Lesion was made individually to the verious cortical areas in 14 adult cats.Thecorticofugal fibers terminating into vestibular nuclei were traced in sections by meansof modified Nauta silver staining method.The majority of cortical efferents which terminated to the vestibular nuclei deri-ved from somato-sensory area Ⅰ.A few fibers originated from the cortical motorareas,and some fibers derived from vestibular area and somatosensory area Ⅱ.Thefibers originated from the visual and auditory areas were not observed.The corticovestibular fibers descended within the pyramidal tract.These fibersleft pyramidal tract at the level of pons.Then,most of them reached to the vesti-bular nuclei ipsilaterally,and others reached bilaterally.Terminal degeneration was present throughout the whole extent of the vestibularnuclei.The total number of preterminal degenerating fibers in the nuclei was small.The anatomical and functional significance of our findings are discussed.

Lesion was made individually to the various cortical areas in 14 rats.The cortico- fugal fibers terminating into cochlear nuclei were traced in sections by means of the modified Nauta and Fink-Heimer silver staining method.The results were as follows: 1.After damaging the auditory area or somato-sensory area 1(SI)of the cerebral cortex unilaterally,degenerating fibers were found bilaterally in the ventral and dorsal cochlear nuclei.This result showed that the above cortical areas have direct descending connection with the cochlear nuclei. 2.No degenerating fibers were found in the cochlear nuclei after the ablation of the motor or visual area of the cerebral cortex,which demonstrated that the cochlear nuclei do not receive descending fibers from the above cortical areas. 3.The pathway from the cerebral cortex to the cochlear nuclei was:The descending fibers which originated from the auditory area or SI area ipsilaterally passed through the capsula interna and basis pedunculi,and part of these fibers passed dorsally and downward to the lateral portion of the reticular formation of the midbrain;and from there the fibers passed through the lemniscus lateralis and dorsal acustic stria to the cochlear nuclei of the ipsilateral side.The cochlear nuclei in contralateral side also received the corticofugal fibers by way of the dorsal acustic stria.These fibers might cross to the contralateral side at the region in the posterior commissure,superior colliculus commissure and inferior colliculus commissure.