FIGURE 3.

Schematic of the avian vocal control circuit highlighting the prominent position of the respiratory circuit (green) and its primary inputs from the “cortical” song system (blue) and viscerosensory afferents from the vocal respiratory apparatus (red)

For clarity, interconnectivity between the various divisions of the respiratory group is not shown. Anatomical names for each structure are placed to the left in bold, with likely mammalian homologs indicated in italics. RA, robust nucleus of the arcopallium; Uva, nucleus uvaeformis; DM, dorsomedial nucleus of the intercollicular complex; PBvl, ventrolateral part of the parabrachial nucleus; IOS, nucleus infra-olivarus superior; RVL, ventrolateral nucleus of the rostral medulla; PAm, nucleus parambigualis; nTS, nucleus of the solitary tract; RAm, nucleus retroambigualis; XIIts, tracheosyringeal part of the hypoglossal nucleus; Insp, inspiratory motoneurons at the level of spinal cord segment 14 (lower brachial); Exp, expiratory motoneurons at the level of spinal cord segment 19 (lower thoracic); PAG, periacqueductal gray; PRG, pontine respiratory group; pFRG, para-facial respiratory group; BötC, Bötzinger complex; preBötC, pre-Bötzinger complex; rVRG, rostral ventral respiratory group; cVRG, caudal ventral respiratory group.