a, Membrane properties of neurons expressing Archon (hashed boxes) or SomArchon (open boxes) in cortex layer 2/3 brain slices (P = 0.8026, 0.8895, and 0.8236 for resistance, capacitance, and resting potential, respectively; two-sided Wilcoxon rank-sum test comparing Archon1 versus SomArchon; n = 8 and 18 cells from 1 and 2 mice for Archon1 and SomArchon, respectively). b, Similar to a but in hippocampus (P = 0.6294, 0.9720, 0.8880, and 0.0037 for resistance, capacitance, resting potential, and FWHM, respectively; two-sided Wilcoxon rank-sum test comparing negative versus SomArchon; n = 8 and 7 cells from 2 mice each for negative and SomArchon for resistance and resting potential; n = 7 and 7 cells from 2 mice each for negative and SomArchon for capacitance; n = 7 and 8 cells from from 2 mice each for negative and SomArchon for FWHM). c, Similar to a but in striatum (P = 0.7380, 0.8357, 0.7751, and 0.0931 for resistance, capacitance, resting potential and FWHM, respectively; two-sided Wilcoxon rank-sum test comparing negative and SomArchon; n = 7 and 6 cells from 2 mice each for negative and SomArchon for resistance and capacitance; n = 6 and 7 cells from 2 mice each for negative and SomArchon for resting potential; n = 6 and 6 cells from 2 mice each for negative and SomArchon for FWHM). d, Changes in relative ROS concentration (normalized to that before illumination) over time in negative (solid line) and SomArchon-expressing (dashed line) cultured mouse neurons under various illumination protocols. e, Maximal increase in ROS concentration during continuous illumination for conditions performed in d (n = 45, 24, and 8 negative neurons from 2, 2, and 1 cultures for 390/22 nm, 475/36 nm, and 637 nm illumination, respectively; n = 24 SomArchon-expressing neurons for 637 nm illumination from 1 culture). f, Cell death for negative (solid line) and SomArchon-expressing (dashed line) cultured neurons at DIV 14–18 under various illumination protocols (n = 45, 35, 91, 40, and 27 neurons from 2, 1, 2, 1, and 1 cultures, respectively, for 390/22 nm at 2.8 mW mm−2, 390/22 nm at 5.5 mW mm−2, 475/36 nm at 12 mW mm−2, 475/36 nm at 25 mW mm−2, and 637 nm at 1,500 mW mm−2 illumination). g, Bright-field and fluorescence images of representative neurons expressing SomArchon before and after 10 min of continuous 637-nm laser illumination at 1,500 mW mm−2, followed by 10 min in darkness (93% of imaged cells did not exhibit noticeable changes in morphology; n = 27 cells from 1 culture; non-illuminated cells did not show any changes in morphology; n = 10 cells from 1 cultures). Scale bar, 50 μm. h, Representative SomArchon fluorescence trace from neuron co-expressing SomArchon and CoChR-K v 2.1 motif . i, Normalized spike rates (to initial value) elicited by blue light illumination dropped after 300 s of continuous recording, owing to decrease in spike amplitude as a result of photobleaching (n = 10 neurons from 1 culture; plotted as mean ± s.d.). j, Normalized (to initial value) FWHM of spikes elicited by continuous light exposure as in h. Box plots as in Fig. 1. Source Data