| Autor: |
Brooks III, F. Phil, Davis, Hunter C., Wong-Campos, J. David, Cohen, Adam E. |
| Předmět: |
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| Zdroj: |
Neurophotonics; Jul2024, Vol. 11 Issue 3, p1-17, 17p |
| Abstrakt: |
Significance: Genetically encoded voltage indicators (GEVIs) are a valuable tool for studying neural circuits in vivo, but the relative merits and limitations of onephoton (1P) versus two-photon (2P) voltage imaging are not well characterized. Aim: We consider the optical and biophysical constraints particular to 1P and 2P voltage imaging and compare the imaging properties of commonly used GEVIs under 1P and 2P excitation. Approach: We measure the brightness and voltage sensitivity of voltage indicators from commonly used classes under 1P and 2P illumination. We also measure the decrease in fluorescence as a function of depth in the mouse brain. We develop a simple model of the number of measurable cells as a function of reporter properties, imaging parameters, and desired signal-to-noise ratio (SNR). We then discuss how the performance of voltage imaging would be affected by sensor improvements and by recently introduced advanced imaging modalities. Results: Compared with 1P excitation, 2P excitation requires ~104-fold more illumination power per cell to produce similar photon count rates. For voltage imaging with JEDI-2P in the mouse cortex with a target SNR of 10 (spike height to baseline shot noise), a measurement bandwidth of 1 kHz, a thermally limited laser power of 200 mW, and an imaging depth of >300 µm, 2P voltage imaging using an 80-MHz source can record from no more than ~12 neurons simultaneously. Conclusions: Due to the stringent photon-count requirements of voltage imaging and the modest voltage sensitivity of existing reporters, 2P voltage imaging in vivo faces a stringent tradeoff between shot noise and tissue photodamage. 2P imaging of hundreds of neurons with high SNR at a depth of >300 µm will require either major improvements in 2P GEVIs or qualitatively new approaches to imaging. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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