Figure 4.
Schematic drawing illustrating the two convergent pathways involved in the mediation of inspiratory off-switch (IOS) and inspiratory/expiratory (I/E) phase transition. (A) An afferent pathway mediating Breuer-Hering reflex originates from pulmonary stretch receptor input via the vagus and terminates in the nuclei of the solitary tract (NTS). (B) A central pathway that requires the Kölliker-Fuse nucleus (KF) of the pons involves reciprocal interaction between the KF and central pattern generator (CPG). Plasticity in the expression of the breathing pattern depends on intrinsic gating mechanisms (for details see text) of the CPG attributed to the KF and results from interaction between reciprocal connections of the afferent and the network pathways.