The avian nucleus retroambigualis: a nucleus for breathing, singing and calling.

Nucleus retroambigualis in songbirds and pigeon was found to contain expiratory-related neurons having spinal projections with terminations in close proximity to abdominal expiratory motoneurons. It was also shown to receive projections from the dorsomedial nucleus (DM) of the intercollicular complex and, in songbirds, from the nucleus robustus archistriatalis (nRbA) of the telencephalon. Nucleus retroambigualis is thus an important nexus in the final common pathway for respiration and vocalization.