[Afferent projections to the nodulus in the cat. II. Mossy fiber projections].

Mossy fiber projections to the nodulus of the cerebellum were studied by retrograde axonal transport of horseradish peroxidase (HRP) in the cat. Following large and small injections into the nodulus, the distribution of labeled cells in the brainstem nuclei was investigated. Our observations provided evidence that the nodular afferents take their major origin from the medial, inferior and superior vestibular nuclei. On the other hand, minor sources projecting to the nodulus were from the x- and z-group. Of the perihypoglossal nuclei, it is only the prepositus hypoglossal nucleus which appears to be interconnected with the nodulus. There were no projections of the pontine nuclei and the nucleus reticularis tegmenti pontis to the nodulus. Injections of the nodular cortex revealed a distinct bilateral projection to this cortical area. The results showed no different projections between the dorsal and ventral nodulus. Mediolateral differences were not found in the nodulus.