Figure 2 - Dorsal view of brainstem and cervical spinal cord indicating regions involved in control of breathing and progression of labeling with a viral tracer injected into the phrenic nerve.

KF, Kölliker-Fuse nucleus; PB, parabrachial nuclei; NA, noradrenergic A5 area; RTN, retrotrapezoid nucleus; PGi, paragigantocellular reticular nucleus; BötC, Bötzinger Complex; preBotC, preBötzinger Complex; rVRG, rostral ventral respiratory group; cVRG, caudal ventral respiratory group. (Source: Annual Review of Physiology, Volume 60, with permission. ©1998 by Annual Reviews. www.annualreviews.org.)