SomArchon

Soma-targeted Archon1 variant designed for population voltage imaging.

Category: Opsin GEVI
Published: 2019-10-17 — Nature 2019
Derived from: Archon1
Response polarity: positive-going (fluorescence increases on depolarization)
Spectrum: excitation peak 586 nm, emission peak 693 nm (SomArchon)
Plasmid: Addgene #126941
Tags: Archaerhodopsin, Red

Headline values (as shown in the GEVIBench table)

Metric	Value	Definition
Brightness (B/B_EGFP)	0.01× 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)	0.60 / 1.1 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	+30%	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	0.35% (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	43% (median of 4 measurements: 40%)	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)	4.7 ms	Full width at half maximum of the optical spike waveform.
Photostability t75% @ 100 mW/mm²	49.0 min	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)	16	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 0.6 ms, τ_off 1.1 ms at 37°C — Lowet 2022, Main text

ΔF/F per 100 mV

+30%, 1P — Piatkevich 2019, Fig. 1g

ΔF/F per action potential

43%, 1P — Piatkevich 2019, Fig. 1d
37%, 1P — Piatkevich 2019, Fig. 1d
29%, 1P — Piatkevich 2019, Fig. 1d
53.4%, 1P — Piatkevich 2019, Ext. Fig. 5c

AP width (FWHM)

5.3 ms at 1000 Hz sampling, Mouse, cortex layer 2/3, acute brain slice; optical AP evoked by current injection, whole-cell patch clamp, 1P, 22°C — Piatkevich 2019, Fig. 1e
4.7 ms at 1000 Hz sampling, Mouse, hippocampus, acute brain slice; optical AP evoked by current injection, whole-cell patch clamp, 1P, 22°C — Piatkevich 2019, Fig. 1e
4.4 ms at 1000 Hz sampling, Mouse, striatum, acute brain slice; optical AP evoked by current injection, whole-cell patch clamp, 1P, 22°C — Piatkevich 2019, Fig. 1e

Brightness comparisons

28× the brightness of Arch — Monakhov 2020, Table 1
0.31545741324921134× the brightness of nirButterfly — Monakhov 2020, Fig. S2

Photobleaching

curve only (did not reach 75% within the measured window) at 44 mW/mm², 1P — Monakhov 2020, Fig. S2
t75% = 196 s at 1500 mW/mm² (637 nm), 1P — Piatkevich 2019, Ext. Fig. 5e

Fluorescence–voltage (F–V) curve

ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -100 mV: -9%; -80 mV: -3%; -70 mV: 0%; -60 mV: 4%; -40 mV: 11%; -20 mV: 17%; 0 mV: 22%; 20 mV: 26%; 40 mV: 30%; 60 mV: 32% — Piatkevich 2019, Fig. 1g

Research papers using SomArchon (16)

Population imaging of neural activity in awake behaving mice — Piatkevich KD, Bensussen S, Tseng HA, Shroff SN, Lopez-Huerta VG, Park D, Jung EE, Shemesh OA, Straub C, Gritton HJ, Romano MF, Costa E, Sabatini BL, Fu Z, Boyden ES, Han X, Nature 2019 (Mouse, cortex, hippocampus CA1, and striatum, in vivo awake head-fixed)
All-optical electrophysiology reveals the role of lateral inhibition in sensory processing in cortical layer 1 — Fan LZ, Kheifets S, Bohm UL, Wu H, Piatkevich KD, Xie ME, Parot V, Ha Y, Evans KE, Boyden ES, Takesian AE, Cohen AE, Cell 2020 (Mouse, barrel cortex layer 1 interneurons, in vivo awake)
Craniotomy Procedure for Visualizing Neuronal Activities in Hippocampus of Behaving Mice — Wang Y, Zhu D, Liu B, Piatkevich KD, Journal of Visualized Experiments 2021 (Mouse, hippocampus CA1, in vivo awake head-fixed)
Large-scale voltage imaging in behaving mice using targeted illumination — Xiao S, Lowet E, Gritton HJ, Fabris P, Wang Y, Sherman J, Mount R, Tseng HA, Man HY, Mertz J, Han X, iScience 2021 (Mouse, visual cortex and hippocampal CA1, in vivo awake; rat cortical neurons, in vitro)
Region-specific effects of ultrasound on individual neurons in the awake mammalian brain — Tseng HA, Mahoney CE, Bhatt DK, Xiao S, Bhatt RA, De La Croix Bhatt RS, Han X, iScience 2021 (Mouse, hippocampus and motor cortex, in vivo awake)
Visualizing Oscillations in Brain Slices With Genetically Encoded Voltage Indicators — Rhee JK, Iwamoto Y, Baker BJ, Frontiers in Neuroanatomy 2021 (Mouse, motor cortex brain slices, in vitro)
Deep brain stimulation creates informational lesion through membrane depolarization in mouse hippocampus — Lowet E, Kondabolu K, Zhou S, Mount RA, Ravasio C, Han X, Nature Communications 2022 (Mouse, hippocampal CA1, in vivo awake)
Membrane Voltage Dynamics of Parvalbumin Interneurons Orchestrate Hippocampal Theta Rhythmicity — Tseng HA, Bhatt DK, Bhatt RS, Han X, bioRxiv 2022 (Mouse, hippocampal CA1 parvalbumin interneurons and pyramidal cells, in vivo awake)
Theta and gamma rhythmic coding through two spike output modes in the hippocampus during spatial navigation — Lowet E, Sheehan DJ, Chialva U, De Oliveira Pena R, Mount RA, Xiao S, Zhou SL, Tseng HA, Gritton H, Shroff S, Kondabolu K, Cheung C, Wang Y, Piatkevich KD, Boyden ES, Mertz J, Hasselmo ME, Rotstein HG, Han X, Cell Reports 2023 (Mouse, hippocampal CA1, in vivo awake head-fixed)
Striatal cholinergic interneuron membrane voltage tracks locomotor rhythms in mice — Shroff SN, Lowet E, Sridhar S, Gritton HJ, Abumuaileq M, Tseng HA, Cheung C, Zhou SL, Kondabolu K, Han X, Nature Communications 2023 (Mouse, striatum cholinergic interneurons and spiny projection neurons, in vivo awake)
Photothrombosis induced cortical stroke produces electrographic epileptic biomarkers in mice — Shaw DC, Kondabolu K, Bhatt DK, Han X, bioRxiv 2024 (Mouse, motor cortex, in vivo awake)
Slow and fast cortical cholinergic arousal is reduced in a mouse model of focal seizures with impaired consciousness — Sieu LA, Bhatt DK, Bhatt RS, Han X, Cell Reports 2024 (Mouse, cortex, in vivo awake)
Large-scale deep tissue voltage imaging with targeted-illumination confocal microscopy — Xiao S, Cunningham WJ, Kondabolu K, Lowet E, Moya MV, Mount R, Ravasio C, Bortz E, Shaw D, Economo MN, Han X, Mertz J, Nature Methods 2024 (Mouse, visual cortex, motor cortex, and hippocampal CA1, in vivo awake)
Relative phase of membrane potential theta oscillations between individual hippocampal neurons code space — Athif M, et al., bioRxiv 2025 (Mouse, hippocampal CA1, in vivo awake head-fixed)
Imaging high-frequency voltage dynamics in multiple neuron classes of behaving mammals — Haziza S, et al., Cell 2025 (Mouse and rat, cortex, hippocampus, striatum, in vivo awake; fiber photometry with TEMPO)
Transcranial ultrasound stimulation modulates neuronal membrane potentials across broad timescales in the awake mammalian brain — Bortz E, et al., Brain Stimulation 2025 (Mouse, cortex, in vivo awake)

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.