Abstract :
Keywords Dorsal motor nucleus; Nucleus ambiguus; Nucleus tractus solitarii; Central connections; Polyvagal theory Highlights * Concise overview of vagal nuclei and their connections. * Concise overview of vagal targets focusing on cardio-pulmonary innervation. * Critical appraisal of the anatomical substrate of the polyvagal theory. Abstract Due to its pivotal role in autonomic networks and interoception, the vagus attracts continued interest from both basic scientists and therapists of various clinical disciplines. In particular, the widespread use of heart rate variability as an index of autonomic cardiac control and a proposed central role of the vagus in biopsychological concepts, e.g., the polyvagal theory, provide a good opportunity to recall basic features of vagal anatomy. In addition to the "classical" vagal brainstem nuclei, i.e., dorsal motor nucleus, nucleus ambiguus and nucleus tractus solitarii, the spinal trigeminal and paratrigeminal nuclei come into play as targets of vagal afferents. On the other hand, the nucleus of the solitary tract receives and integrates not only visceral but also somatic afferents. Abbreviations AMB, nucleus ambiguous; AMBc, nucleus ambiguus compact formation; AMBext, nucleus ambiguus external formation; AMBl, nucleus ambiguus loose formation; AMBsc, nucleus ambiguus semicompact formation; AMY, amygdala; CART, cocaine and amphetamine--regulated transcript; CCK, cholecystokinin; CGRP, calcitonin gene-related peptide; CVLM, caudal ventrolaterally medulla; DMX, dorsal motor nucleus of the vagus; GABA, gamma butyric acid; GLP, glucagon-like peptide; GLUT, glutamate; HRV, heart rate variability; IML, intermediolateral nucleus; MR, medullary reticular formation; NEBs, neuroepithelial bodies; NTS, nucleus tractus solitarii; PAG, periaqueductal gray; PBN, parabrachial nuclei; POMC, pro-opiomelanocortin; PTN, paratrigeminal nucleus; PrRP, prolactin-releasing peptide; PVT, polyvagal theory; RAR, rapidly adapting receptor; RSA, respiratory sinus arrhythmia; RVLM, rostral ventrolateral medulla; SAR, slowly adapting receptor; SMAR, smooth muscle associated receptor; SNpc, substantia nigra pars compacta; ST, solitary tract; vRESP, ventral respiratory group; X, vagus nerve; IX, glossopharyngeal nerve Author Affiliation: (a) Institute of Anatomy and Cell Biology, Friedrich-Alexander-Universität, Krankenhausstrasse 9, Erlangen, Germany (b) Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70808, USA * Correspondence to: Institute of Anatomy and Cell Biology, Friedrich-Alexander University Erlangen-Nürnberg, Krankenhausstrasse 9, 91054 Erlangen, Germany. Article History: Received 11 May 2022; Revised 7 September 2022; Accepted 7 September 2022 Byline: Winfried L. Neuhuber [winfried.neuhuber@fau.de] (a,*), Hans-Rudolf Berthoud [berthohr@pbrc.edu] (b)