Extended Data Fig. 7: Effects of brain-noninvasive transcranial activation of 5-HT neurons on novelty preference, anxiety-related behaviors, and induction of the neural activity marker cFos.

a, Mice were assessed for novelty preference by quantifying ratio of time spent in the chamber containing a novel object relative to time spent in the empty chamber with and without photostimulation for YFP (gray) and ChRmine-eYFP (red) mice. Stimulation does not alter novel object interaction (n = 8 mice; two-sided paired t-test). b, Mice were assessed for anxiety-related behavior with a 15 min open field test, where the first and last 5 min block were not paired with light stimulation (OFF), while the middle 5 min was paired with 635 nm stimulation (800 mW mm^-2, 20 Hz, 5-ms pulse width repeated in 10 s intervals). Stimulation does not alter anxiety-behavior based on time spent in the center of the arena. (n = 8 mice; repeated-measure one-way ANOVA: F(2,14) = 2.23, P = 0.15 (eYFP) and F(2,14) = 0.05, P = 0.83 (ChRmine-eYFP)). c, Example path-tracing of a 5-HT ChRmine-YFP mouse during the 3 5-min blocks of the 15 min long open field test. Tracks are color coded for velocity (v). d, Representative confocal image of ChRmine-YFP neurons (white) in the raphe stained for cFos (magenta) by in situ hybridization and DAPI (blue). White arrows point to example YFP⁺/cFos⁺ neurons. Scale bar: 100 µm and (expanded view) 10 µm. e, Percentage of cFos⁺ cells among DAPI-labeled cells in the raphe following 10 min of transcranial photostimulation at 20 Hz and 800 mW mm^-2 with 5-ms pulse width. (n = 4 per group; one-way ANOVA: F(1,6)=16, P = 0.007). **P < 0.01; NS, not significant. Data are mean ± sem.