Characterization and subcellular targeting of GCaMP-type genetically-encoded calcium indicators

Tianyi Mao, Daniel H. O'Connor, Volker Scheuss, Junichi Nakai, Karel Svoboda

Research output: Contribution to journalArticlepeer-review

136 Scopus citations


Genetically-encoded calcium indicators (GECIs) hold the promise of monitoring [Ca2+] in selected populations of neurons and in specific cellular compartments. Relating GECI flourescence to neuronal activity requires quantitative characterization. We have characterized a promising new genetically-encoded calcium indicator - GCaMP2 - in mammallian pyramidal neurons. Fluorescence changes in response to single action potentials (17±10% ΔF/F [mean ± SD]) could be detected in some, but not all, neurons. Trains of high-frequency action potentials yielded robust responses (302 ± 50% for trains of 40 action potentials at 83 Hz). Responses were similar in acute brain slices from in utero electroporated mice, indicating that long-term expression did not interfere with GCaMP2 function. Membrane-targeted versions of GCaMP2 did not yield larger signals than their non-targeted counterparts. We further targeted GCaMP2 to dendritic spines to monitor Ca2+ accumulations evoked by activation of synaptic NMDA receptors. We observed robust ΔF/F responses (range: 37%-264%) to single spine uncaging stimuli that were correlated with NMDA receptor currents measured through a somatic patch pipette. One major drawback of GCaMP2 was its low baseline flourescence. Our results show that GCaMP2 is improved from the previous versions of GCaMP and may be suited to detect bursts of high-frequency action potentials and synaptic currents in vivo. Copyright:

Original languageEnglish (US)
Article numbere1796
JournalPloS one
Issue number3
StatePublished - Mar 19 2008
Externally publishedYes

ASJC Scopus subject areas

  • General


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