Nat. Rev. Gastroenterol. Hepatol. doi:10.1038/nrgastro.2015.49 Figure 3 Schematic representation of the two main parallel pathways of excitatory and inhibitory neurotransmission of the enteric nervous system in the human LES Permission obtained from Lecea B, Thesis, Universitat Autònoma de Barcelona (2013) and John Wiley and Sons © Farre, D & Sifrim, D. Brit. J. Phharmacol. 153, 858–869 (2008)118 Clavé, P. & Shaker, R. (2015) Dysphagia: current reality and scope of the problem Nat. Rev. Gastroenterol. Hepatol. doi:10.1038/nrgastro.2015.49