In order to ascertain the presence of nerve fibers running directly from the cerebral cortex to the cerebellum, the authors performed their morphological researches on eleven rat brains. These rat brains, having received experimental destruction in the presumptive motor area of the cerebral cortex, were studied to trace the secondary degenerated nerve fibers by means of the Nauta and Marchi methods.
Fibers originating in the cerebral cortex were found to run to the cerebellum via the bilateral middle cerebellar peduncles and juxta-restiform bodies, but these fibers were few. Moreover, most of them were found to end in the ontogenetically newer cerebellar nuclei, such as the bilateral dentate nucleus, while only a remnat were followed to such medullary laminae of the neocerebellar cortex as the bilateral paramedian and ansiform lobules.
These findings showed that direct cerebro-cerebellar fibers were surely present and that their course was from the neocortex of the cerebrum to the neocerebellum, a conclusion which might serve to correct some of the defects in the information supplied by previous investigators.