Fig. 2. Photoactivation of glutamatergic CnF neurons impacts respiratory rhythm generation in the preBötC.

a Transverse section showing the experimental strategy for photostimulating Glut⁺ CnF neurons in Vglut2^Cre adult mice. ChAT, Choline Acetyl Transferase. Scale bar, 1 mm. Representative of n = 7 mice. b Top: setup for recording ventilation using whole-body plethysmography (WBP) during CnF optogenetic activations. Middle: WBP recordings around a single 50 ms light pulse (vertical blue bar) of Glut⁺ CnF neurons during the expiratory phase of one respiratory cycle (inspirations are upwards, expirations are downwards). Note that the stimulation shortens the respiratory cycle. Bottom: magnification showing the control cycle (φ, black), the phase of light-simulation (φ_s, blue), and the perturbed cycle (θ, red). c Plot of the phase-shift (perturbed cycle normalized to control cycle: θ/φ) as a function of the phase of light-stimulation normalized to the control cycle (φ_s/φ). Values < 1 (purple line) indicate a shortening of the perturbed cycle. Inspiration (I) and expiration (E) mean durations are indicated. Note that the phase-shift is shortened when the light pulse occurs during expiration. Blue circles represent individual data from N random trials from n mice. White circles are averages ± SD across all trials within 0.1 ms bins. Source data are provided as a Source data file. d Left: experimental strategy for photostimulation of Glut⁺ CnF fibers in the ipsilateral preBötC in Vglut2 ^Cre adult mice. Right: transverse section at the level of the preBötC showing CnF eYFP⁺ projections and optic fiber placement in the preBötC. Scale bar, 200 µm. Representative of n = 4 mice. e, f Same as in b, c during a single 50 ms light-stimulation of CnF projections to the ipsilateral preBötC. Note that the respiratory cycle is shortened when light is delivered during expiration. N random trials from n mice. See also Figs. S3, S4, and S5. Source data are provided as a Source data file.