Respiratory neurons in the region of the retrofacial nucleus: pontile, medullary, spinal and vagal projections.

Activities were recorded from single respiratory neurons in the area of the retrofacial nucleus. Stimuli were delivered in the dorsal (DRN) and ventral (VRN) medullary respiratory nuclei, the rostral pons, the cervical spinal cord and the vagus nerve to elicit antidromic potentials for these neurons and, hence, establish their axonal projections. The great majority of the antidromically activated retrofacial inspiratory neurons sent their axons to the contralateral VRN. A majority of expiratory neurons had their axons in the contralateral DRN or in both the DRN and spinal cord. For the phase-spanning neurons, the projections were found mainly in the VRN, spinal cord or pons.