Projections to Bötzinger expiratory neurons by dorsal and ventral respiratory group neurons.

Bötzinger complex (BOT) augmenting expiratory neuron efferent connection are well established, but little is known concerning the afferent neural projections to BOT. The dorsal (DRG) and ventral (VRG) respiratory groups were extensively searched in 17 pentobarbital anaesthetized cats for inspiratory neurons that were anti-dromically activated from BOT. Only 1 of the 60 VRG inspiratory neurons with confirmed spinal projection was antidromically activated from BOT. Another 3 VRG inspiratory neurons and 4 of the 30 DRG inspiratory neurons were activated from BOT, but none of these neurons had confirmed spinal cord projections. All 15 early burst neurons were antidromically activated from BOT. Neural projections to BOT from DRG and VRG inspiratory neurons are rare, but neural projections from early burst neurons are common.