The central cervical nucleus in the cat. III. The cerebellar connections studied with anterograde transport of 3H-leucine.

Injections of 3H-leucine were made into the region of the central cervical nucleus (CCN) in the C1--C4 segments of the spinal cord in 19 adult cats. In the cerebellum labelled mossy fibre terminals were found bilaterally concentrated in lobule I and adjoining parts of lobule II of the anterior lobe. In addition, a fair number of terminals were found in the basal parts of lobules III--VIII. The terminals were mainly found in the vermal zone. Only a minor proportion was observed in the intermediate zone of the anterior lobe and only occasionally were terminals seen in the hemispheral parts. No labelled climbing fibres were observed. Axons probably derived from the CCN were found to ascend in the brain stem, mostly contralateral to the injection site. They passed close to the vestibular nuclear complex and some fibres appeared to terminate in the nucleus x of Brodal and Pompeiano. The majority of axons entered the cerebellum via the superior cerebellar peduncle, a few via the restiform body. The findings suggest that lobules I--II are important recipients of information from the neck.