Extended Data Fig. 5: Photostability of paQuasAr3-s in vivo during ‘all-optical’ excitability measurements.

a, Fluorescence in the mouse hippocampus was recorded for 10-min in total. Oriens SST cells expressed paQuasAr3-s and CheRiff-s and were illuminated with red light at 12 W mm⁻² and stimulated with blue light (up to 10 mW mm⁻²) using the stimulation protocol presented at the top, during quiet and walking periods. The trace shows the fluorescence from two user-defined regions of interest after subtraction of the background from a cell-free region. The baseline signal photobleached in both cells by around 50% during this interval. Top, total acquisition. Dashed lines denote separate videos. Bottom, magnified views of the indicated regions from the top graph. Similar recordings were performed in five FOVs. b, The same two cells were imaged three weeks later. While at the end of the initial 10-min recording the SNR was low due to photobleaching, 3 weeks later the signal had recovered. Images show wide-field epifluorescence images of the cells in the two imaging sessions. Scale bars, 20 μm. c, Spike SNR was on average stable in repeated recordings over three weeks (P = 0.34, two-sided paired Student’s t-test).