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Comparison of genetically encoded calcium indicators for monitoring action potentials in mammalian brain by two-photon excitation fluorescence microscopy
Author(s): Borbala Podor; Yi-ling Hu; Masamichi Ohkura; Junichi Nakai; Roger Croll; Alan Fine
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Paper 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 <italic<in vitro</italic< 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 [<mixed-citation publication-type="journal"< <source<Nat. Biotechnol.</source< <volume<19</volume<(<issue<2</issue<), <fpage<137</fpage<–<lpage<141</lpage< (<year<2001</year<)</mixed-citation<] and GECOs [<mixed-citation publication-type="journal"< <source<Science</source< <volume<333</volume<(<issue<6051</issue<), <fpage<1888</fpage<–<lpage<1891</lpage< (<year<2011</year<)</mixed-citation<], 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.

Paper Details

Date Published: 30 April 2015
PDF: 7 pages
2(2) 021014 doi: 10.1117/1.NPh.2.2.021014
Published in: Neurophotonics Volume 2, Issue 2
Show Author Affiliations
Borbala Podor, Dalhousie Univ. (Canada)
Yi-ling Hu, Dalhousie Univ. (Canada)
Masamichi Ohkura, Saitama Univ. (Japan)
Junichi Nakai, Saitama Univ. (Japan)
Roger Croll, Dalhousie Univ. (Canada)
Alan Fine, Dalhousie Univ. (Canada)

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