PROJECTIONS FROM THE ROSTRAL PARVOCELLULAR RETICULAR-FORMATION TO PONTINE AND MEDULLARY NUCLEI IN THE RAT - INVOLVEMENT IN AUTONOMIC REGULATION AND OROFACIAL MOTOR CONTROL

The efferent connections of the rostral parvocellular reticular formation to pontine and medullary nuclei in the rat were studied with anterogradely transported Phaseolus vulgaris leucoagglutinin. Dense innervations from the rostral parvocellular reticular formation were found in the mesencephalic trigeminal nucleus, the supratrigeminal area, the motor trigeminal nucleus, the facial, hypoglossal and parabrachial nuclei and specific parts of the caudal parvocellular reticular formation, including nucleus linearis and the dorsal reticular nucleus of the medulla. The raphe nuclei, nucleus of the solitary tract, inferior olive, dorsal principal sensory, spinal trigeminal nuclei and gigantocellular reticular nucleus and the ventral reticular nucleus of the medulla received moderate projections. In general, the projections from the rostral parvocellular reticular formation were bilateral with an ipsilateral dominance. The dorsal motor vagus and the ambiguus nuclei were not labeled. It is concluded that the rostral parvocellular reticular formation participates in regulation of orofacial motor control and in neural networks for limbic control of metabolic homeostasis.