Single-spike detection in vitro and in vivo with a genetic Ca2+ sensor.
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.
Wallace
Damian J
DJ
Max Planck Institute for Biological Cybernetics, Spemannstrasse 41, 72076 Tübingen, Germany.
Meyer zum Alten Borgloh
Stephan
S
Astori
Simone
S
Yang
Ying
Y
Bausen
Melanie
M
Kügler
Sebastian
S
Palmer
Amy E
AE
Tsien
Roger Y
RY
Sprengel
Rolf
R
Kerr
Jason N D
JN
Denk
Winfried
W
Hasan
Mazahir T
MT
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
D002147:Calmodulin; D011993:Recombinant Fusion Proteins; D002118:Calcium