbala Podor, Yi Ling Hu, Masamichi Ohkura, Junichi Nakai, Roger Croll, Alan Fine

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

Imaging calcium transients associated with neuronal activity has yielded important insights into neural physiology. Genetically encoded calcium indicators (GECIs) offer conspicuous potential advantages for this purpose, including exquisite targeting. While the catalogue of available GECIs is steadily growing, many newly developed sensors that appear promising in vitro or in model cells appear to be less useful when expressed in mammalian neurons. We have, therefore, evaluated the performance of GECIs from two of the most promising families of sensors, G-CaMPs [Nat. Biotechnol. 19(2), 137-141 (2001)] and GECOs [Science 333(6051), 1888-1891 (2011)], for monitoring action potentials in rat brain. Specifically, we used two-photon excitation fluorescence microscopy to compare calcium transients detected by G-CaMP3; GCaMP6f; G-CaMP7; Green-GECO1.0, 1.1 and 1.2; Blue-GECO; Red-GECO; Rex-GECO0.9; Rex-GECO1; Carmine-GECO; Orange-GECO; and Yellow-GECO1s. After optimizing excitation wavelengths, we monitored fluorescence signals associated with increasing numbers of action potentials evoked by current injection in CA1 pyramidal neurons in rat organotypic hippocampal slices. Some GECIs, particularly Green-GECO1.2, GCaMP6f, and G-CaMP7, were able to detect single action potentials with high reliability. By virtue of greatest sensitivity and fast kinetics, G-CaMP7 may be the best currently available GECI for monitoring calcium transients in mammalian neurons.

Original languageEnglish
Article number021014
JournalNeurophotonics
Volume2
Issue number2
DOIs
Publication statusPublished - 2015 Apr 1
Externally publishedYes

Keywords

  • G-CaMP
  • GECO
  • calcium transients
  • genetically encoded calcium indicators
  • organotypic hippocampal slice
  • two-photon microscopy

ASJC Scopus subject areas

  • Neuroscience (miscellaneous)
  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging

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