Figure 2. Effects of continuous (10 s) and high frequency (20 Hz, 20 ms pulse) photostimulation of preBötC in urethane-anaesthetized SYN-ChR2-EYFP-treated rats.

A, long trace recording of ∫DIA_EMG, ∫GG_EMG, ∫ABD_EMG, respiratory rate (breaths min^–1, BPM) and laser activation shows that repeated photostimulation of preBötC induce reproducible and consistent increases in respiratory frequency in the presence of a continuous photostimulation (left, CP) and in presence of brief light pulses delivered at high frequency (HFP, 20 ms pulse at 20 Hz, right). Photostimulation events expanded in B are indicated with ‘i’ and ‘ii’ below the photostimulation protocol diagram. B, details of photostimulation protocols delivered in A. C, population data indicating changes in respiratory rate (RR), tidal volume (V_T), minute ventilation () and normalized changes in DIA_EMG and GG_EMG activity upon CP (circles) and HF photostimulation (squares). *Statistically significant changes (P<0.05) compared to pre-stimulation values.