Fig. 1: Optogenetic activation of RtTg leads to stereotypical startle behaviour.

a Left: schematic for optogenetic activation of the RtTg. Right: a representative image confirming ChR2-EGFP expression in the RtTg, and the optical fiber trace. Scale bar, 400 μm. b Schematic for the optogenetic activation and the simultaneous whole-cell patch-clamp recording of RtTg EGFP⁺ neurons in the RtTg brain slice of mice receiving an intra-RtTg injection of the AAV-hSyn-ChR2-EGFP. c Sample traces showing the photostimulation (blue bars, 1 ms)-evoked action potentials in RtTg EGFP⁺ neurons. d Schematic for the optogenetic activation of the RtTg and simultaneous detection of startle reflexes. e Startle amplitude was defined as the largest peak-to-peak response occurred within 200 ms after the onset of the laser stimulus. f Startle amplitudes evoked by opto-stimulation (blue bars) of the RtTg neurons expressing ChR2 or EGFP (n = 15 mice per group, two-sided unpaired t-tests, P = 5.78 × 10⁻⁶). g Startle amplitudes at different laser intensities in the ChR2 and EGFP group (n = 15 mice per group). h Representative image showing the experimental setup for EMG recording during optogenetic activation of RtTg neurons. Blue arrows indicate positions for electrode insertion. i Example of the entire and locally amplified EMG traces showing activities of mouse hindlimb muscles during optogenetic activation (blue bar) of RtTg neurons. j Quantification of latency for hindlimb muscle EMG activities after optogenetic activation of the RtTg (n = 5 mice, 25 bouts in total). Error bar represent mean ± s.e.m. ***P < 0.001.