title: Single-spike detection in vitro and in vivo with a genetic Ca2+ sensor.
abstract: 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.
authors.affiliation: Max Planck Institute for Biological Cybernetics, Spemannstrasse 41, 72076 Tübingen, Germany.
authors.forename: Damian J
authors.initials: DJ
authors.lastname: Wallace
authors.forename: Stephan
authors.initials: S
authors.lastname: Meyer zum Alten Borgloh
authors.forename: Simone
authors.initials: S
authors.lastname: Astori
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.forename: Melanie
authors.initials: M
authors.lastname: Bausen
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kügler
authors.forename: Amy E
authors.initials: AE
authors.lastname: Palmer
authors.forename: Roger Y
authors.initials: RY
authors.lastname: Tsien
authors.forename: Rolf
authors.initials: R
authors.lastname: Sprengel
authors.forename: Jason N D
authors.initials: JN
authors.lastname: Kerr
authors.forename: Winfried
authors.initials: W
authors.lastname: Denk
authors.forename: Mazahir T
authors.initials: MT
authors.lastname: Hasan
mesh_terms: D000200:Action Potentials; D000818:Animals; D001921:Brain / Q000502:physiology*; D002118:Calcium / Q000032:analysis*; D002147:Calmodulin / Q000235:genetics*; D002478:Cells, Cultured; D000229:Dependovirus / Q000235:genetics; D031541:Fluorescence Resonance Energy Transfer; D006624:Hippocampus / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D011993:Recombinant Fusion Proteins / Q000235:genetics*; D013003:Somatosensory Cortex / Q000502:physiology; D013569:Synapses / Q000502:physiology
chemical_list: D002147:Calmodulin; D011993:Recombinant Fusion Proteins; D002118:Calcium