GEVIBench › All sensors › ASAP6c
ASAP6c
Contrast-optimized descendant of ASAP4b with the largest per-spike fluorescence increase and signal-to-noise of the ASAP lineage for one- and two-photon spike detection in vivo.
- Category: VSD-cpGFP GEVI
- Published: 2026-05-04 — bioRxiv 2026
- Derived from: ASAP4b
- Response polarity: positive-going (fluorescence increases on depolarization)
- Spectrum: excitation peak 497 nm, emission peak 520 nm (ASAP6c)
- Two-photon compatible: yes
- Tags: cpGFP, Positive-going, Two-photon
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 0.11× EGFP | Molecular brightness relative to EGFP (extinction coefficient × quantum yield, or a measured ratio). Sensors not measured against EGFP directly are placed through a chain of pairwise brightness comparisons, combined by geometric mean. |
| Kinetics τ_on / τ_off (ms) | 3.9 / 4.4 ms | Activation / decay time constants in ms (amplitude-weighted mean τ for multi-exponential fits). The value shown averages the measurements made at physiological temperature (≥33 °C); if there are none, it is the measurement closest to 33 °C. |
| ΔF/F per 100 mV | +222% | Steady-state fluorescence change for a 100 mV depolarization step (−70 → +30 mV); the sign gives the polarity. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting. |
| ΔF/F per mV | 1.1% (estimated from the F–V curve) | Subthreshold sensitivity: fluorescence change per mV near rest (−90 to −50 mV). Where no value is reported directly, it is estimated from the F–V curve. |
| ΔF/F per AP | 70% (median of 3 measurements: 84%) | Fluorescence change per single action potential in neurons. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting. |
| AP width (FWHM, ms) | 5.3 ms | Full width at half maximum of the optical spike waveform. |
| Photostability t75% @ 100 mW/mm² | — | Time for fluorescence to fall to 75% of its initial value under one-photon illumination, linearly dose-scaled to 100 mW/mm² (t50% is used where the 75% crossing falls inside a fast initial transient). Two-photon curves are not dose-scaled and are excluded. |
| Papers using it (N_used) | 1 | Number of published research papers, tracked by GEVIBench, that used the sensor for an experiment (a popularity / track-record measure). |
Measurements and sources
Kinetics
- τ_on 3.93 ms, τ_off 4.41 ms at 25°C — Lee 2024, Table S3
ΔF/F per 100 mV
- +222%, 1P — Lee 2024, Table S2
ΔF/F per action potential
- 70%, 1P — Lee 2024, Table S2
- 98%, 1P — Lee 2024, Table S4
- 83%, 2P — Lee 2024, Fig. 3d
AP width (FWHM)
- 5.7 ms at 400 Hz sampling, Mouse barrel cortex L2/3 pyramidal neurons, in vivo, whisker stimulation (ASAP6c-Kv), 2P, 37°C — Lee 2024, Fig. 3d
- 4.9 ms at 800 Hz sampling, HEK293A cells, whole-cell voltage clamp, in vitro (simulated 2-ms-FWHM, 100-mV command AP waveform), 1P, 25°C — Lee 2024, Fig. 1d
Brightness comparisons
- 1× the brightness of ASAP4e — Lee 2024, Table S4
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -170 mV: -41%; -150 mV: -39%; -120 mV: -27%; -90 mV: -18%; -70 mV: 0%; -50 mV: 24%; -30 mV: 60%; -10 mV: 95%; 5 mV: 136%; 30 mV: 215%; 50 mV: 279%; 80 mV: 325% — Lee 2024, Fig. 1c
Research papers using ASAP6c (1)
- Improving positively tuned voltage indicators for faster kinetics and higher contrast — Lee S, Zhang G, Hao YA, Roth RH, Sun Y, Dong C, Zhu J, Gomez LC, Natan RG, Jiang D, Liu LX, Testa-Silva G, Hiramoto A, Roska B, Feldman D, Ji N, Clandinin TR, Giocomo L, Ding J, Lin MZ, bioRxiv 2026 (HEK293A cells, rat hippocampal neurons in vitro, mouse CA1 hippocampus in vivo (1P and 2P), mouse motor cortex in vivo (1P), mouse barrel cortex in vivo (2P), mouse visual cortex in vivo (FACED 2P), Htr3a+ interneurons in vivo)
Data and citation
- llms.txt — summary for language models
- llms-full.txt — every sensor in full (Markdown)
- gevis.json — all values and measurements with sources (JSON)
- gevis.csv — one row per sensor (CSV)
Cite GEVIBench as: Adam E. Cohen and Daozheng Gong (2026). Voltage imaging: A practical guide. Neuron. https://doi.org/10.1016/j.neuron.2026.08.002
Generated from the GEVIBench database on 2026-10-12.