Figure 4. RL and RTN neurons are not essential for the expression or independence of cervical, lumbar, or VII respiratory motor outputs.
(A) E18.5 WT mice show respiratory co-activation of cervical (green), lumbar (magenta), and/or VII (dark blue) motor roots. Schematic (top) indicates maintenance of all RTN/pFRG and preBötC glutamatergic lineages. (B) Targeted loss of RL and RTN neurons in Atoh1LacZ/LacZ (RL−/RTN−) mice does not eliminate respiratory co-activation of cervical, lumbar, and/or VII respiratory outputs. Schematic (top) indicates targeted loss of Phox2b RTN (purple) and Atoh1 RL (orange) neurons. Arrows (A and B) indicate respiratory cervical outputs lacking lumbar or VII output. During single respiratory bursts, each motor pool can be co-active nearly simultaneously, with a temporal delay, or can be silent in relation to each other motor pool in WT (C and D) or in the absence of both RTN and RL neurons (E and F). (G) Stacked histograms showing the percentage of fictive breaths from each individual motor pool (cervical–C+, lumbar–L+, VII–VII+) where that motor pool fires either alone (bottom–black), fires with one of the two other motor roots (middle two bars, +cervical–green, +lumbar–magenta, +VII–dark blue), or where all three roots are co-active (top, C+L+VII–gray) from WT (left) or in Atoh1LacZ/LacZ (right) mice. Note the loss of RL and RTN neurons only affects the relative percentage of coupling. Scale bars = 10 s (A and B), 500 ms (C–F), 1 s (H). See Figure 4—figure supplements 1A–L for additional examples of the independence of respiratory motor pool co-activation in WT and Atoh1LacZ/LacZ mice. See Figure 4—figure supplements 2A–C for examples of independent lumbar activation and quantification of cervical and lumbar deletions in Phox2b-Cre;Atoh1LacZ/F (RL+/RTN−) mice.
Figure 4—figure supplement 1. Maintenance and independence of multiple respiratory motor outputs in RL−/RTN− mice.
Figure 4—figure supplement 2. Independent lumbar oscillator is transiently released in RL+/RTN− mice.
