Single-spike detection in vitro and in vivo with a genetic Ca2+ sensor

Nat Methods. 2008 Sep;5(9):797-804. doi: 10.1038/nmeth.1242.


Measurement of population activity with single-action-potential, single-neuron resolution is pivotal for understanding information representation and processing in the brain and how the brain's responses are altered by experience. Genetically encoded indicators of neuronal activity allow long-term, cell type-specific expression. Fluorescent Ca2+ indicator proteins (FCIPs), a main class of reporters of neural activity, initially suffered, in particular, from an inability to report single action potentials in vivo. Although suboptimal Ca2+-binding dynamics and Ca2+-induced fluorescence changes in FCIPs are important factors, low levels of expression also seem to play a role. Here we report that delivering D3cpv, an improved fluorescent resonance energy transfer-based FCIP, using a recombinant adeno-associated virus results in expression sufficient to detect the Ca2+ transients that accompany single action potentials. In upper-layer cortical neurons, we were able to detect transients associated with single action potentials firing at rates of <1 Hz, with high reliability, from in vivo recordings in living mice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Animals
  • Brain / physiology*
  • Calcium / analysis*
  • Calmodulin / genetics*
  • Cells, Cultured
  • Dependovirus / genetics
  • Fluorescence Resonance Energy Transfer*
  • Hippocampus / physiology
  • Mice
  • Mice, Inbred C57BL
  • Recombinant Fusion Proteins / genetics*
  • Somatosensory Cortex / physiology
  • Synapses / physiology


  • Calmodulin
  • Recombinant Fusion Proteins
  • Calcium