Organization of the core respiratory network: Insights from optogenetic and modeling studies
Fig 6
Perturbations of the inspiratory rhythm by bilateral photostimulation of VGAT-expressing inhibitory neurons within the Bötzinger complex in situ.
(A-D) Representative traces of phrenic nerve (PN) inspiratory activity show the response to short light pulses activating ChR2 in BötC inhibitory neurons. The upper traces show raw PN recordings, the middle traces show integrated phrenic activity (∫PN), and the bottom traces show the laser stimulus application with the laser intensity given below the stimulus. The timing of the laser stimulation is indicated with blue shading and dashed red lines. (A) Short (200 ms) low-intensity (1.0 mW) photostimulation pulse applied during the inspiratory phase terminated inspiration and elicited rebound excitation of inspiratory activity after the end of stimulation. (B) The same stimulation during the expiratory phase also caused rebound excitation of the next inspiratory phase after the end of the stimulus. (C and D) Long (5s) duration single photostimulation epochs inhibited the respiratory rhythm for the duration of light application and elicited rebound excitation of inspiratory activity similar to the short stimuli in panels A and B. (E) Population data (n = 5, mean ± SEM) shows that the latency between the end of the light stimulus and the onset of the next inspiration was independent of the stimulus duration. Short stim. = 200 ms; Long stim. = 5 s.