Fig. 2: Optically induced tachycardia increases anxiety-like behaviour.
a, Schematic of a micro-LED mounted to a wearable vest and fastened onto a mouse. b, Representative ECG trace of optically induced tachycardia (900 bpm for 500 ms every 2 s) used for all behavioural assays. Scale bar, 0.2 mV, 500 ms. c, Example path trace of a mouse with (red) or without (grey) ChRmine expression during an RTPP test, in which mice received optically induced cardiac pacing on one side of the chamber. d, Percentage of time spent on stimulation side during baseline and stimulation days for control (grey) and ChRmine-expressing (red) mice (n = 16 mice per group; two-way repeated-measures ANOVA with Bonferroni post hoc test: group (opsin) × time interaction F(1,30) = 2.29, P = 0.14; group (opsin) effect F(1,30) = 6.2 × 10−4, P = 0.98; time effect F(1,30) = 2.06, P = 0.16. Bonferroni post hoc: control versus ChRmine P = 0.71 (baseline day); P = 0.67 (stimulation day)). NS, not significant. e, Average velocity on the optically paced side during RTPP (n = 16 mice per group; unpaired two-tailed t-test, P = 0.81). f, Example path trace of control (grey) and ChRmine-expressing (red) mice during an EPM test with optical pacing during the 5-min ON epoch of a 15-min trial. Open arms are vertical; closed arms are horizontal and bordered in grey. g, Time spent in open arms during 5-min epochs of EPM exploration (n = 16 mice per group; two-way repeated-measures ANOVA with Bonferroni post hoc test: group (opsin) × time interaction F(2,60) = 3.906, P = 0.0254; group (opsin) effect F(1,30) = 3.297, P = 0.0794; time effect F(2,60) = 9.75, P = 0.0002. Bonferroni post hoc: ON epoch ChRmine versus control, **P = 0.0079). h, Example path trace of control (grey) and ChRmine-expressing (red) mice during an OFT with optical pacing during the 3-min ON epoch of a 9-min trial. i, Time spent in the centre during 3-min epochs of OFT exploration (n = 5 (control), 9 (ChRmine) mice; two-way repeated-measures ANOVA with Bonferroni post hoc test: group (opsin) × time interaction F(2,24) = 1.531, P = 0.024; group (opsin) effect F(1,12) = 5.69, P = 0.0035; time effect F(2,24) = 3.42, P = 0.049. Bonferroni post hoc: ON epoch ChRmine versus control, *P = 0.018). j, Vogel conflict task to assay for cardiogenic effects on operant behaviour. Water-restricted mice were first trained for 2–3 weeks until each mouse was able to complete the 50 water-reward lever-press trials over 30 min for at least 3 consecutive days. On the day of the behavioural task, mice received optical pacing while completing a total of 50 lever-press trials per session (day 1). On the subsequent day, a 10% pseudorandom chance of shock was introduced upon lever press (day 2). k,l, Cumulative lever presses during 0% (day 1) and 10% shock (day 2) sessions for control (k) and ChRmine-expressing (l) mice (n = 8 mice). m, Average lever-pressing rate during 0% baseline or 10% shock trial sessions (n = 8 mice per group; two-way repeated-measures ANOVA with Bonferroni post hoc test: group (opsin) × condition (shock) interaction F(1,14) = 8.326, P = 0.0120; group (opsin) effect F(1,14) = 7.39, P = 0.0166; condition (shock) effect F(1,14) = 3.162, P = 0.0971. Bonferroni post hoc: control 0% versus 10%, P = 0.8933; ChRmine 0% versus 10%, *P = 0.0106; 0% control versus ChRmine, P > 0.9999; 10% control versus ChRmine, **P = 0.0010). n, Elapsed time between a lever press resulting in shock and a subsequent lever press as a measure of the mouse’s apprehension state. On 10% shock trials, 3 out of 8 mice did not complete the trial, so the time to next lever press for some trials cannot be measured (n = 40, 40, 40 and 32 presses per group in control 0%, control 10%, ChRmine 0% and ChRmine 10%; two-way ANOVA with Bonferroni post hoc test: group (opsin) × condition (shock) interaction F(1,148) = 6.478, P = 0.0119; group (opsin) effect F(1,148) = 5.041, P = 0.0262; condition (shock) effect F(1,148) = 7.253, P = 0.0079. Bonferroni post hoc: control 0% versus 10%, P > 0.9999; ChRmine 0% versus 10%, **P = 0.0026; 0% control versus ChRmine, P > 0.9999; 10% control versus ChRmine, **P = 0.0074). Data are mean ± s.e.m.
