Figure 9. Schematic drawing representing present and previous findings on the connectivity within the respiratory network and relevant neurotransmitter influences.

The pTRG region is shown with its projections (pink) to ipsilateral and contralateral vagal motoneuron regions and to the contralateral pTRG (Gariépy et al. 2012; Cinelli et al. 2013). Excitatory (yellow) and inhibitory (blue) influences on the pTRG region (present findings and Mutolo et al. 2010, 2011; Cinelli et al. 2013) and the vagal motoneuron region (present findings) are illustrated. Newly identified excitatory projections to the pTRG (green) from neurons located in the vagal area have also been reported. ACh, acetylcholine; GABA, γ-aminobutyric acid; Gly, glycine; pTRG, paratrigeminal respiratory group region; SP, substance P; X, vagal motoneuron region.