Cerebellar Projections of the Lagena (the Third Inner Ear Otolith Endorgan) in the Pigeon

We studied cerebellar projections of primary afferents coming from the lagena, the third inner ear otolith endorgan of the pigeon, using a technique of anterograde axonal transport of biotinylated dextran amine, BDA, applied to the region of the lagenar epithelium. Labelled fibers were found ipsilaterally in different lobules of the cerebellum, but mostly in caudoventral regions of the latter (lobules IX and X) and in lobule І. Among the cerebellar nuclei, labelled fibers were observed only in the lateral nucleus, and they passed along its lateral edge. Localization of the predominant part of primary lagenar afferents in the caudoventral cerebellar regions (which are classified as the vestibulocerebellum where primary and secondary vestibular fibers terminate) shows that the lagena in birds is functionally related to the vestibular system.