Reciprocal connections between the red nucleus and the trigeminal nuclei: A retrograde and anterograde tracing study

An anterograde biocytin and a retrograde WGA-colloidal gold study in the ra t can provide information about reciprocal communication pathways between t he red nucleus and the trigeminal sensory complex. No terminals were found within the trigeminal motor nucleus, in contrast with the facial motor nucl eus. A dense terminal field was observed in the parvicellular reticular for mation ventrally to the trigeminal motor nucleus. The parvicellular area ma y be important for the control of jaw movements by rubrotrigeminal inputs. On the other hand, the contralateral rostral parvicellular part of the red nucleus receives terminals from the same zone in the rostral part of the tr igeminal sensory complex, where retrogradely labelled neurones were found a fter tracer injections into the red nucleus. Such relationships could be pa rt of a control loop for somatosensory information from the orofacial area.