Increased projection of ascending dorsal root fibers to vestibular nuclei after hemilabyrinthectomy in the frog.

The projections from brachial, ascending dorsal root fibers were studied autoradiographically in controls and chronically (four months) hemilabyrinthectomized frogs. Comparison showed that projections into the partially denervated vestibular nuclear complex of chronically hemilabyrinthectomized animals were far more dense than in control animals. In the cerebellar granular layer, no obvious difference in the extent of dorsal root projections was observed between both groups of animals. Cerebellar areas such as the auricular lobe and the dorsal rim, which normally receive many terminals from vestibular but not from dorsal root afferents, were not invaded by dorsal root fibers in chronically hemilabyrinthectomized frogs.